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SCANNER surveys for Local Roads User Guide and Specification

1. Note 2 An invalid speed value must be output as 9999 Transverse profile data Record S5 1 Repeated as necessary to provide number of values as defined by length of survey number of transverse profile points and spacing of profiles Characters Description Format Value range 1 80 Up to 16 profile point values 1615 9999 to measured in 1 10mm see Note 9999 1 below Table 7 13 Record S5 1 Repeated as necessary to provide number of values as defined by length of survey number of transverse profile points and spacing of profiles Note 1 An invalid transverse profile value must be output as 99999 99 SCANNER User Guide and Specification Volume 5 Wheel path rutting data 7 4 17 Record S6 1 Repeated as necessary to provide number of values as defined by length of survey and spacing of values 10 pairs of rut depths per record Characters Description Format Value range 1 4 Rut depth in nearside 14 0 to 9998 wheelpath measured in 1 10mm See Note 1 below 5 8 Rut depth in offside wheelpath 14 0 to 9998 measured in 1 10mm See Note 1 below 9 16 As Cols 1 8 for next pair of rut depths 17 24 As Cols 1 8 for next pair of rut depths 25 32 As Cols 1 8 for next pair of rut depths 33 40 As Cols 1 8 for next pair of rut depths 41 48 As Cols 1 8 for next pair of rut depths 49 56 As Cols 1 8 for next pair of
2. Cval n l where any invalid profile is excluded from the summation and Teva is the number of summed valid profiles The reported value DeVrpnsvave is the average of DevVrpns for valid profiles within the reporting length Te 1 DeV ppnscavey Devons n Tova n l where any invalid profile is excluded from the summation and Teva is the number of summed valid profiles The reported value Devfpos ave is the average of DeVrpos_ for valid profiles within the reporting length Te aa gt Dev pos T Cval n l D EV repos ave T where any invalid profile is excluded from the summation and Teva is the number of summed valid profiles Cleaned Rut Depths The overall process can be summarised as Calculate the rut depth in the nearside of the slope and offset suppressed cleaned transverse profile Calculate the rut depth in the offside of the slope and offset suppressed cleaned transverse profile 3 6 2 3 6 3 3 6 4 3 6 5 Section 3 Transverse Profile Parameters The outputs from the algorithm are The average value of the nearside rut depth in the cleaned transverse profiles Rutnsc ave in the reporting length The average value of the offside rut depth in the cleaned transverse profiles Rutosc ave in the reporting length For definitions relating to this algorithm see section 3 3 The algorithm should be applied to each cleaned profile with the slope and off
3. Cleaned transverse profile Figure 3 3 Flow chart for the cleaning algorithm Normalising 3 4 6 For each valid transverse profile within the survey the lowest profile height is found This value is then subtracted from all of the profile heights y within that profile Y Y Min y9 1 1 0 q9 1 26 3 4 7 3 4 8 3 4 9 3 4 10 Section 3 Transverse Profile Parameters Note from this point onwards within section 3 4 reference to y individual recorded transverse profile data refers to profile data that has been normalised as specified in paragraph 3 4 5 Smoothing Smoothing of the transverse profile is carried out when the transverse spacing of the measured points in the transverse profile is less than t Note smoothing is only likely to be required for a scanned profile and not for a profile generated from a number of individual lasers Smoothing the transverse profile is intended to remove noise from the transverse profiles To smooth the transverse profile a moving average filter of length 2t is used This method uses a moving average window to model a data point as the average of qui points on the left of the data point and qri points on the right of each data point as 1 i 9Ri DY DSe o 1 41 qpri j i q1 where qL and gr should be calculated for the i transverse position as follows qu maxA for which x _ 20 and x gt x t Gr ma
4. zj is the height of the filtered longitudinal profile point j in mm The principles described in paragraphs 2 3 7 through 2 3 9 also apply when calculating Enhanced Variance i e The extra readings as defined in paragraph 2 3 7 are used in calculating the filtered longitudinal profile heights however a filtered longitudinal profile height need not be calculated for those points and is not included in the calculation of Enhanced Variance When a reading falls exactly on the boundary between two reporting lengths it is deemed to lie within the former of those lengths 15 SCANNER User Guide and Specification Volume 5 At the start and end of the survey there will be lengths over which it is not possible to calculate filtered longitudinal profile heights Reporting lengths that include these is considered invalid and therefore not reported in the HMDIF file 2 5 The Bump Measure 2 5 1 The calculation of the Bump Measure can be summarised as follows The Central Difference Method is applied twice to the longitudinal profile to produce two separate datasets Thresholds are applied to these datasets to obtain a value for the Bump Measure over the reporting length The Central Difference Method 2 5 2 Given a set of data points dj zi where zj is the raw profile height in millimetres measured at distance dj in metres then the value obtained when the Central Difference Method at point j is d
5. Reporting Length Number of Profiles 0 10 100 10 20 101 20 30 101 30 40 101 40 50 100 Etc Table 3 2 Reporting length versus number of readings In such situations the extra profiles at the end of the reporting lengths are not be used in any of the calculations When a transverse profile falls exactly on the boundary between two reporting lengths it is deemed to lie within the former of those lengths e g With a reporting length L of 10m and an spacing D of exactly 0 1m the 100th profile at chainage 10m is deemed to lie within the 0 10m reporting length Cleaning the transverse profiles identifying the road edge The overall process can be summarised as shown in Figure 3 2 The output from the algorithm is The location of the edge of the road as found in the re sampled transverse profile n reported as en the distance from the first sensor position nearside The cleaned transverse profile the re sampled profile with profile heights to the left of position en reset to zero For definitions relating to this algorithm see section 3 3 23 SCANNER User Guide and Specification Volume 5 3 4 4 24 Normalise smooth if appropriate and re sample the transverse profile data Se Calculate the best transverse profile defining the representative shape of the re sampled transverse profiles within an averaging length with points to the le
6. The output value is R Edge roughness value proportion taking a value between 0 and 1 inclusive Figure 3 13 may aid in visualising the edge roughness measure The requirement is that an approximately 0 6m moving average longitudinal profile variance MALPV is calculated for those points which are within the edge strip extending within each transverse profile from en as defined in paragraph 3 4 36 to e 500mm MALPV values are calculated for points which lie exactly at en or en 500mm within their transverse profile MALPV values are not calculated for transverse profiles lying within the first approximately 0 3m or last approximately 0 3m of the reporting length as there are insufficient points to do so MALPV values are also not calculated where to do so would involve an invalid transverse profile Edge roughness R is calculated as the proportion of MALPV values calculated within the reporting length that exceed VLim Section 3 Transverse Profile Parameters eee S re eon try ria a ieee eee ff ape Ta a iN j a ba CPN bt ke tA ye ts See eee Lot oi AiG i ha 3 0 0m ker WAT ri PR EuS i toga vel 7 itt A Lenet t g 1 _ E a 7 1A 1 5 4 fe oer REE i Ceem rr Seuss i x w 1 1 lai 3 is ey WOGHEEE l N 1 ta li n IYE oe eee a i to rg ig l w Transverse profiles spaced at approx 0 1m longitudinally Paths traversed by points in the Transverse Profi
7. Transverse Profile Parameters For the purposes of analysis points that fall exactly on the boundary between Q and Q are deemed to lie within Q Points that fall exactly on the boundary between Q and Q are deemed to lie within Q4 Sensor measurements within Q2 and Q3 are always considered together Unwanted points may be caused by measurements overlapping a kerb or footway as shown in Figure 3 9 where d is a pre defined height typically 20mm LA d gt pre defined height D Q Q2 Figure 3 9 Eliminating unwanted points In the situation shown in Figure 3 9 points D4 and D2 should be eliminated i e excluded from the calculation of the nearside cleaned rut depth In the general case when calculating the nearside cleaned rut depth All points from D to Din 1 should be eliminated where D n1 Dn gt d and Dn is within Q4 Similarly when calculating the offside cleaned rut depth All points from Dins1 to Dz should be eliminated where D n 1 Dn gt d and Dn is within Q4 Identification of an inadequately measured profile An inadequately measured profile may be caused by there being insufficient points outside the wheel path as shown in Figure 3 10 where s is a pre defined slope typically 15 In the situation shown in Figure 3 10 the profile should be considered as inadequate and the nearside cleaned rut depth should not be calculated 43 SCANNER User Guid
8. Tave y n n l F aveval y where y n is the nth individual re sampled transverse profile within the averaging length Any invalid profile is excluded from the summation and Tavevai is the number of Summed valid profiles The average profile obtained best represents the shape of the road within the averaging length Locating the road edge in the average profile The first derivatives of the average profile are calculated as Ay Ax and the second derivatives are calculated as A y Ax as follows Ay y Yi y gt pe i 1 N 1 y Ax Yi F7 aa V D y Dey eee i 2 N 1 t y 0 y Oand y 0 The first and second derivatives are used to locate the road edge The sign of the second derivative at the location where the first derivative tends to zero is used to determine the nature of the kerb feature whether it is the top or bottom of a feature Depending on the type of curvature the algorithm searches for a minimum or a maximum The minimum will indicate the top of a kerb or rut and the maximum will indicate the bottom of a kerb or rut The algorithm distinguishes between the descending step of a kerb and of a rut by calculating the ratio between the maximum second derivative in the left third of the profile according to the procedures below and the 29 SCANNER User Guide and Specification Volume 5 3 4 21 3 4 22 3 4 23 30 maximum second derivative in the r
9. Delivered in the RCD file Raw texture profile for the nearside wheel track Multiple Line Root Mean Square Texture Depth RMST Delivered in the HMDIF file Nearside Sensor Measured Texture Depth SMTD Nearside Mean Profile Depth MPD Mean RMST i Nearside ii Middle iii Offside Variance in RMST i Nearside ii Middle iii Offside Texture Variability i 5th Percentile RMST ii 95th Percentile RMST iii Variance in RMST These parameters are calculated before any fitting is carried out on the Survey Data e g fitting to the Employer s network Before the parameters are calculated checks must be carried out on the validity of the data as described in Section 5 2 Checking the texture data Any individual texture parameter calculated from the raw texture profile e g SMTD RMST is considered invalid if more than a defined percentage typically 5 of the texture profile points used to calculate the texture profile parameter within the calculation length is invalid Any mean percentile or variance parameter calculated over a reporting length for that parameter e g 10m mean SMTD or 10m mean RMST is considered invalid and therefore not reported in the HMDIF file if more than a defined percentage typically 50 of the individual parameters 5 3 5 3 1 5 3 2 5 3 3 5 3 4 Section 5 Texture Profile Parameters within the reporting length e g of the 33 SMTDs within a 10m le
10. n 1 n 1 Nee as eae me iy ranging from 2 at point 1 to 2 at point n yi sensor measurement at point i The SMTD value averaged over the reporting length L is given by 1 df SMTD SMTD t Spal 2 5 where SMTDp values are calculated for successive standard deviation lengths within the reporting length any invalid SMTDp value is excluded from the summation and Jval is the number of valid SMTDp values summed e g With Texture Profile points at exactly 0 001m interval a standard deviation length of 0 3m and a reporting length of 10m if the Texture Profile point at the start of the length L was numbered 1 the first SMTDp would be calculated using points 1 through 301 the second using points 302 through 602 and the last 33rd using points 9633 through 9933 The last 67 points 9934 through 10000 within the reporting length would not be used The method for calculating SMTD must include the following configurable parameters The standard deviation length default 0 3m The reporting length default 10m Nearside Mean Profile Depth MPD Nearside Mean Profile Depth is calculated from the texture profile recorded in the nearside wheel track as described in the following paragraphs The evaluation of Mean Profile Depth MPD is generally as defined in ISO 13473 1 1997 E Characterization of pavement texture by use of surface profiles Part 1 Determination of Mean
11. described in more detail in sections 3 4 29 to 3 4 32 The highest correlation value R corresponds to an optimum shift dmax Figure 3 4 illustrates the principle behind the cleaning algorithm based on the cross correlation of the best profile with an individual transverse profile The calculation is iterative The correlation value R is calculated for each shift of the best profile with respect to the raw profile A maximum correlation corresponds to an optimum shift dmax for which the optimum alignment of the best profile and the individual transverse profile is obtained Section 3 Transverse Profile Parameters Aligning of transverse profiles Best profile ee ii eH leo TP to clean Shifting transverse profiles d max le 3 4 35 3 4 36 d max Figure 3 4 Principle of the cleaning algorithm The process required to calculate dmax is described in the following paragraphs The discrete correlation of two real pairs is defined as Sbon 5G ad u r d corr i i d Wie with SF Ms aif N d 35 SCANNER User Guide and Specification Volume 5 3 4 37 3 4 38 3 4 39 3 4 40 3 4 41 3 4 42 36 i N 1 2O i d H Na i N d 1 2 2 _i 0 fee N d i N 1 5O u 2 i d o N d where y i is the indicial form of the re sampled transverse profile y i is the indicial form of the best transverse profile i is the inde
12. header data The Contractor provides the following header data for a survey e Machine identifier Date at the start of the survey Time at the start of the survey Date at the end of the survey Time at the end of the survey Survey identifier descriptive text Co ordinates x y and z at the start of the survey data e Status for co ordinates at the start of the survey 89 SCANNER User Guide and Specification Volume 5 7 3 2 7 3 3 90 Chainage at the end of the survey data Co ordinates x y and z at the end of the survey data Status for co ordinates at the start of the survey Number of nodes identified and recorded Chainage interval between geometric measurements Chainage interval between nearside and offside longitudinal profile points and associated speed Offset of longitudinal profile measurement relative to the centre of the vehicle Chainage interval between transverse profiles Number of points within each transverse profile Offset of each transverse profile point relative to the centre of the vehicle Chainage interval between wheel path rutting values Chainage interval between texture profile points Offset of texture profile measurement relative to the centre of the vehicle Chainage interval between multiple line RMST values Number of points within each multiple line texture measurement Number of crack
13. in each wheelpath iv The rut depths and cleaned rut depths in each wheelpath v The transverse unevenness vi The edge roughness vii The Nearside SMTD viii The Nearside Middle and Offside Mean RMST ix The Texture Variability Reported as a percentage over 50m lengths i The cracking intensity The Accreditation Tester also produces a forward facing video record of the test route surveyed by HARRIS for reference purposes The Accreditation Tester provides the Contractor with a map showing the location of the test sites the description of each Section start and end point and the Section Labels The Accreditation Tester provides the Contractor with OSGR co ordinates of some but not all of the Section start points The Contractor Defines survey routes appropriate for the surveys of these sites and delivers the planned route to the Accreditation Tester as required for Network surveys in accordance with the requirements of the SCANNER survey specification for survey routes 8 13 8 8 13 9 8 13 10 Section 8 Accreditation Testing Carries out at least one survey of each route or more if required by the Accreditation Tester Wherever possible the Contractor takes measurements in the left most traffic lane except where otherwise instructed by the Accreditation Tester Uses an appropriate method to record the location of the Section start points for which OSGR co ordinates are provided and applie
14. m 2 1 m 2 Note Only m 1 values are applied for the coefficients of the band pass filter to increase efficiency with negligible loss of accuracy Note The convolution procedure can be visualised as the high pass and low pass coefficients being progressively overlapped At each overlap position the value of the convoluted coefficient is equal to the product of the corresponding high pass and low pass coefficients summed over the overlap region The convolution is applied to obtain m 1 values of bpi It is assumed that extending the convolution to obtain 2m 1 values 69 SCANNER User Guide and Specification Volume 5 5 5 10 5 5 11 5 5 12 70 would not significantly increase the performance of the filter for this application The value of the filtered longitudinal profile height z at each position i is obtained by multiplying the profile heights between Z i m2 and Z i m 2 by the corresponding m 1 band pass filter coefficients and then summing the resulting products m 2 ts Hence Zi DN bp j m 2 It can be inferred from the above definition that the calculation of the filtered profile cannot be performed within a distance of m 2 points of the start of the survey or m 2 points of the end of the survey Points falling in these lengths are defined as invalid for the purposes of calculating the texture parameters obtained from the filtered texture profile Individual Roo
15. nearside and offside in a reporting length Te L D rounded down to the nearest integer 57 SCANNER User Guide and Specification Volume 5 n index for the measured rut depth pair within the reporting length Rut individual measured nearside left wheel path rut depth Rute individual offside right wheel path nearside rut depth 4 4 Average Rut Depths 4 4 1 Where the reporting length is not an exact multiple of longitudinal spacing between successive measured rut depths there will be more measured rut depths than required within some reporting lengths e g With a reporting length of 10m and a longitudinal spacing between successive measured rut depths of 0 09925m Te will be calculated as 10 0 09925 100 75567 rounded down to 100 However the number of measured rut depth pairs lying within each 10m reporting length will be as shown in Table 4 1 In such situations the extra measured rut depths at the end of the reporting lengths are not used in calculating the averages Reporting Length Number of Readings 0 10 100 10 20 101 20 30 101 30 40 101 40 50 100 Etc Table 4 1 Reporting lengths versus number of readings When a pair of measured rut depths falls exactly on the boundary between two reporting lengths it is deemed to lie within the former of those lengths 4 4 2 e g With a reporting length of 10m and a
16. rounded to 50 i e the 5th percentile will be the 50th lowest of the 996 values Similarly the 95th percentile will result in a value of i 996 95 100 946 2 rounded to 946 i e the 95th percentile will be the 946th lowest of the 996 values Variance The variance is defined as 1 N Variance aay gt RMST RMST where j l 73 SCANNER User Guide and Specification Volume 5 74 RMST is the mean RMST value calculated by averaging the valid individual RMST values from all texture measurement lines over the texture variability reporting length using the approach described for the mean nearside RMST paragraph 5 5 12 N is the number of valid individual RMST values from all measurement lines in the texture variability reporting length L RMST is the jth valid individual RMST value from all measurement lines in the texture variability reporting length L Invalid individual RMST values are not included in the summation and Nval is the number of valid Summed individual RMST values Typical Values Checks and Limits Typical values to be confirmed during acceptance tests for the checks and limits to be placed on the texture profile parameters are given in Table 5 2 Parameter Typical Value SMTD standard deviation length m 0 3 MPD moving average length m 0 005 MPD baseline length m 0 1 Individual RMST calculation length m 0 1 M
17. x x as in paragraph 3 4 10 Then the re sampled profile is calculated as y a x b X x e Na x d where j is an index representing the points in the re sampled profile with j 0 1 2 3 N 1 where the appropriate value for depends upon each re sampling position Xj for each position i should be taken as the largest i for which Xi lt xj Solving algebraic equations with a tri diagonal matrix A system of equations with a tri diagonal matrix is written as d x x b a x d x c x b a x d x C x b a jX d x c x b a x d x b Set d d and b b Calculate m a d d ia d a m c _ 1 b i 1 Bis m b i where i 1 2 3 n 1 3 4 15 3 4 16 3 4 17 3 4 18 3 4 19 3 4 20 Section 3 Transverse Profile Parameters Set x b d Calculate x b c x d where i n 1 n 2 1 Note Sample code in C is available from TRL Limited demonstrating the iterative procedures to be followed in order to resample the transverse profile using the cubic spline Average profile The average profile is calculated from the arithmetic mean of valid re sampled transverse profiles within the averaging length Lave For a particular Lave averaging length the value of the average profile height at transverse location in the average profile is calculated using the number of transverse profiles within each averaging length Tave as follows
18. 0 2m after the previous step This approach to removal of false positives may also be applied to the removal of cracks over other predefined regions e g the centre of the survey width Removal of traffic sensors and other similar non crack features To identify false positive cracks arising from traffic sensors or other similar non crack features a process may be applied that examines the average angle of cracks directional continuity and the number of cracked grid cells within a continuous semi continuous crack The classification of false positive cracking considered to be the result of traffic sensor like features uses the following definitions A diagonal crack is a crack containing a number of continuous semi continuous cracked grid cells joined in a similar diagonal direction across the carriageway The starting grid cell of a diagonal crack is the first cracked cell identified in the diagonal crack The end grid cell of a diagonal crack is the final cracked cell identified in the diagonal crack The length of a diagonal crack L m is the sum of the cracked grid cells identified between and including the starting grid cell and the end grid cell multiplied by the grid size default 0 2m For example a diagonal crack containing 7 cracked grid cells would have a length L 7 x 0 2m 1 4m The height H m is the distance in the direction of travel between the starting grid cell and the end grid cell of
19. 0 5mm e 65 of the differences between the SMTD calculated from the measured Texture Profile and the SMTD calculated from the Reference Profile from the test site for the assessment of the measurement of SMTD fall within the range 0 13mm 119 SCANNER User Guide and Specification Volume 5 120 95 of the differences between the SMTD calculated from the measured Texture Profile and the SMTD calculated from the Reference Profile from the test site for the assessment of the measurement of SMTD fall within the range 0 25mm All of the differences between the SMTD calculated from the measured Texture Profile and the SMTD calculated from the Reference Profile from the test site for the assessment of the measurement of SMTD fall within the range 0 75mm 65 of the differences between the MPD calculated from the measured Texture Profile and the MPD calculated from the Reference Profile from the test site for the assessment of the measurement of MPD fall within the range 0 13mm 95 of the differences between the MPD calculated from the measured Texture Profile and the MPD calculated from the Reference Profile from the test site for the assessment of the measurement of MPD fall within the range 0 25mm All of the differences between the MPD calculated from the measured Texture Profile and the MPD calculated from the Reference Profile from the test site for the assessment of the measurement of MPD fall within the range 0
20. 75mm 8 10 8 10 1 8 10 2 8 10 3 8 10 4 8 10 5 Section 8 Accreditation Testing Site tests of Multiple Line Texture The Accreditation Tester selects one or more test sites for the assessment of the measurement of Multiple Line Texture measurements RMST marking the start and end of each section with a reflective post The site may contain both straight and curved Sections but will not contain any extremes of geometry The site may contain lengths with even texture across the width of the pavement and lengths where the texture depth present in the wheel tracks differs with that present in the centre of the pavement The Accreditation Tester measures the texture profile of the site using the Reference Method given in Table 8 1 for the measurement of Multiple Line Texture RMST The reference measurement will provide up to 25 measurements of RMST spaced evenly across a survey width of 3 6m The reference data will be reported as Mean Nearside RMST Mean Middle RMST and Mean Offside RMST over 10m lengths Each of these values will be obtained as the mean of at least 3 multiple line texture measurements obtained in the Nearside Middle and Offside of the survey width The Contractor defines a survey route appropriate for the survey of the test site carries out one or more surveys of the test site as required by the Accreditation Tester and delivers the SCANNER RCD and the SCANNER HMDIF files to the Accreditat
21. Accreditation AS SSIINGE sc seseti a ecien ct dapat aaecchte ede ete eee 136 11 1 General requirements a cssnes actin ei eee te 136 Annex 1 Identifying False Cracks ccccesssecceeeeeesseeeeeeeeeeseeaeeeeeeeensneeaeees 138 12 1 Removal of false positives from the edge of survey data 00 138 12 2 Removal of traffic sensors and other similar non crack features 139 Annex 2 Other Visible Detects ac ncseyssescteiec sees ties opeeeaoeteeoesereuayededevesBevens lee 143 13 1 General FOCI CIS sae site cides cen csils raciceesauatlotives wbleusabineis tacuaby Hracepeeeageeu 143 Survey Parameters and Accreditation Foreword This document is one of a series of five describing the requirements for SCANNER Surveys Surface Condition Assessment of the National Network of Roads It replaces the revised SCANNER specification first published in March 2006 and updates the draft SCANNER specification first published in February 2007 The five Volumes are 1 Introduction to SCANNER surveys 2 Advice to Local Authorities Procuring Surveys 3 Advice to Local Authorities Using SCANNER Survey Results 4 Technical requirements SCANNER Survey Data and Quality Assurance 5 Technical requirements SCANNER Survey Parameters and Accreditation This volume 5 Technical requirements for SCANNER Survey Parameters and Accreditation defines the technical requirements for the parameters provided by the machine
22. Accreditation Tester 133 SCANNER User Guide and Specification Volume 5 10 10 1 10 1 1 10 1 2 10 1 3 10 1 4 10 1 5 10 2 10 2 1 10 2 2 10 2 3 134 Consistency Tests General requirements The Consistency Tests measure the repeatability of the Equipment in the measurement and reporting of the parameters and the reproducibility between different survey equipment The overall consistency of the Equipment is reported in terms of the bias and random error present in the reported SCANNER Road Condition Indicator The Consistency Tests will be carried out on all survey equipment at as near as possible the same time of year This will normally be as part of the annual Accreditation re testing When new survey equipment is accredited at a different time of the year the Tester will award a provisional consistency score based on the predefined sample road network and re tested at the next annual re accreditation tests The machine developer or Contractor attends the Consistency Tests and carries out any surveys or data processing required by the Tester at its own cost The Equipment is driven and operated by drivers and operators named in the Contractor s quality system The Tester supervises and controls the tests The Consistency Testing is carried out on a predefined road network which includes representative samples of the road networks for which the Equipment is required Consistency Tests The Accredi
23. Offside RMST 0 25mm 0 75mm Cracking Intensity 75 N A Other Visual Defects No requirement No requirement Table 8 3 Tolerances for network level evaluation 130 Section 8 Accreditation Testing Notes for Table 8 3 1 The Accreditation Tester calculates National Grid Co ordinates and altitude of Section Start Point from the SCANNER RCD and or HMDIF and compares them with the Reference co ordinates 90 of the positions obtained from the SCANNER RCD and or HMDIF must fall within the required tolerance of the reference position For those Sections start points for which National Grid Co ordinates and altitude were provided by the Accreditation Tester the reference position is the National Grid Co ordinates and altitude provided by the Accreditation Tester For the remaining Section start points the reference position is the National Grid Co ordinates and altitude of the Section start point recorded in the Reference Survey National Grid Co ordinates and altitude where signal availability gt 70 over each 100m length National Grid Co ordinates and altitude where signal availability lt 70 over each 100m length The tolerance for 3m and 10m Moving Average and Enhanced Longitudinal Profile are in terms of the differences or fractional errors between the Moving Average or Enhanced Longitudinal Profile Variances calculated from the measured profile and the Moving Average or Enhanced Longitudinal
24. Value of 1 Remaining lengths are reported to have a Bump Value of 0 The principles described in paragraphs 2 3 7 through 2 3 9 also apply when calculating the Bump Measure i e The extra readings in this case lying at the end of any 1m length are used in applying the Central Difference Method however P and P need not be calculated for those points and are not considered when determining the maximum absolute values F and F When a reading falls exactly on the boundary between two 1m lengths it is deemed to lie within the former of those lengths At the start and end of the survey there will be lengths over which it is not possible to calculate Pj and Pj Reporting lengths that include these are considered invalid and therefore not reported in the HMDIF file 17 SCANNER User Guide and Specification Volume 5 2 6 2 6 1 18 Typical Values Checks and Limits Typical values to be confirmed during acceptance tests for the checks and limits to be placed on the longitudinal profile data are given in Table 2 2 Parameter Typical Value Minimum speed for 3m LPV 3m ELPV and bump 20 km h measure km h Maximum speed for 3m LPV 3m ELPV and bump 120 km h measure km h Maximum number of invalid speeds within 3m LPV 5 3m ELPV and bump measure averaging length Minimum speed for 10m LPV and 10m ELPV km h 20 km h Maximum speed for 10m LPV and 10m ELPV 120
25. and 3m Enhanced Longitudinal Profile Variance over any length L are considered invalid and therefore not reported in the HMDIF file if the percentage of speed values recorded over that length as below V3 exceeds a predefined limit typically 5 The 10m moving average Longitudinal Profile Variance and 10m Enhanced Longitudinal Profile Variance over any length L are considered invalid and therefore not reported in the HMDIF file if the percentage of speed values recorded over that length as below Vip exceeds a predefined limit typically 5 Checking survey acceleration and deceleration The speed values are averaged over each reporting length the default is 10m and the following relationship is applied 2s where v is average speed over the reporting length u is average speed over the preceding reporting length a is the acceleration and s is the reporting length over which the speed changed from u to v ais then expressed as the absolute acceleration aaps The absolute acceleration at the start of the survey is assumed to be zero as there is no previous value of u although this should not affect the data if there has been a run in before the start of the first section For each 10m reporting length the maximum absolute value of acceleration is calculated Amax measured in the length Lrecovery before the end of that reporting length For example if Lrecovery 70m then at d 200m the end of
26. be calculated using moving average sensor measurements calculated for points 1 through 100 the second using points 101 through 200 and the last 100th using points 9001 through 10000 Where the baseline length is not an exact multiple of the interval between texture profile point readings or the reporting length is not an exact multiple of the baseline length there will be more moving average sensor measurements than required within some reporting lengths e g With a reporting length of 10m a baseline length of 0 1m and an interval between texture profile point readings of 0 0009925m nwill be calculated as 0 1 0 0009925 100 75567 rounded to 100 and J will be calculated as 10 100 0 0009925 100 75567 rounded down to 100 The number of moving average sensor measurements used for the calculations within a reporting length will therefore be 100 100 10 000 However the number of measured texture profile points lying within each 10m reporting length will be as shown in Table 5 1 Reporting Length Number of Readings 0 10 10 075 10 20 10 076 20 30 10 075 30 40 10 076 40 50 10 075 Etc Table 5 1 Reporting lengths versus number of readings 5 4 17 5 4 18 5 5 5 5 1 Section 5 Texture Profile Parameters In such situations the extra measured texture profile point readings at the end of the reporting lengths are used in calculating
27. e Figure 3 11 lower shows that there is a point D12 corresponding to point Ds that satisfies the stated criteria all points from D4 to Dig inclusive lie either on or below the line of length L from point D3 45 SCANNER User Guide and Specification Volume 5 3 6 25 3 6 26 46 passing through point D12 This therefore represents the correct position for the notional straight edge If no pair of points can be found that satisfies the stated criteria the nearside cleaned rut depth is set to zero Calculation of depth and offset to each intervening point The depth d and offset I of each point lying between Dn and Dp relative to the notional straight edge can be calculated as follows S fyny x h V ve Yn x x _ x an D ya d S y y x x y y a n x x L h d Xn Yn Offset and height within transverse profile of point Dn Xp Yp Offset and height within transverse profile of point Dp Xa Ya Offset and height within transverse profile of point Da Xa Y a Offset and height within transverse profile of the point on the notional straight edge vertically above point Da 3 6 27 3 6 28 3 6 29 Section 3 Transverse Profile Parameters XoY Xa Ya S 2 Gay i Xaya D Figure 3 12 Definition of rut depth Calculation of cleaned nearside rut depth The cleaned rut depth Rut sc is calculated as the
28. each diagonal crack The width W m is the distance in the direction transverse to the direction of travel between the starting grid cell and the end grid cell of each diagonal crack NOTE THIS SHOULD ALWAYS BE POSITIVE The average angle A degrees between the start and end cell of each diagonal crack is determined by A tan H W The number of steps for each diagonal crack S unitless is defined as the number of occurrences within a full scan detailed 139 SCANNER User Guide and Specification Volume 5 12 2 3 12 2 4 140 in the classification rules below where there is an increase in the direction of travel from one cracked grid cell to the next For example in Figure 12 2 there are 6 occurrences in the diagonal where there is an increase in the direction of travel between neighbouring cracks The classification of false positive cracking considered to be the result of traffic sensor like features should be carried out using the following configurable parameters The length required to reclassify all cracks within the diagonal crack as false positive default 1 4m The angle required to reclassify all cracks within the diagonal crack as false positive default between 17 and 70 The step required to reclassify all cracks within the diagonal crack as false positive default 3 The identification of false positive cracking considered to be the result of traffic sensor like features uses the
29. following approach Commencing at the start of the survey examine each grid cell containing cracking For the first grid cell containing cracking record the location of the grid cell and search surrounding cells in a NE or NW direction where North is the direction of travel For grid cells located in the nearside of the carriageway on or to the left of the centre line commence a full diagonal search in the NE direction and for grid cells located in the offside of the carriageway to the right of the centre line commence a full diagonal search in a NW direction The search pattern is shown in Figure 12 1 If a further cracked grid cell is identified in the search then store the position of the grid cell with the position previously recorded for the starting grid cell Commence a new search in the same direction from this grid cell to identify the next cracked grid cell Continue until searching fails to identify further cracked grid cells The stored data now describes the location of grid cells forming part of a traffic sensor or diagonal feature For this feature determine the starting grid cell the end grid cell the length L the Height H the Width W the Angle A and the number of steps S If the length L angle A and step criteria S are satisfied then the grid cells have been positively identified to belong to a traffic sensor or diagonal feature All grid cells within the diagonal crack should be reclassified as false pos
30. it approaches the line or corner Where a crack runs exactly alone a line between grid cells or along the edge of the grid the principles shown in Figure 6 3 are applied A crack is only considered to be within the cell s immediately above or to the right of the line except where it runs exactly along the right hand side of the grid or at the end of the survey in which case it is considered to be within the cell s immediately to the left or below respectively 77 SCANNER User Guide and Specification Volume 5 6 cells A S 39 9 a Cell consider as not containing crack Cell considered as containing crack Figure 6 2 Classification of grid cells containing cracks 1 End of the survey Ee Cell considered as containing crack r lt Cell consider as not containing crack Start of the survey Figure 6 3 Classification of grid cells containing cracks 2 78 6 5 6 5 1 6 5 2 6 5 3 6 6 6 6 1 6 6 2 6 6 3 6 6 4 Section 6 Cracking Parameters Carriageway Cracking Intensity The carriageway cracking intensity is expressed as the percentage of the cracked grid cells The calculation of carriageway cracking intensity is carried out using the following configurable parameters Length over which the cracking intensities are to be calculated and reported typically 10m which shall be an integer multiple of the length of each grid cell The carriageway cracking intensity is expre
31. km h km h Maximum number of invalid speeds within 10m LPV 5 and 10m ELPV averaging length Acceleration effective length m 70m Acceleration threshold 3m LPV 3m ELPV and 3ms bump measure ms 7 Acceleration threshold 10m LPV and 10m ELPV 2ms Table 2 2 Limits for the calculation of longitudinal profile parameters 3 1 3 1 1 3 1 2 3 2 3 2 1 Section 3 Transverse Profile Parameters Transverse Profile Parameters General Requirements The following parameters will be derived from the transverse profile and delivered in the HMDIF file Transverse profile unevenness Cleaned rut depth nearside and offside Edge Roughness Road Edge Step Transverse Variance These parameters are calculated from the measured transverse profile data before any fitting is carried out on the Survey Data e g fitting to the Employer s network Before the parameters are calculated checks must be carried out on the validity of the transverse profile as described in Section 3 2 The calculation of the transverse profile parameters is carried out in a step by step process outlined in Figure 3 1 Checking the transverse profile If any single profile point within a transverse profile is invalid i e outside the permitted range that profile is also defined as invalid and is not used in calculation of the parameters described in the following sections If more than a defined percentage typic
32. of Curvature Radius of Curvature Calibrated Measuring wheel Steel Tape Longitudinal Longitudinal Profile Measured Longitudinal ARRB Walking Profiler and or Profile Profile in both wheelpaths Artificial Profile characterised using micrometer and or rod and level Variance 3m 10m Variance both ARRB Walking Profiler wheelpaths Transverse Transverse Profile Measured Transverse Artificial Profile transverse profile profile Profile measured over the road edge Cleaned Rut Depth HARRIS 1 with manual assessment of the measured transverse profiles Rutting Rut Depth Rut depth Straight edge and wedge and or HARRIS 1 with manual assessment of the measured transverse profiles Texture Texture Profile Measured Texture Profile Characterised Artificial Profile Profile Sensor Measured Sensor Measured HARRIS 1 Texture Depth Texture Depth SMTD SMTD and Mean Profile Depth MPD Multiple Line Texture RMST HARRIS 1 Cracking Crack Intensity Crack Intensity Primary Reference Data Manual Assessment of Digital Images Crack Intensity Crack Intensity Secondary Reference Data Mean Crack Intensity Recorded by each item of Equipment 2 Crack map Individual Cracked Grid tiles Manual Assessment of Digital Images 1 Highways Agency Road Research Information System HARRIS1 HARRIS2 2 Where more than one piece of Equipment from different Contractors participate in the Tests Table 8 1 Refer
33. point co incident with a laser position the nearest re sampled point to the right of each laser position is used This procedure is carried out as follows Determine the original laser location x that satisfies Xa lt Xe and Xas1 gt Xe Determine the original laser location Xg that satisfies xg lt Xa 1000mm and XBu1 gt Xa 1000mm Evaluate slope corresponding to each original laser location Xi from i A to i B 1 A and B determined above as follows slope F a a an Note that slope is calculated with y x and t expressed in the same units and where j4 and je are the indexes for the re sampled points corresponding to the measurement laser positions as follows Xaa lt Kis Xj Z Xir Xaa lt Xis a 2 Xin The edge position esp is adjusted further as esp x where X lt Xim Xj 2 Xi1 Where i is the largest value between A and B 1 inclusive for which the value slope is greater than 0 11 If no value of slope exceeds 0 11 for the values of i evaluated the value egp is not adjusted The best transverse profile now takes the value at Yp as its first value J ar O N Puy I y 0 i N P Nel ebp Locate the road edge in each transverse profile in the average length Once epp the road edge in the best transverse profile has been located this is used to locate en the road edge in each valid transverse profile which was used to obtain the best tra
34. reporting length 190 to 200 Amax200 is the maximum acceleration calculated between d 130 and d 200 i e the maximum value Of abs140 abs150 abs200 At the start of the survey there may not be sufficient data for a length of Lrecovery before the current point so the length is reduced as appropriate For example if Lrecovery 70m at d 30 only the accelerations over the first 30m are checked i e the maximum value Of absi0 abs20 Aabs30 The bump measure 3m moving average Longitudinal Profile Variance and 3m Enhanced Longitudinal Profile Variance over any reporting length L are considered invalid and therefore not reported in the HMDIF file if amax gt Amax3 at the end of that reporting length as absolute acceleration 11 SCANNER User Guide and Specification Volume 5 2 2 12 2 3 2 3 1 2 3 2 2 3 3 2 3 4 12 is used and as the acceleration and deceleration thresholds are the same only one check is made The 10m moving average Longitudinal Profile Variance and 10m Enhanced Longitudinal Profile Variance over any reporting length L are considered invalid and therefore not reported in the HMDIF file if amax gt Amaxio at the end of that reporting length As absolute acceleration is used and as the acceleration and deceleration thresholds are the same only one check is made Moving Average Longitudinal Profile Variance The moving average longitudinal profile variance is calculated as follows Th
35. rounded down to the nearest integer For y lt 0 find the maximum value of y in the range p7 to pwve 1 If that maximum value is more than y Pa is set to the location of that maximum value If the maximum value is NOT more than y Pais set to pawe 2 rounded down to the nearest integer For locating minimum and maximum derivative values below a minimum absolute value Q is applied so that derivative values of smaller magnitudes are ignored Xfbx Note a value of Q 0 00025mm should be used 3 4 24 3 4 25 Section 3 Transverse Profile Parameters Find the sign of the second derivative of the transverse profile at position Pa If the second derivative at pa is negative Look for the minimum second derivative with a value lower than Q occurring within the interval p2 to prs inclusive where puss is the index for re sampled position N 3 rounded down to the nearest integer Define p as the position at which the minimum second derivative y with a value lower than Q from p2 to pws occurs If such a minimum is not found Pp 0 Look for the maximum second derivative y with value higher than Q to the right of pp b between position pp and pns Let the position at which the maximum second derivative with value higher than Q between position pp and pnas occurs be pe If such a maximum is not found pe 0 and Q is used for the ratio calculation described in 3 4 19 Find th
36. should have a default value of 3 but which should be parameterised in the software The calculated value of m should be rounded up to the next even integer There are m 1 high pass coefficients bhp The values of bhp are initially determined by bhp H sinc 2 tr fL A for i m 2 m 2 1 m 2 where H are the coefficients of a Hamming window given by 2 4 4 2 4 5 2 4 6 2 4 7 2 4 8 Section 2 Longitudinal profile parameters H 0 54 0 46 cos 2 m i m 2 m sinc x sin x x if x 0 OR sinc x 1 if x 0 e T 3 14159 f is expressed in the same units as 1 A and the trigonometric functions are defined such that the arguments are in radians The coefficients bhp are then normalised as bh f m 2 bhp Pi Where n bhp n i i m 2 Following the normalisation of the coefficients the following transformation is performed bhp bhp for i m 2 m 2 1 1 and i 1 m 2 bhp 1 bhp for i 0 The value of the filtered longitudinal profile height z at each position i is obtained by multiplying the profile heights between Z i m 2 and Zi m 2 by the corresponding m 1 filter coefficients and then summing the resulting products Hence m 2 a pan bhp j m 2 Enhanced Variance The Enhanced Variance is calculated as 1 N Enhanced Variance es where 1 N is the number of filtered profile points within each reporting length
37. testing and reporting The purpose of accreditation RE TESTING is to ensure that the Equipment continues to comply with the requirements of the SCANNER specification including any requirements that may have changed since the previous test So that the Employer may have confidence that the Equipment and its driver and operator continue to be capable of producing accurate consistent and reliable results under standardised test conditions Section 11 defines the requirements for accreditation re testing SCANNER User Guide and Specification Volume 5 2 2 1 2 1 1 2 2 2 2 1 2 2 4 2 2 4 10 Longitudinal Profile Parameters General requirements The following parameters will be derived from the longitudinal profile data and delivered in the HMDIF file Moving average longitudinal profile variance in each wheelpath Enhanced longitudinal profile variance in each wheelpath Bump measure in each wheelpath These parameters are calculated from the measured longitudinal profile data before any fitting is carried out on the Survey Data e g fitting to the Employer s network Before the parameters are calculated checks must be carried out on the validity of the longitudinal profile as described in Section 2 2 Following the checking of the validity of the longitudinal profile data the parameters are calculated from the longitudinal profile data separately i e the input data to the calculation of each parameter mo
38. that length was invalid i e with an offset length or angle outside the permitted ranges Cleaning the cracking data Cleaning of the cracking data is the process of identifying grid cells that arise from the false positive identification of cracks Survey contractors are required to demonstrate that their systems remove false positive measurements of cracking effectively Illustrative methods to remove false positive cracked grid cells arising from the edges of survey width and arising from traffic sensors are described in Annex 1 Note that the methods given in Annex 1 apply cleaning to crack grids and therefore do not assist in the cleaning of crack data for the calculation of wheeltrack cracking given in section 6 8 75 SCANNER User Guide and Specification Volume 5 6 3 2 6 4 6 4 1 76 Following removal of the false grid cells the carriageway cracking intensity transverse cracking intensity and surface deterioration intensity can be calculated noting that There may be a need to provide multiple values of whole carriageway cracking intensity For example a For the full measurement width b For a reduced measurement width e g 2 4m c With and without removal of false positives using the cleaning algorithms Therefore processes for checking cleaning and reporting cracking data should be developed with variable parameters wherever possible rather than simply with fixed parameters Ob
39. the largest step upwards from the best fit line in the verge region of the profile and the value Smin is the largest step downwards from the best fit line in the verge region of the profile Smin will have a negative value if a downwards step exists from the road to the verge The transverse position where Smax Occurs is defined as Pmax and the position where Smin occurs is defined as Pmin In Figure 3 14 Pmax Xo Pmin X2 If Smax 0 Pmax 0 If Smin 0 Pmin O The step height S is S Smax if Pmax gt Pmin OR S Smax if Pmax Pmin 0 AND Smax gt 0 S Smin if Pain gt Pmax OR S Smi if Pmin Pmax 0 AND Smin lt 0 S Oif Pmin Pmax 0 AND Smax Smin 0 S is given the value S 0 for any invalid transverse profile or where the road edge position en is reported as 0 indicating that no edge was found within the profile Reporting the edge step height For the reporting length The number of downward steps between 20mm and 50mm including steps of 50mm but excluding steps of 20mm exactly 50mm lt S lt 20mm is denoted as S44 53 SCANNER User Guide and Specification Volume 5 3 9 3 9 1 3 9 5 3 9 6 54 The number of downward steps greater than 50mm S lt 50mm is denoted as Sie Small step down at the road edge is reported as Ls_1 where Ls 100 S1 Te Large step down at the road edge is reported as Ls 2 whe
40. up to n characters including the decimal point and an optional leading sign or with d digits after the decimal point right justified and padded with spaces Route header data Record R1 1 Single record as defined in Table 7 1 Characters Description Format Value range 1 8 SCNROUTE A8 9 58 Route identifier A50 59 63 Number of survey lanes within I5 1 99999 the route Table 7 1 Record R1 1 Route Header File 87 SCANNER User Guide and Specification Volume 5 Survey Lanes 7 1 6 Record R2 1 Repeated for each survey lane as defined in record R1 1 sorted in sequence through the route as defined in Table 7 2 below Characters Description Format Value range 1 30 Section label blank for a A30 dummy survey lane see Note 1 below 31 41 Section length measured in F11 3 0 000 to metres 9999999 999 42 61 Start Node label i e node at A20 the end of the section from which the survey starts 62 64 Cross section position XSP A3 See UKPMS code of the lane see Note 2 documentation below 65 75 Start Node x co ordinate if F11 3 0 000 to known 9999999 999 76 86 Start Node y co ordinate if F11 3 0 000 to known 9999999 999 87 186 Section description see Note 3 A100 Table 7 2 Record R2 1 Survey lanes Note 1 A dummy survey lane requires only a Start Node label normally set to the
41. where RMST is the mean RMST value calculated by averaging the valid individual RMST values from all texture measurement lines over the nearside wheel path using the approach described for the mean nearside RMST paragraph 5 5 12 N is the number of valid individual RMST values from all measurement lines in the nearside wheel path in the texture variability reporting length L RMST is the jth valid individual RMST value from all measurement lines in the nearside wheel path in the texture variability reporting length L Invalid individual RMST values are not included in the summation and Nval is the number of valid Summed individual RMST values in the nearside wheel path L has a typical value of 10m but should be parameterised L will always be an exact integer multiple of Lams Middle RMST Variance Middle RMST Variance values are calculated from the valid individual RMST values from texture measurement lines lying within a distance of 0 3m inclusive of the nominal line mid way between the nearside and offside wheel paths using the approach described above for the nearside RMST Variance Offside RMST Variance Offside RMST Variance values are calculated from the valid individual RMST values from texture measurement lines lying within a distance of 0 3m inclusive of the offside wheel path using the approach described above for the nearside RMST Variance Texture variability The textur
42. 1 The Contractor defines a survey route appropriate for the survey of the test site The Accreditation Tester provides the Contractor with a breakdown of the range of speeds for which longitudinal profile measurements of the site will be required A number of test surveys are carried out at constant survey speed and a number of test surveys are carried out under conditions of deceleration To achieve even decelerations the Accreditation Tester marks out the test site to indicate the locations at which survey vehicle braking should start and end The Contractor uses the survey equipment to collect measurements of Longitudinal Profile on the test site under the range of conditions defined by the Accreditation Tester and delivers the SCANNER RCD and the SCANNER HMDIF files from the test site to the Accreditation Tester The measurement of Longitudinal Profile measured by the survey equipment over the test site and provided in the SCANNER RCD is assessed as follows A moving average filter is applied to both the Reference Profile and the measured profile to obtain two filtered profiles for which wavelengths in excess of 3m and 10m have been attenuated If required the Accreditation Tester normalises the measured profile for example to remove any constant or linear offset between the Reference and measured profiles The Accreditation Tester calculates the differences between the filtered Reference Profile and the filtered
43. 1 3 0 000 to survey data measured in metres 9999999 999 66 74 z co ordinate at the end of the F9 3 9999 999 to survey data measured in metres 9999 999 75 75 End of survey co ordinate status I1 0to2 Table 7 6 Record S1 3 Single Record Survey Header Data 7 4 10 Section 8 Data File Formats Note Each set of co ordinates is accompanied by a Status Status values have the following meanings 0 GPS signal available values meet accuracy requirements 1 GPS signal unavailable values meet accuracy requirements 2 Values do not meet accuracy requirements Record 1 4 Single Record Characters Description Format Value range 1 5 Number of nodes identified I5 0 to 99999 during the survey run 6 17 Chainage interval between F12 9 0 000000000 geometric measurements to measured in metres see note 99 999999999 1 below 18 29 Chainage interval between F12 9 0 000000000 nearside and offside longitudinal to profile points and associated 99 999999999 speeds measured in metres see note 1 below 30 35 Offset of nearside longitudinal F6 3 9 999 to profile points measured in 9 999 metres from the centre of the survey vehicle negative to the left 36 41 Offset of offside longitudinal F6 3 9 999 to profile points measured in 9 999 metres from the centre of the survey vehicle negative to the left 42 53 Cha
44. 10 5 4 11 5 4 12 5 4 13 5 4 14 Section 5 Texture Profile Parameters For k T tok T os ge y DY l j T i 1 where 1 7 k 2 1 For each successive baseline length a regression line is calculated as y aitb where iranges from 1 to n over the baseline length D Sr 1 o1 Aa n n 1 a pads I An jad eat a 5S y moving average sensor measurement at point within the baseline length For each point within the baseline length an adjusted moving average sensor measurement is calculated as Y ai b The maximum value of Y is determined within each half of the baseline giving Vs and Yonu 3 and the average value is calculated as Y 3 lt i l The individual MPD value over the baseline is calculated as Y Y MP D Bmaxl 3 Bmax2 _ Y The MPD value averaged over length L is given by 1 J MPD AES val i 1 65 SCANNER User Guide and Specification Volume 5 5 4 15 5 4 16 66 where MPDg values are calculated for successive baseline lengths within the reporting length any invalid MPDg values are excluded from the summation and Jval is the number of valid MPDg values summed e g With texture profile points at exactly 0 001m interval a baseline length of 0 1m and an averaging length of 10m if the texture profile point at the start of the length L was numbered 1 the first MPDg would
45. 8 the edge roughness calculated from the Reference Transverse Profile fall within 0 025 95 of the differences between the edge roughness calculated from the measured Transverse Profile over 10m lengths and the edge roughness calculated from the Reference Transverse Profile fall within 0 05 Wheel path ruts The Accreditation Tester selects a test site and divides it into a number of Sections marking the start and end of each section with a reflective post The Accreditation Tester provides the Contractor with a map showing the location of the sites and the description of each Section start and end point on each site The sites may cover a broad range of rut depths and other transverse features The Accreditation Tester measures the rutting present on the test sites using the Reference Method given in Table 8 1 The Contractor defines a survey route appropriate for the survey of each of the test sites carries out one or more surveys of the test sites as required by the Accreditation Tester and delivers the SCANNER RCD and the SCANNER HMDIF files to the Accreditation Tester The Accreditation Tester averages the rut depths recorded in the SCANNER HMDIF over 10m lengths and subtracts them from the rut depths measured with the Reference Method over 10m lengths The test is passed if all the following criteria are met 65 of the differences between the measured maximum Rut Depths in each Wheelpath and the Refer
46. CD is required to enable the Accreditation tester and the Auditor to investigate the performance of the Equipment in the measurement of the Survey Data in detail The other format Highway Management Data Interchange Format HMDIF is required to deliver the data to the client for loading into a UKPMS accredited pavement management system Section 7 defines the RCD file format The requirements for HMDIF files are specified as part of UKPMS and the most recent definition may be found on the UKPMS website Accreditation and Consistency The purpose of ACCREDITATION testing is to ensure that the systems for data collection and data processing comply with the requirements of 1 3 2 Section 1 Introduction the SCANNER specification This should give the Employer confidence that the Equipment and its driver and operator are capable of producing accurate consistent and reliable results under standardised test conditions Section 8 and 9 define the requirements for Accreditation testing The purpose of CONSISTENCY testing is to measure the repeatability of each machine and the reproducibility between different survey machines so that accredited SCANNER survey results may be reported with confidence intervals error bands and used for reporting road condition for both national statistical purposes NRMCS SRMCS and local performance monitoring purposes BVPI SPI LTP and CPA Section 10 defines the requirements for Consistency
47. Profile Depth 5 4 3 5 4 4 5 4 5 5 4 6 Section 5 Texture Profile Parameters The ISO standard states that the MPD for an individual profile is determined as the arithmetically averaged two peak levels minus the average profile level over a baseline of 100mm 10mm length of road as illustrated in Figure 5 1 Mean Profile Depth MPD Average Level First half of baseline Second half of baseline Baseline Figure 5 1 Illustration of the levels used for the calculation of the MPD Before determining the peak and average levels from the texture profile points short wavelengths are removed by calculating a 5mm moving average for each individual profile point Slope suppression is then applied to the profile as a whole within the 100mm baseline length by calculating the regression line through all the moving average profile values and subtracting this line from the profile Valid MPD values obtained from successive 100mm lengths are finally averaged over a reporting length typically 10m to give the required average MPD Note The values of 0 005m for the moving average 0 1m for the baseline and 10m for the averaging length should be parameterised Calculation of MPD The number of profile points corresponding to a moving average length M typically 0 005m is calculated as M m Fa rounded to the nearest odd integer exact even numbers rounded up where inte
48. Profile Variances calculated from the Reference Profile as described in Volume 4 The tolerance for the detection of Cracking Intensity is the minimum percentage of sub sections that the survey data show to contain high or low levels of Cracking Intensity that are also shown to contain high or low levels of Cracking Intensity in the Reference Data Cracking Intensity is assessed over selected test Sections using a similar method to that described for the Site Tests Whichever is greater Whichever is smaller Table 8 4 Notes for Table 8 3 131 SCANNER User Guide and Specification Volume 5 9 9 1 9 1 1 9 1 2 132 survey Data Accreditation Testing General requirements In addition to checking that the survey data successfully meets the requirements of both the Site Tests and the Network Tests the data output from the Survey Equipment is checked to ensure that All specified checks have been carried out on the survey data as defined in Sections 1 to 7 The data complies with all the requirements for loading into a UKPMS accredited system The Accreditation Tester provides the Contractor with test datasets as RCD and Route Files for the purpose of testing the data processing systems employed by the Contractor for the generation of HMDIF files The Contractor processes the RCD files and provides the resulting HMDIF files to the Accreditation Tester The Accreditation Tester Checks t
49. ROADS UK ROADS BOARD SCANNER surveys for Local Roads User Guide and Specification Volume 5 Technical Requirements for SCANNER Survey Parameters and Accreditation Version 1 0 2009 Edition SCANNER User Guide and Specification Volume 5 Contents Amendment Record This report has been issued and amended as follows Issue Revision Description Date Signed 0 0 12 Revised format and 14 12 07 K A Gallagher amendments 0 13 Detailed amendments 21 11 08 P Werro 0 0 14 TRL Review 23 01 09 A Wright 0 0 15 After review by SCANNER 09 10 09 P Werro stakeholders 1 0 0 Published Version 09 10 09 KA Gallagher Department for Transport Great Minster House 76 Marsham Street London SW1P 4DR Telephone 44 0 207 944 8300 Website www dft gov uk Survey Parameters and Accreditation Acknowledgement This SCANNER User Guide has been developed from the SCANNER specification used in 2005 06 and 2006 07 It incorporates many detailed changes based on experience of using the SCANNER specification in 2005 06 and 2006 07 the TTS specification before that in 2003 04 and 2004 05 and a wide range of comments from interested parties It includes the results of research on developing SCANNER commissioned on behalf of the UK Roads Board The previous SCANNER specifications were based on the original TRACS Type Surveys for the Principal Road Network Specification and Advice Note produced for the UK Roads Board by the Chris Britto
50. S 115 36 4 52 D 68 T 84 d 100 t 116 37 5 53 E 69 U 85 e 101 u 117 amp 38 6 54 F 70 V 86 f 102 V 118 39 7 55 G 71 W 87 g 103 Ww 119 40 8 56 H 72 X 88 h 104 x 120 41 9 57 l 73 Y 89 i 105 y 121 42 58 J 74 Z 90 j 106 Z 122 43 s 59 K 75 91 k 107 123 44 lt 60 L 76 92 l 108 124 45 61 M 77 93 m 109 125 46 gt 62 N 78 a 94 n 110 126 47 63 O 79 _ 95 o 111 Table 7 18 SCANNER RCD Character Set 7 5 2 Each record is terminated by ASCII carriage return and line feed characters which have decimal codes 13 and 10 respectively 103 SCANNER User Guide and Specification Volume 5 7 6 SCANNER Format Definitions 7 6 1 In the formal definitions the following notation and terminology are used means or space means ASCII character code 32 letter means any alphabetic character A Z a z digit means 0 1 2 3 4 5 6 7 8 9 others means any printable character as defined in Table 7 18 with the exception of space letters and digits ay means a may appear n to m times a means a will appear n times 7 6 2 An means a string of n characters without leading spaces or a string of n spaces More formally letter digit others letter digit others space space 7 6 3 In means an integer numeric field of up to n characters including an optional leading sign right justified and padded with leading spaces More f
51. The Accreditation Tester calculates a single average Cracking Intensity for each 50 m sub section from the Cracking Intensities provided by each set of survey equipment These average Cracking Intensities are the Secondary Reference Data The Accreditation Tester compares the Cracking Intensities obtained from the SCANNER RCD provided by each Contractor with the Secondary Reference Data The Accreditation Tester identifies any significant local differences between the Cracking Intensities obtained from the SCANNER RCD provided by each Contractor and the Secondary Reference Data The Accreditation Tester may require the Contractor to investigate and explain the reasons for these differences If the difference arises from an apparent deficiency in the Contractor s Equipment the Accreditation Tester may require the Contractor to make improvements or may impose restrictions such as those described in section 8 11 18 The Accreditation Tester evaluates the differences between the general sensitivity of the Equipment and the Secondary Reference Data The comparison with the Secondary Reference Data may enable the Accreditation Tester to estimate a sensitivity factor for the Equipment so that the Cracking Intensities reported by the Equipment can be correlated 8 11 23 8 13 3 Section 8 Accreditation Testing with the Cracking Intensities reported by Equipment provided by other Contractors Where this is possibl
52. ally 25 of the profiles within a reporting length is invalid the parameters calculated for that reporting length are considered invalid and therefore not reported in the HMDIF file 19 SCANNER User Guide and Specification Volume 5 20 a Identify the road edge within each transverse profile to generate cleaned transverse profile data ea b Calculate the transverse unevenness within each cleaned transverse profile Sa c Calculate the rut depths within each cleaned transverse profile the cleaned rut depths d Calculate the severity of road edge roughness using the measured transverse profile data along with the road edge location generated when cleaning the transverse profile Rau e Calculate the step heights at the road edge using the measured transverse profile data along with the road edge location generated when cleaning the transverse profile when cleaning the transverse profile za f Calculate the transverse variance using the cleaned transverse profiles na g Calculate the coverage the percentage of transverse profiles over which an edge was identified Figure 3 1 Calculation of the transverse profile parameters 3 3 3 3 1 3 3 2 Section 3 Transverse Profile Parameters Definitions The following definitions apply in the calculation of the transverse profile parameters except where specific local definitions are provided Transvers
53. and Secondary Reference Data The Primary Reference Data forms the basis for initial assessment of the performance of the Equipment as described in the following paragraphs 8 11 4 to 8 11 14 The Accreditation Tester derives the Primary Reference Data by visual inspection of digital images The Highways Agency Road Research Information System HARRIS survey vehicle provides the images from which the Primary Reference Data are derived as follows The HARRIS survey vehicle provides greyscale images 256 levels of the test sites over a survey width of approximately 2 9m at an image resolution of approximately 2mm longitudinally and 2mm transversely The HARRIS images are displayed in a strip map format on a computer screen for visual inspection The images are marked with a 200mm square grid Note the outermost grid square will therefore be only partially occupied The grid marked images are inspected by eye to identify cracking Any grid tile containing a crack is counted The total number of grid tiles with a crack is counted over each 50m length of survey data The Accreditation Tester calculates the Cracking Intensity as the percentage of 200 mm square grid tiles with a crack over each 50m sub section length which is the Primary Reference Data The Accreditation Tester interprets the Primary Reference Data to obtain the Relative Normalised Cracking Intensity for each sub section The Accreditation Tester calcula
54. andard deviation of the Cracking Intensity for each sub section The Accreditation Tester classifies the sub sections in the same way as the Primary Reference Data to obtain the Relative Normalised Cracking Intensities for the survey data provided by the Contractor The Accreditation Tester compares the Primary Reference Data with the results of the surveys carried out by the Contractor Each survey run is treated separately so that if there are two survey runs two sets of Relative Cracking Intensities will be compared with the Primary Reference Data The Accreditation Tester assesses the accuracy of the measurement of cracking using the Primary Reference Data The Accreditation Tester identifies the 50m sub sections containing a high level of cracking in the Primary Reference Data The Accreditation Tester compares the results of the survey carried out by the Contractor using the Equipment over the same sub sections with the Primary Reference Data The Accreditation Tester identifies the 50m sub sections containing a moderate level of cracking in the Primary Reference Data The Accreditation Tester compares the results of the survey carried out by the Contractor using the Equipment over the same sub sections with the Primary Reference Data The Accreditation Tester identifies the 50m sub sections containing a low level of cracking in the Primary Reference Data The Accreditation Tester compares the results of the survey carried out by th
55. as described in paragraphs 3 6 12 through 3 6 14 and assuming that the profile is not considered inadequate as described in paragraphs 3 6 15 through 3 6 20 the nearside cleaned rut depth is calculated as follows Section 3 Transverse Profile Parameters Position of notional straight edge 3 6 22 Within the following paragraph distance L is the length of a notional straight edge typically 2m This length L and minimum distance typically 0 6m should be configurable within the applications software 3 6 23 For each point Dp Nn 1 2 3 etc but excluding unwanted points within Q ascertain whether there is a corresponding point Dp which is to the right of within distance L of and at least distance I from point Dn and such that all points to the right of and within distance L of point Dn lie on or below a line of length L drawn from point Dn and passing thought point Dp 3 6 24 Once a pair of points Dn and Dp has been found that satisfies the conditions the searching process stops see Figure 3 11 Q Qs Q Qs Q Figure 3 11 Criteria for positioning nominal straight edge Figure 3 11 upper demonstrates that there is no point corresponding to point D that satisfies the stated criteria points D2 and D lie above all lines from point D1 Similarly there is no point corresponding to point D2 that satisfies the stated criteria point Dg lies above all lines from point Do
56. asurements made to the left of dmax are not used in subsequent calculations for assessment of transverse profile and are set to 0 zero The re sampled transverse profile with data from the left of dmax set to zero is known as the cleaned transverse profile The position of the road edge within the transverse profile en is a floating point number with a value between 0 0 and half of the measurement width of the transverse profile Where the edge of the road surface cannot be detected within the profile the edge position is given as 0 0 zero Transverse Profile Unevenness The overall process to obtain the transverse profile unevenness can be summarised as shown in Figure 3 5 Remove slope and offset from the cleaned transverse profiles paragraphs 3 5 4 through 3 5 5 Calculate the absolute deviation of the first derivative of the whole of the cleaned and slope offset removed transverse profile data paragraphs 3 5 6 through 3 5 8 Calculate the absolute deviation of the first derivative of the cleaned and slope offset removed transverse profile data in the nearside of the cleaned transverse profile a eS Calculate the absolute deviation of the first derivative of the cleaned and slope offset removed transverse profile data in the offside of the cleaned transverse profile Report these values over the reporting length L Figure 3 5 Obtaining the transverse profile unevenness For definitio
57. ata e g fitting to the Employer s network Before the parameters are calculated checks must be carried out on the validity of the rutting as described in Section 4 2 Checking the rutting data When calculating an average nearside rut depth for a reporting length if any individual measured nearside rut depth is invalid i e outside the permitted range that rut depth is not used in the calculation If more than a defined percentage typically 5 of the individual nearside rut depths within a reporting length are invalid the average nearside rut depth for that reporting length is considered invalid and therefore not reported in the HMDIF file When calculating an average offside rut depth for a reporting length if any individual measured offside rut depth is invalid i e outside the permitted range that rut depth is not used in the calculation If more than a defined percentage typically 5 of the individual offside rut depths within a reporting length are invalid the average offside rut depth for that reporting length is considered invalid and therefore not reported in the HMDIF file Definitions The following definitions apply in the calculation of the average rut depths D longitudinal spacing between successive measured rut depths typically approximately 0 1m L reporting length This should be parameterised the recommended default value is 10m Te total number of measured rut depths pairs
58. aximum invalid points within a calculation length 5 Maximum invalid parameters within a reporting length 50 RMST lower filter mm 0 01 RMST upper filter mm 0 1 Table 5 2 Limits for the calculation of texture profile parameters 6 1 6 1 1 6 2 6 2 1 6 2 2 6 3 6 3 1 Section 6 Cracking Parameters Cracking Parameters General requirements The following parameters will be derived from the cracking data and delivered in the HMDIF file Carriageway cracking intensity Transverse cracking intensity Surface deterioration intensity Left and right wheel track cracking intensity These parameters are calculated from the measured cracking data before any fitting is carried out on the Survey Data e g fitting to the Employer s network Before the parameters are calculated checks must be carried out on the validity of the cracking data as described in Section 6 2 Checking cracking data During the acceptance tests the valid crack type codes will be established It will also be established which of those crack types are to be included in calculation of the parameters e g cracks identified as joints will normally not be included in calculation of cracking intensities Any parameter derived from the cracking data over any reporting length L shall be considered invalid and therefore not output in the HMDIF file if any single crack used to calculate that parameter within
59. cation referencing e eseccceeeeeeseeeeeeeeeeeesseeeeeeeeneenaes 112 8 5 Site tests of road geometry uasvctesa ses cuceths cars edeveadias stevens nceean dans oDebetacgeaaes 113 8 6 Site tests of longitudinal profile 2 0 0 eceececeeeeeeseeeeeeeeeeeesseeeeeeeeneenaas 114 8 7 Site tests of transverse Proll nics ves cucegss cans sdevcaseas esas ecosevinedarseeeetncpeeces 116 8 8 Wheel path US sisii eneret eaa ea aaa 118 8 9 Site tests of texture profile ctu ces ey ca chedaceeeelte cesta cndecheteedeeeia dels 118 8 10 Site tests of Multiple Line Texture eeeeceeeeeeeeeseeceeeeeeeeeneeeeeeeeees 121 8 11 Site tests of cracking intensity measureMent ccceeeeeeeeeeeeeeeees 122 SCANNER User Guide and Specification Volume 5 10 11 12 13 8 12 Site tests of Other Visible Defects 00 eee eeeceeeeeseeceeeeeeeeeseeeeeeeeees 127 S 13 Network testsizsssi noire ceby ca vanstaeconevts a a beret 127 Survey Data Accreditation TeStingi tic dedez scipcostoncwtsves Waeehcepteiay cesugee anedeloteneeees 132 9 1 General TEOUIRGMONS scccse8 stand case ss cebbsrdetuicdey cilonseteednetes intestuebeenewcatts 132 Consistency TESTS rdis erior he reia aa e aeea ketene os aa eieaa 134 10 1 General TEQUINSIMOMIS ic sess che hease seis cabs eeteseneilenseaccaces etescuebeeneeee 134 102 Consistency Tests 2 22c cceae ec tetas eel a tapes 134 10 3 Reporting consistency measurements eee eeeeeeeeeeeeeeeeeeeeeeeeetaeees 135
60. cking parameter Typical value Minimum angle of diagonal feature degrees 17 Maximum angle of diagonal feature degrees 70 Number of steps for definition as a diagonal crack 3 Transverse cracking window length cells 2 Required percentage for definition as transverse crack 20 Surface features A cells 1 Surface features B cells 2 86 Table 6 1 Limits for the calculation of cracking parameters 7 1 7 1 1 Section 8 Data File Formats Data File Formats The Route File Format The definition of a survey route is provided in a single file logically divided into three sections Route header data Survey lanes comprising the route End of Route Reference The file consists of sequential records each containing printable ASCII characters terminated by ASCII Carriage Return and Line Feed characters See Section 7 5 The file contains One record of type R1 1 Table 7 1 followed by One or more of type R2 1 Table 7 2 followed by One record of type R3 1 Table 7 3 The following generic conventions are used within the Format column An indicates a text field of n characters left justified and padded with spaces In indicates an integer numeric field of up to n characters including an optional leading sign or right justified and padded with spaces Fn d indicates a real number field of
61. d The procedure is as follows A gs Ley se bad tl N1 Ax t 0 for i lt d nax y 3 5 7 The absolute deviation of the first derivative of the whole transverse profile is 1 N 1 g 1 N 1 Dev y __ y where a N d rax 1 2 i N d in 1 aay N Number of data points in the re sampled profile i position index on the transverse profile k position index used to calculate average value of first derivative of re sampled profile and y the first derivative calculated at position defined by the index i 3 5 8 The absolute deviation of the first derivative of the transverse profile data minus the slope and offset is calculatedfor the nearside of the profile as 1 H Dev roys gt 1 La H d vax k d nx 1 d max y 39 SCANNER User Guide and Specification Volume 5 3 5 9 3 5 10 3 5 11 3 5 12 3 6 3 6 1 40 where CERN 2 For the offside of the profile the calculation is 1 N 1 Dev N ere FDOS ra N H wor Ds Reporting Devrp DeVrpns and Devrpos are calculated for all valid individual transverse profiles within each reporting length The mean of these up to Te values are then found and defined as DeVrpvavey De Vrpnsiavey and DeVrpos ave The reported value DeVrpyave is the average of Deven for valid profiles within the reporting length Te 1 DeVry ave F gt Dev
62. d in the HMDIF 105 SCANNER User Guide and Specification Volume 5 8 8 1 8 1 1 8 1 2 8 1 3 8 1 4 8 1 5 8 2 8 2 1 8 2 2 8 2 3 8 2 4 106 Accreditation Testing Accreditation Before carrying out any SCANNER accredited surveys the Survey Equipment must have a currently valid Accreditation Certificate awarded following successful Accreditation Testing or subsequent re testing The Employer and or the Auditor may require the Contractor to produce a currently valid Accreditation Certificate for the Survey Equipment at any time The Accreditation Tests may be carried out on any machine and at any time Following the successful completion of the tests the tester issues an Accreditation Certificate for the survey machine to carry out SCANNER accredited surveys for a period of up to 14 months from the first date on which fully acceptable survey data was collected The Auditor may revoke an Accreditation Certificate at any time and require the Contractor to undertake retesting if the Equipment fails to meet the accuracy requirements during SCANNER surveys including Contractor s repeat surveys and Auditor s repeat surveys lf a Contractor makes any significant change to the Equipment after the issue of an Accreditation Certificate the Auditor may require the Equipment to be submitted for an additional Accreditation re test If the Equipment is required to undergo an additional Accreditation re test the Audit
63. developer including acceptance and consistency testing and accreditation It describes the requirements for accreditation of the Equipment It also describes the requirements for consistency testing and for the reporting and delivery of data from SCANNER accredited surveys Volume 1 provides a brief introduction to the requirements for SCANNER surveys and is intended to be read as a free standing document as well as providing an overview of the other four volumes It includes a glossary of terms and a list of the SCANNER parameters as annexes Volume 2 contains advice to Local Authorities about procuring SCANNER surveys under the SCANNER Specification and is to be read in conjunction with the other documents It includes advice on preparing contact documents inviting bids assessing tenders and managing contracts It includes a model contact document as an annex Volume 3 Using SCANNER data explains the background to SCANNER Surveys and gives further guidance on the interpretation of processed SCANNER data It contains advice on receiving and using SCANNER data interpreting the results for local asset management and maintenance producing and understanding performance indicators and reporting NRMCS results Volume 4 SCANNER Survey Data and Quality Assurance defines the technical requirements for the services to be provided by the survey contractor including the Survey Data and the requirements for Quality Assurance procedures to ensure t
64. ditation Testing Date Week beginning RPO azyreooe2nNnO0R2NB8922NRNO0422NVOS22NRNOE2NNQ9242NPH890F2NNMOEX2ZMOBANBOTNYMOHAANHOeBZzNOSHs 002 P0 Li L0z 20 S SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSGSGSGSGSSSSS New machine new manufacturer new operator e g Commence trials 01 01 09 Certificate expires 28 02 10 Period where accreditation trials are completed No SCANNER surveys permitted This period can last as long as necessary Accreditation Approval period Time allowed for analysis of accreditation data by Auditor This lasts a maximum of seven weeks SCANNER surveys can commence once data delivered to Auditor If vehicle fails accreditation the process starts again and completed surveys are invalidated Vehicle accredited No Actions required Certificate lasts 14 months from date of accreditation tests Period where re accreditation testing can be commenced Starts three months before certificate expires Re accreditation Approval period Time allowed for full analysis by Accreditation Tester Vehicle has to be re accredited or SCANNER surveys ceased 8 3 8 3 1 8 3 2 8 3 3 Figure 8 2 Summary accreditation timetable for new SCANNER vehicle Site tests For several of the Site Tests it is necessary for the survey equipment to record the location of the start of each test section to an accuracy better than 1m so that the data provided by the machine developer or Contractor can be accurat
65. dividual RMST values are not included in the summation and Nyai is the number of valid Summed individual RMST values m is the number of measurement lines lying within a distance of 0 3m of the nearside wheel path L has a typical value of 10m giving a typical value of n 100 but should be parameterised L will always be an exact integer multiple of Lrms Mean Middle RMST Mean middle RMST values are calculated by averaging the valid individual RMST values from texture measurement lines lying within a distance of 0 3m inclusive of the nominal line mid way between the nearside and offside wheel paths using the approach described above for the mean nearside RMST Mean Offside RMST Mean offside RMST values are calculated by averaging the valid individual RMST values from texture measurement lines lying within a distance of 0 3m inclusive of the offside wheel path using the approach described above for the mean nearside RMST Note The position offset of the offside wheel path will be determined during the acceptance tests of the Equipment Nearside RMST Variance Nearside RMST Variance values are obtained from the valid individual RMST values from texture measurement lines lying within a distance of 0 3m inclusive of the nearside wheel path 71 SCANNER User Guide and Specification Volume 5 5 5 16 5 5 17 5 5 18 72 1 a ae Variance _ RMST RMST Nval 1 2 J
66. e 10 2 2 Checking the longitudinal profile data ceccceeeeeeeeeeeeeeeeeeeeeeeeeeees 10 2 3 Moving Average Longitudinal Profile Variance ceeeceeeeeeeeeeee eters 12 2 4 Enhanced Longitudinal Profile VarianCe cccccceeeeeseeeeeeeeeeeeeeeeeees 14 2 5 The Bump Measure cies wick cons eee coc deel eh eas chnd seme datas date ated haseeenetede 16 2 6 Typical Values Checks and Limits 0 ecceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeees 18 3 Transverse Profile Parameters lt o ecneceeesssctenes sews usceay otivevabauiietineespieuisenh dude stesbebeteshe 19 3 1 General Requirements tiers J nsazdenie obese scien duceacee cab euuebiaee tateebediadeteetageeve cee 19 3 2 Checking the transverse profile ccesseececeeeeeseeeeeeeeeeesseeeeeeeeneenaes 19 3 3 Definitions Sessan hok Mere A ee Vie et ei lan eae Seba 21 3 4 Cleaning the transverse profiles identifying the road edge 23 3 5 Transverse Profile UneVenneSS c ssccecceeeeeseeeeeeeeeenseeeeeeeeneenaes 37 3 6 Cleaned Rut Depths 455 44 vers eee te te ree eee alee ah as 40 3 7 Edge FOUQNNESS oisic cies edith cess vss cet ee eta ease eta ohana ty 48 3 8 Road COGS Step rerea cadet ied adios vate edocs nade lore 51 3 9 Transverse variante csr veoh a ee yeaah A eles eden lien las 54 3 0 Rims O76 21 6 neon a a a entre ater ar Spree ree eer eer Perr 56 3 11 Typical Values Checks and Limits cccceeeeeseeecceeeeeeseeeeee
67. e 2 A value of 1 for the number of cracks identified and recorded during the survey run implies that the crack detection system was not operational during the survey A value of zero implies that the system was operational but that no cracks were found Section 8 Data File Formats 7 4 11 Record S1 5 Repeated as necessary to define the number of transverse profile points specified in record 1 4 Characters Description Format Value range 1 60 Offsets of up to 10 transverse 10F6 3 9 999 to profile points measured in 9 999 metres from the centre of the survey vehicle negative to the left Offsets to be in order of increasing value Table 7 8 Record 1 5 Survey Header Data repeated as necessary to define the number of transverse profile points specified in record 1 4 Note 1 Where re sampling has been applied the offsets relate to the offsets of the re sampled points 7 4 12 Record S1 6 Repeated as necessary to define the number of multiple line texture measurements points specified in record 1 4 Characters Description Format Value range 1 5 Offsets of up to 10 multiple line 10F6 3 9 999 to texture values RMST 9 999 measured in metres from the centre of the survey vehicle negative to the left Offsets to be in order of increasing value Table 7 9 Record 1 5 Survey Header Data repeated as necessary to define the number of multip
68. e Contractor using the Equipment over the same sub sections with the Primary Reference Data The tests for measuring Cracking Intensity will be passed only if all of the following requirements are met for each survey run The Equipment shows a high level of cracking over at least 65 of the 50m sub sections that the Primary Reference Data shows to have high level of cracking The Equipment shows a low level of cracking over at least 85 of the 50m sub sections that the Primary Reference Data shows to have a low level of cracking The overall level of agreement between the level of cracking recorded by the Equipment and the Primary Reference Data for each 50m sub section for low moderate and high levels of cracking combined is 75 8 11 14 8 11 15 8 11 16 8 11 17 8 11 18 Section 8 Accreditation Testing As a test of repeatability the Accreditation Tester applies the above requirements separately to the Cracking Intensity recorded in each of the survey runs carried by the Contractor If the Equipment is able to meet all of the above requirements section 8 11 13 the Accreditation Tester accredits the Equipment to carry out SCANNER accredited surveys If the Survey Equipment is unable to meet all of the above requirements section 8 11 13 the Accreditation Tester assists the Contractor to investigate the performance of the Equipment in the measurement of Cracking Intensity to ascertain the reasons for the failure to
69. e Reference Method Site tests of road geometry The Accreditation Tester selects a test site and divides it into a number of Sections marking the start and end of each section with a reflective post The Accreditation Tester surveys the test site for Gradient Cross fall and Radius of Curvature using the Reference Method s given in Table 8 1 The geometry of the site may vary with cross fall gradient and curvature lying in the full range specified in Volume 4 The Contractor defines a survey route appropriate for the survey of the test site surveys the test site at a range of speeds as required by the Accreditation Tester and delivers the SCANNER RCD and the SCANNER HMDIF files from the test site to the Accreditation Tester The Accreditation Tester subtracts the gradient and cross fall recorded in the SCANNER RCD files provided by the Contractor from the gradient and cross fall measured with the Reference Method expressed over 5m lengths For the radius of curvature measurements the Accreditation Tester will assess the accuracy of the equipment in terms of the curvature defined as 1 radius of curvature and therefore will subtract the curvature obtained from the Scanner RCD and Scanner HMDIF from the reference curvature The test is passed if all the following criteria are met e 95 of the differences between the measured Gradient and the Reference Gradient fall within 1 5 gradient or 10 of the Reference G
70. e accreditation testing timetable 137 SCANNER User Guide and Specification Volume 5 12 12 1 12 1 1 12 1 2 12 1 3 12 1 4 138 Annex 1 Identifying False Cracks Removal of false positives from the edge of survey data The following procedures may be applied to identify and remove false positive cracked grid cells at the edge of the survey width The method requires that a crack grid has already been obtained as described in section 6 4 To define edge cracking the nearside and offside outer edges of the survey width are defined as edge regions Each edge region is made up of 1 or more columns of grid cells The identification of excessive cracking at the road edge is undertaken by evaluating the percentage cracking within each column over a defined length If the cracking exceeds a defined threshold all the cracked cells within that column are removed from the crack grid A further test evaluates the percentage cracking over the whole of each edge region over a defined length If the cracking exceeds a defined threshold all the cracked cells within that region are removed from the crack grid The classification of false positives within the edges should be carried out using the following configurable parameters The number of columns of cells in each edge region default 2 The first column of the nearside region is the outermost column in the nearside the first column of the offside region is the outermost colum
71. e and Specification Volume 5 3 6 17 3 6 18 3 6 19 3 6 20 3 6 21 44 Figure 3 10 Example of inadequate profile for cleaned rut depth calculation In the general case when calculating the nearside cleaned rut depth if the slope from D to D exceeds s downwards the profile should be considered inadequate and the individual cleaned rut depth should not be calculated Similarly when calculating the offside cleaned rut depth if the slope from Dz to Diz exceeds s downwards the profile should be considered inadequate and the individual cleaned rut depth should not be calculated The value for A is obtained by dividing 100mm by the transverse spacing of the re sampled data points rounded down to the nearest integer Where this indicates a value of A 0 A 1 should be used For 25 mm re sampled profile point spacing this gives A 4 When calculating the nearside cleaned rut depth if point D4 has been eliminated as defined in paragraphs 3 6 12 through 3 6 14 the check for an inadequately measured profile should not be carried out Similarly when calculating the offside cleaned rut depth if point Dz has been eliminated as defined in paragraphs 3 6 12 through 3 6 14 the check for an inadequately measured profile should not be carried out In such cases the measured profile is always considered as adequate Calculation of nearside cleaned rut depth Having eliminated any unwanted points
72. e maximum second derivative in the right third of the profile between position pan and pyn 1 inclusive with value higher than Q If such a maximum is not found Q is used for the ratio calculation described in 3 4 19 Note that paws is the index for re sampled position 2 N 3 rounded up to the nearest integer and pa 1 is position index N 1 Calculate the ratio between maximum second derivatives as per 3 4 19 If the ratio is lower than or equal to r defined in 3 4 19 If Pa 400 t set pa 400 t 1 Calculate slopeo as slope 5 yl 7 Ensuring t and y are expressed in the same units where j is the index for the re sampled point corresponding to the second measurement laser position such that x 2x1 and x _ lt x1 the edge position Pebp S calculated as If slopeo lt 0 11 Pebp the smaller of pa and pp If the ratio is greater than r the edge position Pebp is the greater of pa and Pc 31 SCANNER User Guide and Specification Volume 5 3 4 26 3 4 27 34 39 32 If the second derivative at pa is positive Look for the maximum second derivative with value higher than Q occurring over the length N 3 from p2 to pna where pns is the index for re sampled position N 3 rounded down to the nearest integer Define pa as the position at which the maximum second derivative with value higher than Q from p2 to pws occurs If such a maximum is not found pa 0 and Q
73. e number of profile points corresponding to a moving average length e g 3m and 10m is calculated as MovingAverageLength l rounded to the nearest odd integer exact even numbers rounded up where interval between profile point readings e g For 3m and 10m moving average lengths with a readings interval of exactly 0 1m the number of points would be 31 and 101 respectively The number of profile points corresponding to the length L over which LPV is to be reported e g 10m is calculated as rounded to the nearest odd integer exact even numbers rounded up where interval between profile point readings e g For 3m and 10m moving average lengths with a readings interval of exactly 0 1m the number of points would be 31 and 101 respectively For each point k on the survey run a moving average is calculated as ie 1 j itm 1 j i m where Yj Profile amplitude at point j 2 3 5 2 3 6 2 3 7 2 3 8 Section 2 Longitudinal profile parameters m 1 m 7 k ranges from 2 to 2 and M total number of readings in the run For each point k on the survey run a profile amplitude deviation from its corresponding moving average is calculated as d Y Ve where Y profile amplitude at point k The moving average Longitudinal Profile variance LPV over each reporting length L starting at point i is calculated as 6 i4 J 1 Lev S a
74. e profile data points are defined as starting from 0 which is the first measurement point at the extreme nearside left of the profile y individual recorded original transverse profile normalised transverse profile See paragraph 3 4 5 or smoothed transverse profile see paragraph 3 4 8 Xi measurement point position q number of data points in the measured transverse profile h transverse sampling interval in the measured transverse profile data h x X The value of h may vary between measurement positions across the profile y re sampled individual transverse profile A position of the re sampled point N number of data points in the re sampled profile t transverse sampling interval in the re sampled transverse profile data t Note This should be parameterised the recommended default value is 25mm qL number of points to include in moving average calculations from the left of current point in y qR number of points to include in moving average calculations from the right of current point in y D longitudinal spacing between successive transverse profiles typically approximately 0 1m Lave Averaging Length Note This should be parameterised the recommended default value is 1m 21 SCANNER User Guide and Specification Volume 5 Table 3 1 3 3 3 22 Tave number of transverse profiles in an averagin
75. e profiles have been measured over the edge of the road surface Profiles that do not measure past the edge of the road surface are indicated by a located road edge position value en of zero The value en is the road edge location found for each profile For each reporting length Count the number of valid transverse profiles within the reporting length which have a road edge position en gt 0 the valid coverage U Calculate the value U as U 100 u Te Typical Values Checks and Limits Typical values to be confirmed during acceptance tests for the checks and limits to be placed on the transverse profile data are given in Table 3 3 Typical Value Rut depth kerb value mm 20 Rut depth slope value 15 Max of inadequate profiles within an averaging length 25 Length of notional straight edge for rut depth m 2 Minimum distance between peaks for rut depth m 0 6 Table 3 3 Typical values for the calculation of transverse profile parameters 4 1 4 1 1 4 2 4 2 1 4 2 2 4 3 4 3 1 Section 4 Rut Parameters Rut Parameters General requirements The following parameters will be derived from the rutting data and delivered in the HMDIF file Average nearside rut depth over each reporting length Average offside rut depth over each reporting length These parameters are calculated from the measured rutting data before any fitting is carried out on the Survey D
76. e the Accreditation Tester endorses the Accreditation Certificate with the results of the comparison The comparison with the Secondary Reference Data may show significant differences between the Cracking Intensities reported by the Equipment or show deficiencies in the capability of the Equipment In these cases the Accreditation Tester will require the Contractor to explain the reasons for these differences and will give the Contractor an opportunity to make improvements to the Equipment Differences or deficiencies that remain at the conclusion of the Accreditation Tests may result in the Accreditation Tester specifying restrictions on the use of the Equipment or the refusal to issue an Accreditation Certificate Site tests of Other Visible Defects Currently there is no requirement to measure or to report other visible defects as part of the SCANNER specification Network tests Providing that the Accreditation Tester accepts the performance of the Survey Equipment in the Site Tests the performance of the Contractor and the Survey Equipment is further examined in the Network Tests The Network Tests assess the overall operational capability of the Contractor and the Survey Equipment in carrying out surveys under conditions typical of those to be encountered on the local road network They test Route planning Survey procedures Efficiency of operation of the Survey Equipment Alignment of the surveyed route with the
77. e variability measure assesses the evenness of the texture across the width of pavement The measurement can be summarised as follows Obtain the dataset of individual RMST values for each measurement line as described in paragraphs 5 5 2 through 5 5 10 5 5 19 5 5 20 5 5 21 Section 5 Texture Profile Parameters Calculate the 5th and 95th percentiles and variance of the valid individual RMST values within this dataset over texture variability reporting lengths of 10m paragraphs 5 5 19 through 5 5 21 Percentile The percentile value is defined as The ith valid individual RMST value after the valid individual RMST values from all measurement lines in the texture variability reporting length L have been sorted into increasing order where iis equal to N x 100 rounded to the nearest integer exact 0 5 values rounded up N is the number of valid individual RMST values from all measurement lines in the texture variability reporting length L x is the percentile value required For example for a system recording texture profiles in 10 measurement lines an individual RMST calculation length LRMS of 0 1m and a texture variability reporting length L of 10m N will have a maximum value of 10 10 0 1 1000 If there are 996 valid individual RMST values within a particular texture variability reporting length the 5th percentile will result in a value of i 996 5 100 49 8
78. ed in the SCANNER RCD 7 4 Data Format 7 4 1 Data is provided in a single file logically divided into eight sections one for each of the data types described in the previous section of this document Survey header data Location data Geometric data Longitudinal profile and speed data Transverse profile data Wheelpath rutting data Texture data Multiple Line Texture Data Crack data 7 4 2 The file consists of sequential records each containing printable ASCII characters terminated by ASCII Carriage Return and Line Feed characters As defined in the following sections the file contains One record of type S1 1 followed by One record of type S1 2 followed by One record of type S1 3 followed by One record of type S1 4 followed by None one or more records of type S1 5 followed by None one or more records of type S2 1 followed by None one or more records of type S3 1 followed by None one or more records of type S4 1 followed by None one or more records of type S5 1 followed by None one or more records of type S6 1 followed by None one or more records of type S7 1 followed by None one or more records of type S8 1 followed by None one or more records of type S9 1 92 7 4 3 7 4 4 7 4 5 7 4 6 7 4 7 Section 8 Data File Formats Where a record type has the capacity for more than one value se
79. eeneeees 56 4 R t Paame S a a ee tacks ete ate 57 4 1 General requirements oraiiio eiie deaa an iea iiaeie a 57 4 2 Checking the rutting Cates seeders saves ete vensceten segs elanaedige star aiadeetan dieses 57 4 3 Definitions vis eor Gin ee seoeinepca san ea sealed utes seagate Gen ened stunted ats 57 4 4 Pverage Rut Depts sisisi nene e ae cas e e e a aae aaia aaa e i 58 4 5 Typical Values Checks and Limits 0 ecceeeeeeeeeeeeeeeeeeeeeeeeneeeeeeeeees 59 5 Texture Profile Parameters ici isccecececeenaicencdetocts wie ndneheedynettnclaeenededadines 60 5 1 General requirements sseeeeeeeeeeeeee testere r ncuedeayaheiatnantenien thats 60 5 2 Checking the texture data 1c pcchcseetistenctietecah vic dingieleceae he 60 Survey Parameters and Accreditation 5 3 Nearside Sensor Measured Texture Depth SMTD eeeeee 61 5 4 Nearside Mean Profile Depth MPD cscceccecceeeeeeeeeeeeeeeeeeeees 62 5 5 Multiple Line Root Mean Square Texture Depth RMST 67 5 6 Typical Values Checks and Limits eeceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee 74 Cracking Parameters 2 22 sicscad hates aie achiwectetehdascnnes sapetva les tole k ake Scee the stel capeatents 75 6 1 General requirements asssess ches cco ies cercatensne duces Dedes sheds See enbeceetahemsedtenss 75 6 2 Checking cracking data scccctccepecstsulnet cscs feaeott cane apes iteand eae tees edeeca et 75 6 3 Cleaning the crack
80. efined as Zj Tja d t d j j l 2 5 3 The Central Difference Method is applied to all points to obtain the set of values Pj 2 5 4 The Central Difference Method is applied once more to Pj to give the set of values P where Pj is defined as p Pia Pia 4 h a d d ja ja 2 Gin 4 Gj z jal dj Sy dj d d i2 a d d d d Xd 51 d d d j j 2 2 5 5 The datasets P and P are then reduced as follows Calculate the maximum absolute value of Pj over each 1m length to give a dataset F containing values for each 1m length Calculate the maximum absolute value of Pj over each 1m length to give a dataset F containing values for each 1m length Applying thresholds 2 5 6 Generate a further intermediate dataset Bi with data spaced at 1m intervals 2 5 7 Any 1m length where F 278 6 mm m and F 2487 4 mm m2 is considered to contain a bump Note that these values should be parameterised in software to enable future revisions to the thresholds 16 2 5 8 2 5 9 Section 2 Longitudinal profile parameters The value of B for this length is assigned a value of 1 Remaining values of B are assigned a value of 0 The Bump Measure is reported over 10m lengths Note that 10m is the default length but should be parameterised in software Any 10m reporting length containing a non zero value of B will be reported as a Bump
81. ely aligned with the Reference Data To enable this level of accuracy to be achieved the Accreditation Tester places markers at the test section start and end points adjacent to the nearside of the traffic lane being surveyed These markers take the form of posts approximately 0 75m tall The face of the posts aligned longitudinally with the traffic lane are covered with a retro reflective material of dimensions approximately 0 65m by 0 1m The survey equipment must record the location of these posts placed at the test Section start and end points to an accuracy of better than 1m over the range of speeds under which the survey equipment would normally be operated The Accreditation Tester provides the Contractor with a plan describing the test sites and the survey procedures to be applied e g survey speeds on those sites at least 5 working days before the commencement of the tests For the Site Tests the Contractor Surveys the test sites as instructed by the Accreditation Tester in the plan provided before the tests Where reflective posts are placed at the Section Start and End Points records the location of the posts marking the Section Start and End Points to an accuracy of better than 1m using suitable equipment installed on the survey equipment 109 SCANNER User Guide and Specification Volume 5 Processes the Survey Data from the test site to generate SCANNER RCD and SCANNER HMDIF files Note W
82. ence Methods to be used in the Accreditation Tests 111 SCANNER User Guide and Specification Volume 5 8 4 8 4 1 112 Site tests of location referencing The Accreditation Tester selects a test site and divides it into a number of Sections marking the start and end of each section with a reflective post The site may contain both straight and curved Sections The site may contain Sections having levels of GPS signal availability in terms of the length of the Section over which the GPS signal is available ranging from less than 10 availability of GPS signal to greater than 90 availability The Contractor defines a survey route appropriate for the survey of the test site surveys the test site at a range of speeds as required by the Accreditation Tester and delivers the SCANNER RCD and the SCANNER HMDIF file from the test site to the Accreditation Tester The Accreditation Tester compares the lengths of the Sections recorded in the SCANNER RCD and SCANNER HMDIF files provided by the Contractor with the lengths of the Sections measured by the Reference Method The Accreditation Tester compares the National Grid Co ordinates and the Altitudes recorded in the SCANNER RCD and SCANNER HMDIF files provided by the Contractor with National Grid Co ordinates and the Altitude recorded for these Sections using the Reference Method The test is passed if all the following criteria are met 95 of the measured Section lengt
83. ence maximum Rut Depth in each Wheelpath fall within 1 5mm 95 of the differences between the measured maximum Rut Depths in each Wheelpath and the Reference maximum Rut Depth in each Wheelpath fall within 3 0mm All of the differences between the measured maximum Rut Depths in each Wheelpath and the Reference maximum Rut Depth in each Wheelpath are less than 10 0mm or 50 of the magnitude of the Reference Rut Depth whichever is the greater Site tests of texture profile The Accreditation Tester selects a test site consisting of a single Section for the assessment of the measurement of raw texture profile marking the start and end of the Section with a reflective post 8 9 2 8 9 3 8 9 5 8 9 6 Section 8 Accreditation Testing The Section contains features of a known Texture Profile characterised using conventional measurement methods These measured shapes are referred to as the Reference Profile for the assessment of Texture Profile measurement The Accreditation Tester selects a further test site and divides it into a number of Sections for the assessment of the measurement of Sensor Measured Texture Depth SMTD and Mean Profile Depth MPD marking the start and end of each section with a reflective post The site may contain both straight and curved Sections but will not contain any extremes of geometry The Accreditation Tester measures the texture profile of the site usin
84. eporting length 6 8 Wheel track Cracking Intensity 6 8 1 The wheel track cracking intensity is obtained by first examining the position and length of each crack to determine whether the crack is a wheel track crack as demonstrated in Figure 6 6 Centreline of survey Left wheel track crack Right wheel track crack Not a wheel track crack Not a wheel track crack 0 8m 0 6m 0 6m 0 8m __ q_p gt 4 gt e gt Overall survey width Figure 6 6 Classification of wheel track cracks 6 8 2 The determination of wheel track cracks is carried out using the following configurable parameters Offset to the right edge of the left wheel track typically 0 6m The width of the left wheel track typically 0 8m 82 6 8 3 Section 6 Cracking Parameters The offset to the left edge of the right wheel track typically 0 6m The width of the right wheel track typically 0 8m The width of the grid cells for the left wheel track grid typically 0 8m The width of grid cells for the right wheel track grid typically 0 8m The length of the grid cells for the left wheel track grid typically 0 2m The length of the grid cells for the right wheel track grid typically 0 2m The percentage of the length of the crack required to be within the wheel track for the crack to be classified as a wheel track crack typically 80 Maximum absolute angle of a crack for it
85. er supervises and controls the tests The Contractor attends the accreditation retests and carries out any surveys or data processing required by the Accreditation Tester at its own cost During the re testing the Survey Equipment is driven and operated by drivers and operators named in the Contractor s quality system The Accreditation re testing assesses the accuracy of the Survey Equipment in the measurement of each survey parameter and is carried out on a site or sites selected by the Accreditation Tester The accreditation retesting follows the same general procedure as the Accreditation Tests described in Section 8 However it is unlikely that tests of acceleration and deceleration described in section 8 6 will be carried out during re testing of the measurement of longitudinal profile unless the Accreditation Tester specifically requires these tests The tests will normally take same form as the Accreditation Tests but reduced in extent and duration including site tests as described in Sections 8 3 to 8 11 a short network test as described in Section 8 13 on a route located conveniently near the site tests and survey data acceptance tests as described in Section 9 The Contractor delivers the survey data obtained in the re testing to the accreditation tester as SCANNER RCD and SCANNER HMDIF files for all test sites used in the re testing within 8 working days following the date when the surveys for the re tests were carried o
86. essed in the same units as A and the trigonometric functions are defined such that the arguments are in radians 5 5 5 5 5 6 5 5 8 Section 5 Texture Profile Parameters The coefficients blp are then normalised so that if the coefficients were plotted against i the total area under the graph would equal one i e the area under the filter window is equal to one Hence blp blip n for i m 2 m 2 1 m 2 mi2 Where ee gt bip i m 2 There are m 1 high pass coefficients bhpi These coefficients define a high pass filter which attenuates frequencies below the frequency limit f To calculate the high pass coefficients the method described above for calculating the low pass coefficients is applied but where the frequency limit f is now equal to the lower frequency limit of the filter fL This generates a new set of coefficients termed blp Following the normalisation of the coefficients as described above the following transformation is performed on the coefficients bhp lt blip for i m 2 m 2 1 1 and for i 1 m 2 i e for i 0 bhp 1 blip fori 0 The coefficients of the band pass filter are obtained by combining the low pass and high pass coefficients The m 1 values of bp obtained through the convolution of blp and bhp are given by min 2 i4 bp bhp bip m m j max i 2 j i fori m 2
87. exactly 0 1m the 100th reading at chainage 10m is deemed to lie within the 0 10m reporting length Note also that the first reading is deemed to be at a small value of chainage I e g 0 1m not at zero At the start and end of the survey there will be lengths over which it is not possible to calculate moving averages e g for a 3m moving average it is not possible to calculate a value until 1 5m into the survey Reporting lengths that include these are considered invalid and therefore not reported in the HMDIF file although this should not affect the data if there has been a run in before the start of the first section and a run out after the end of the last section Enhanced Longitudinal Profile Variance The calculation of 3m and 10m Enhanced Longitudinal Profile Variance can be summarised as follows The raw longitudinal profile is filtered using a high pass filter that attenuates frequencies below 3m and 10m as appropriate The Enhanced Longitudinal Profile Variance is calculated from the filtered profile over the reporting length Filtering The filter is defined by a set of m plus one coefficients m s where fL A A is the interval between profile points approximately 0 1m 1 f is expressed in the same units as A For the calculation of 3m enhanced profile variance f is 0 3333m For the calculation of 10m enhanced profile variance f is 0 1m R is the Filter Order which
88. f survey A11 Valid date dd mmm yyyy e g 31 dec 2006 26 30 Time at the start of the survey A5 00 00 to hh mm 24 hour clock e g 23 59 09 35 93 SCANNER User Guide and Specification Volume 5 7 4 8 7 4 9 94 Characters Description Format Value range 31 41 Date at the end of survey A11 Valid date dd mmm yyyy e g 31 dec 2006 42 46 Time at the end of the survey A5 00 00 to hh mm 24 hour clock e g 23 59 13 43 Table 7 4 Record S1 1 Single Record Survey Header Data Record S1 2 Single Record Characters Description Format Value range 1 80 Survey identifier A80 Table 7 5 Record S1 2 Single Record Survey Header Data Record 1 3 Single Record Characters Description Format Value range 1 11 x co ordinate at the start of the F11 3 0 000 to survey data measured in metres 9999999 999 12 22 y co ordinate at the start of the F11 3 0 000 to survey data measured in metres 9999999 999 23 31 z co ordinate at the start of the F9 3 9999 999 to survey data measured in metres 9999 999 32 32 Start of survey co ordinate status I1 0to2 33 43 Chainage at the end of the F11 3 0 000 to survey data measured in metres 9999999 999 44 54 x co ordinate at the end of the F11 3 0 000 to survey data measured in metres 9999999 999 55 65 y co ordinate at the end of the F1
89. file inadequately measured profiles shall be excluded from the rut depth calculation for the side evaluated as inadequate invalid profiles as defined in paragraph 3 2 1 shall be excluded from the rut depth calculation for both sides Determine the cleaned rut depth below an appropriately positioned 2m straight edge Figure 3 7 Determining individual cleaned rut depth Calculating individual cleaned rut depths 3 6 7 The slope and offset suppressed cleaned valid transverse profile is defined as covering a lane of width of W The points relate to relative distance with each such distance being labelled D4 to Dz in accordance with the corresponding transverse profile point where D4 is the left most point and Dz is the right most point in the direction of travel Increasing D Datum q of W __ 5 a Figure 3 8 Transverse profile points for calculating rut depth 3 6 8 The lane width is subdivided into four parts Q4 being that from the left most edge to a pre defined percentage q typically 25 of distance W from the left most edge Q is that from the right most edge to q of W from the right most edge Q2 and Q equally subdivide the remaining width between Q and Q4 3 6 9 Points are reported vertically relative to an artificial horizontal datum with increasing value being upward 42 3 6 10 3 6 11 3 6 12 3 6 13 3 6 14 3 6 15 3 6 16 Section 3
90. file and the Reference Profile fall within the ranges given in column A of Table 8 2 95 of the cross correlation coefficients equal or exceed the values given in column B of Table 8 2 65 of the errors between Enhanced and Moving average Longitudinal Profile Variances calculated from the measured profile and the Enhanced and Moving average Longitudinal Profile Variances calculated from Reference Profile respectively fall within the ranges given in column C of Table 8 2 95 of the errors between the Enhanced and Moving average Longitudinal Profile Variances calculated from the measured profile and the Enhanced and Moving average Longitudinal Profile Variances calculated from Reference Profile respectively fall within the ranges given in column D of Table 8 2 The Accreditation Tester assesses accuracy separately for surveys carried out at constant speed and surveys carried out under conditions of deceleration The Accreditation Tester compares the performance of the Equipment at each level of deceleration with the accuracy requirements given in Table 8 2 for the surveys carried out under conditions of deceleration 115 SCANNER User Guide and Specification Volume 5 The Accreditation Tester records the level of deceleration at which in its opinion the Equipment fails to provide measurements to an acceptable level of accuracy when compared with the accuracy requirements given in Table 8 2 This defines the limit of dece
91. ft of the road edge removed ee Correlate each individual re sampled transverse profile with the corresponding best transverse profile to locate the edge of road in the individual re sampled transverse profile Figure 3 2 Cleaning the transverse profiles identifying the road edge The following paragraphs summarise in further detail the steps for locating the road edge and removing non road features from the transverse profile Normalise each transverse profile by determining the lowest profile height and subtracting that value from all the profile heights within that profile paragraph 3 4 5 If the horizontal spacing between any adjacent profile points is less than t normally 25mm the noise in each transverse profile is removed by applying a moving average in the transverse direction paragraphs 3 4 7 through 3 4 8 Each transverse profile is re sampled using a cubic spline paragraphs 3 4 9 through 3 4 13 to provide transverse profiles with points spaced transversely at a distance t typically 25mm A longitudinal averaging length Lave is defined from which the number of profiles per averaging length Tave is determined Successive Tave transverse profiles are used to calculate the average profile for each averaging length within a reporting length L paragraphs 3 4 14 through 3 4 16 The position of the edge of the road esp is determined in the average profile producing a be
92. g length Tave Lave D rounded down to the nearest integer y Averaged best re sampled transverse profile in length Lave y First derivative of the averaged best re sampled transverse profile y Second derivative of the averaged best re sampled transverse profile L reporting length which must be an exact integer multiple of ave Note This should be parameterised the recommended default value is 10m Tc total number of transverse profiles in reporting length L Tc Tave L Lave n index for the transverse profiles within the survey or reporting length as applicable en road edge position in millimetres from the nearside end of the measured transverse profile Definitions for Transverse Profile Parameters Where the averaging length Lave and reporting length L are not exact multiples of the longitudinal spacing between successive transverse profiles D there will be more transverse profiles than required within some reporting lengths e g With an averaging length of 1m a reporting length of 10m and a spacing of 0 09925m Tave will be calculated as 1 0 09925 10 075567 rounded down to 10 and Tc will be calculated as 10 10 1 100 however the number of transverse profiles lying within each 10m reporting length will be as shown in Table 3 2 3 3 4 3 3 4 3 4 3 4 1 3 4 2 3 4 3 Section 3 Transverse Profile Parameters
93. g the Reference Method given in Table 8 1 for the measurement of SMTD and MPD The Contractor defines a survey route appropriate for the survey of the test site carries out one or more surveys of the test site as required by the Accreditation Tester and delivers the SCANNER RCD and the SCANNER HMDIF files to the Accreditation Tester The Accreditation Tester assesses the measurement of texture Profile by the Equipment over the test site and provided in the SCANNER RCD as follows The texture profile recorded in the SCANNER RCD provided from the test site for the assessment of the measurement of raw texture profile is subtracted from the Reference Profile to obtain the differences between the texture profile and the reference profile The SMTD and MPD are calculated over 10m lengths from the texture profiles recorded in the SCANNER RCD provided from the test site for the assessment of the measurement of SMTD and MPD These values will then be subtracted from the SMTD and MPD calculated from measurements of texture Profile previously made on the selected lengths using the Reference Method s to obtain the differences between the measured SMTD MPD and the Reference SMTD MPD The tests for texture profile measurement will be passed if 95 of the differences between the measured Texture Profile and the Reference Profile from the test site for the assessment of the measurement of raw texture profile fall within
94. hat the values of the parameters e g variance provided in the HMDIF files by the Contractor are the same as the reference parameters obtained by the Accreditation Tester using their own systems Tests the SCANNER HMDIF file to ensure that it complies with the requirements of the UKPMS specification in all respects Checks a sample of SCANNER HMDIF files to ensure that the format is consistent with the current version of the HMDIF specification and the current version of the UKPMS Rules and Parameters May ask any or all of the organisations that supply UKPMS accredited Pavement Management Systems to check the Contractors SCANNER HMDIF files to ensure that the files can be loaded into their Pavement Management Systems Notifies the Contractor if the SCANNER HMDIF files cannot be loaded or if any differences are found between the format of the SCANNER HMDIF file and the current version of the HMDIF If required by the Accreditation Tester the Contractor explains any differences and amends the systems until the parameters match the reference parameters On completion of these tests the Accreditation Tester approves the system for the delivery of SCANNER HMDIF files The Contractor ensures that Section 9 Survey Data Accreditation Testing All processing of SCANNER survey data is carried out using the approved HMDIF generation software No changes are made to the HMDIF generation software without approval from the
95. he Services are consistent and reliable It also includes the specifications for audit processes monitoring calibration and requirements for repeat surveys SCANNER User Guide and Specification Volume 5 1 1 1 1 1 1 3 1 3 1 Introduction Scope and Content This volume 5 of the User Guide for SCANNER surveys on local roads Technical requirements for SCANNER Survey Parameters and Accreditation Provides a detailed specification of the technical requirements of the parameters to be derived from the Survey Data Describes the requirements for the reporting and delivery of data from SCANNER accredited surveys Describes the requirements for testing the Equipment to become accredited by site and network tests Also describes the requirements for consistency testing Terms are defined in a Glossary in Volume 1 of this User Guide Introduction to SCANNER surveys Derived Parameters and Data Files The survey contractor uses accredited Equipment to carry out the surveys This volume 5 defines how the Survey Data are to be analysed to produce the derived parameters Sections 2 to 7 provide definitions of the derived parameters The definitions also specify methods for handling the Survey Data when obtaining the derived parameters for example how to deal with invalid data The survey contractor provides the Survey Data and derived parameters in specific file formats One format Raw Condition Data R
96. here reflective posts are placed at the Section Start and End Points and are recorded by the survey equipment it should not normally be necessary to align the Survey Data with the planned survey route before generating the SCANNER RCD and SCANNER HMDIF files However where it is found necessary to carry out alignment of the Survey Data with the planned survey route the Contractor ensures that the elapsed distances of the section change points recorded in the location records of BOTH the SCANNER RCD and SCANNER HMDIF files are the aligned post fitted distances 8 3 4 The Accreditation Tester uses a number of Reference Methods to assess the accuracy of the Equipment in the Site Tests these are summarised in Table 8 1 110 Section 8 Accreditation Testing Parameter Parameter measure Values to be compared Reference Method for Site Tests type with Reference Location Distance Travelled Measured lengths of Calibrated Measuring wheel and Referencing Sections Steel Tape National Grid Co ordinates of Section start points National Grid Co ordinates of Section start points Static GPS combined with an Optical Survey National Grid Co ordinates of positions of moving vehicle National Grid Co ordinates of positions of moving vehicle Static GPS combined with an Optical Survey Geometry Gradient Gradient Rod and level Crossfall Crossfall Rod and level Radius
97. hs fall within 1m or 0 1 whichever is larger of the Section lengths measured using the Reference Method 95 of the measured National Grid Co ordinates are within 2m of the National Grid Co ordinates measured using the Reference Method for those Sections having better than 70 availability of the signal used by the equipment for the calculation of National Grid Co ordinates 95 of the measured National Grid Co ordinates are within 10m of the National Grid Co ordinates measured using the Reference Method for those Sections having less than 70 availability of the signal used by the equipment for the calculation of National Grid Co ordinates e All of the measured National Grid Co ordinates are within 50m of the National Grid Co ordinates measured using the Reference Method e 95 of the measured Altitudes are within 5m of the Altitudes measured using the Reference Method for those Sections having better than 70 availability of the signal used by the equipment for the calculation of National Grid Co ordinates 8 5 8 5 1 8 5 2 8 5 3 8 5 4 8 5 5 8 5 6 Section 8 Accreditation Testing 95 of the measured Altitudes are within 10m of the Altitudes measured using the Reference Method for those Sections having less than 70 availability of the signal used by the equipment for the calculation of National Grid Co ordinates e All of the measured Altitudes are within 50m of the Altitudes measured using th
98. ight third of the profile The ratio is calculated as the absolute value of the larger of these two second derivative maxima divided by the smaller value This ratio is then compared to a threshold r in order to determine how the road edge location is selected for each profile Note A value for the threshold of r 5 is recommended but this value should be parameterised The edge is therefore located as follows The labels Psubscript are used in the following procedure to refer to positions across the average profile such that the position Psubscript corresponds to the re sampled transverse position Xp and averaged profile height Yp uiscrip Where the subscript is a number n then pn n where n is the n 1 re sampled position across the profile Define the leftmost point in the average profile as position po Check the sign of the first derivative the sign of y at pe the seventh point in the average profile Find the first position in the interval pe Pawe 1 where N 6 1 is rounded down to an integer value where the first derivative y has the opposite sign to that found in pe then let the preceding point be pa If the first derivative does not change sign in the interval then For Ye 0 find the minimum value of y in the range p7 to p N 6 1 If that minimum value is less than Ye Pa is set to the location of that minimum value If the minimum value is NOT less than Ye Pa is set to p N 6 2
99. inage interval between F12 9 0 000000000 transverse profiles measured in to metres see note 1 below 99 999999999 54 55 Number of points within each 12 0 to 99 transverse profile see note 2 below 56 67 Chainage interval between F12 9 0 000000000 wheelpath rutting values to 95 SCANNER User Guide and Specification Volume 5 measured in metres see note 1 99 999999999 below 68 73 Offset of texture profile points F6 3 9 999 to measured in metres from the 9 999 centre of the survey vehicle negative to the left 74 85 Chainage interval between F12 9 0 000000000 texture profile points measured to in metres see note 1 below 99 999999999 86 97 Chainage interval between F12 9 0 000000000 multiple line texture profile to values measured in metres 99 999999999 see note 1 below 98 99 Number of points within each 12 0 to 99 multiple line texture measurement 100 104 Number of cracks identified and I5 0 to 99999 recorded during the survey run 3 see note 3 below Table 7 7 Record 1 4 Single record Survey Header Data Note 1 A value of zero for a chainage interval implies that that particular item of data will not be included in the data file Note 2 Where the measurement system collects more that 99 points per transverse profile the profile may need to be re sampled prior to delivery as RCD This shall be agreed with the Auditor Not
100. ine SCANNER accredited surveys The timescales involved in Accreditation Re testing are outlined below and an example accreditation timetable for a SCANNER survey vehicle is given in Figure 11 1 Testing Period starts three months before certificate expires ALL accreditation test sites to be surveyed during this phase SCANNER surveys are permitted Re Testing Accreditation Approval Period maximum length four weeks The test data from ALL the test sites must be delivered to the Accreditation Tester four weeks before certificate expires Accreditation If successful SCANNER Certificate awarded Following the successful completion of an annual re test the tester issues a SCANNER Accreditation Certificate for a further period of up to 12 months Date Week beginning Period where re accreditation testing can be commenced Starts three months before certifcate expires RE Accreditation Approval period Time allowed for analysis of accreditation data by Auditor This lasts a maximum of four weeks SCANNER surveys can commence once data delivered to Auditor If vehicle fails accreditation the process starts again and completed surveys are invalidated Vehicle accredited No Actions required Certificate lasts 12 months from date of re accreditation tests Vehicle has to be re accredited or SCANNER surveys ceased E g Certificate expires 31 12 08 Certificate expires 31 12 09 Figure 11 1 Example r
101. ine texture values and spacing of values Note 1 An invalid RMST value must be output as 99999 101 SCANNER User Guide and Specification Volume 5 Crack data 7 4 20 Record S9 1 Repeated as necessary to provide data for the number of cracks defined in record S1 4 three cracks per record Characters Description Format Value range 1 11 Chainage measured in metres F11 3 0 000 to 9999999 999 12 17 Offset measured in metres from F6 3 9 999 to the centre of the survey vehicle 9 999 negative to the left 18 22 Length measured in metres F5 3 0 000 to 9 999 23 25 Angle measured in degrees 13 90 to 90 from the direction of travel negative anticlockwise 26 27 Type code A2 1 to 99 28 54 As Cols 1 27 for next crack 55 81 As Cols 1 27 for next crack Table 7 17 Record S9 1 Repeated as necessary to provide data for the number of cracks 102 defined in record S1 4 three cracks per record Section 8 Data File Formats 7 5 SCANNER RCD Character Set 7 5 1 The ASCII printable characters given in Table 7 18 may be included within SCANNER data Char Dec Char Dec Char Dec Char Dec Char Dec Char Dec Code Code Code Code Code Code Space 32 0 48 64 P 80 96 p 112 33 1 49 A 65 Q 81 a 97 q 113 i 34 2 50 B 66 R 82 b 98 r 114 35 3 51 C 67 S 83 c 99
102. ing data e cc 2eccsssesteleasseattieneaei de arene eee tees 75 6 4 Obtaining the carriageway cracking grid sssessseeeeeeseernresererrrrreseene 76 6 5 Carriageway Cracking Intensity 0 eeeeeeeeeeeeeeeeeeeeeeeeeeeeenaeeeeeeeeneaees 79 6 6 Transverse Cracking Intensity cccessseceeeeeeeeeseeeeeeeeeteeeseneeeeeeenes 79 6 7 Surface Deterioration Intensity ceessecceeeeeeseeeeeeeeeeeenseeeeeeeeneeneaees 80 6 8 Wheel track Cracking Intensity cceceeeeeeeeeee tees eeeeeeeeeeeeeeeeneeeeereeee 82 6 9 Typical Values Checks and Limits ecceceeeeeeeseeeeeeeeeeeeeeeeeeeeeeeees 84 Deiter Fil Formats gst ere a o a a a E EE E E 87 7 1 The Route File Formats prarepa e E ea 87 7 2 The Fitted Route File senceres i aiio ioii 89 7 3 SCANNER RGD File Format va seesten eveiscetn eed nena tea are des eee 89 7 4 Data Ss da ake Smee eta a e E E E Ea 92 7 5 SCANNER RCD Character Set snnneeeeeeeeeeeeeeerrreeesrrerrresrrrrreereeee 103 7 6 SCANNER Format Definitions scc ies cecciytiss ceo ieeehscte decete wis tcete ames 104 7 7 SCANNER HMDIF Data Format cece cecceeeeeeeeneeeeeeeeeeeeeaeeeeeeeenaes 105 Accreditation TOSTHNG sie sccstvesciesmucthcdesuale ae Saute eked beste ete odes ENA 106 8 1 PAC CVC ONAN i as ea eo a aslo eA ts ceed 106 8 2 General requirements ccs ete easels cle a eles Vente idee cele tals 106 8 3 SOUT CS FS ec sea a eee A tae lade a el eae 109 8 4 Site tests of lo
103. ion Tester The Accreditation Tester assesses the measurement of Multiple Line Texture RMST by the Equipment over the test site by assessing the Nearside Middle and Offside Mean RMST provided in the SCANNER HMDIF file as follows The measured Nearside Middle and Offside Mean RMST measurements will be subtracted from reference Nearside Middle and Offside Mean RMST measurements The tests for texture profile measurement will be passed if e 95 of the differences between the measured and the Reference Nearside Middle and Offside Mean RMST respectively fall within 0 25mm e All of the differences between the measured and the Reference Nearside Middle and Offside Mean RMST respectively fall within the range 0 75mm 121 SCANNER User Guide and Specification Volume 5 8 11 8 11 1 8 11 2 8 11 3 8 11 4 8 11 5 122 Site tests of cracking intensity measurement The Accreditation Tester selects a number of test sites and divides them into one or more Sections marking the start and end of each Section with a reflective post The sites may cover a broad range of crack intensities pavement constructions including fully flexible rigid and composite surface types surface texture crack widths and crack orientations as may be found on UK local road networks There are two sources of reference data for the Accreditation Tests of the measurement of cracking shown in Table 8 1 termed the Primary
104. is used for the ratio calculation described in 3 4 19 The minimum second derivative with value lower than Q is looked for to the right of pa between position pa and pns Let the position at which the minimum second derivative with value lower than Q between position pg and pws Occurs be pe If such a minimum is not found Pe O Find the maximum second derivative in the right third of the profile between position paws and pn 1 inclusive with value higher than Q If such a maximum is not found Q is used for the ratio calculation described in 3 4 19 Note that paws is the index for re sampled position 2 N 3 rounded up to the nearest integer and pvn 1 is position index N 1 Calculate the ratio between maximum second derivatives as per 3 4 19 If the ratio is lower than or equal to r defined in 3 4 19 If pa 400 t set pa 400 t 1 The edge position Pepp is calculated as If Pa lt 400 t Pebp Pa If Pa gt 400 t Pebp the smaller of pa and pa If the ratio is greater than r Pebp is defined as the greater of pa and pe If the second derivative at pa is zero Pebp 0 If the calculated edge position egp is not the position Po then the slopes between adjacent measurement laser positions are examined as a further check for removal of the verge Where the re sampled profile does not 3 4 29 3 4 30 3 4 31 Section 3 Transverse Profile Parameters contain a
105. isation of the measured profile Normalisation may include for example the removal of the Crossfall from the Reference and measured profiles The test will be passed if 95 of the differences between the measured Transverse Profile points and the Reference Profile points fall within 1 5mm The Accreditation Tester also selects a number of test sites on the local road network and divides them into a number of Sections The Accreditation Tester provides the Contractor with a map showing the 8 7 6 8 7 7 8 7 8 8 7 9 8 7 10 Section 8 Accreditation Testing location of the sites and the description of each Section start and end point on each site The sites may cover a broad range of rut depths and other transverse features The Accreditation Tester measures the transverse profile present on the test sites using the Reference Method given in Table 8 1 The Contractor defines a survey route appropriate for the survey of each of the test sites carries out one or more surveys of the test sites as required by the Accreditation Tester and delivers the SCANNER RCD to the Accreditation Tester The Accreditation Tester visually examines the transverse profiles recorded in the SCANNER ROD in particular over lengths where the Contractor is expected to have surveyed over the road edge The Accreditation Tester calculates the Cleaned Rut depths from the transverse profile provided within the SCANNER RCD and reports
106. itation timetable is outlined below and an example accreditation timetable for anew SCANNER survey vehicle is given in Figure 8 2 Testing Period no set timescale ALL accreditation test sites to be surveyed during this phase NO SCANNER surveys are permitted Accreditation Approval Period maximum length seven weeks The test data from at least the site level tests must be delivered to the Accreditation Tester before this stage can commence SCANNER surveys are then permitted but these MUST be agreed with the Accreditation Tester There then follows a three week period where the Accreditation Tester processes the site level test data and the Survey Contractor must deliver all remaining test data network routes and crack sites There then follows a four week period where the Accreditation Tester completes all data analysis 107 SCANNER User Guide and Specification Volume 5 8 2 9 e Accreditation SCANNER Certificate awarded for 14 months from the date the site level tests commenced To ensure continuous accreditation the Vehicle may commence re accreditation testing 12 months after certificate started Following the successful completion of an annual re test the tester issues a SCANNER Accreditation Certificate for a further period of up to 12 months Certificate Annex Certificate No 9999 SCN SCANNER2 Issue 2 SCANNER CERTIFICATE 3 Survey Parameter Pass Fail Certificate No 9999 SCN SCANNER2 Issue 1 Grid C
107. itive as illustrated in Figure 12 2 The search then recommences from the cell to the right of the cell identified in step a If step a commenced from a cell at the Section 12 Identifying False Cracks right hand side of the crack grid then proceed to the first cell in the left hand side of the next row in the crack grid Optional additional search An additional search of all cells within a 1m circumference of the starting point of each feature could improve the identification but is subject to further investigation NE direction Figure 12 1 The sequence of grid cells to be searched starting at a crack identified in the shaded square 141 SCANNER User Guide and Specification Volume 5 Centre Line H 1 4m L 10 cracked grid squares 2 0 W 2 2m S number of steps 6 A 32 All criteria are satisfied hence reclassify as false positive Figure 12 2 Example of the reclassification of a traffic sensor or other diagonal feature 142 13 13 1 13 1 1 13 1 2 13 1 3 Section 13 Other Visible Defects Annex 2 Other Visible Defects General requirements Research by Scott Wilson and the University of Nottingham identified the potential of combining high quality images of the road surface with sophisticated image recognition software to identify visible defects that might indicate road surface wear or deterioration Scott Wilson Pavement Engineering Ltd Department for Transport SCANNER resea
108. ker The term 10 is included to convert the result from m to mm Where the reporting length is not an exact multiple of the reading interval there will be more readings than required within some reporting lengths e g With a reporting length of 10m and a reading interval of 0 09925m J will be calculated as 10 0 09925 100 75567 rounded down to 100 however the number of readings lying within each 10m reporting length will be as shown in Table 2 1 Reporting Length Number of Readings 0 10 100 10 20 101 20 30 101 30 40 101 40 50 100 Etc Table 2 1 Reporting length versus number of readings In such situations the extra readings at the end of the reporting lengths are used in calculating moving averages Y however a profile amplitude deviation need not be calculated for those points and is not included in the calculation of moving average Longitudinal Profile variance LPV The speed values associated with the extra readings also are not included in the speed checks described in paragraphs 2 2 6 and 2 2 7 but are included in the calculation of average speeds as described in paragraph 2 2 9 13 SCANNER User Guide and Specification Volume 5 2 3 9 2 3 10 2 4 2 4 1 2 4 3 14 When a reading falls exactly on the boundary between two reporting lengths it is deemed to lie within the former of those lengths E g With a reporting length of 10m and a reading interval of
109. label of the node at the end of the previous section and co ordinates if known Other data items may be provided if known or may be blank zero as appropriate Note 2 The XSP code should be that appropriate to the direction of survey not the direction of section referencing Thus when surveying Lane 1 in either direction on two way section the XSP Code should be CL1 88 7 2 7 2 1 7 3 7 3 1 Section 8 Data File Formats Note 3 The section description is for information only and would normally include the road number and descriptions of the start and end of the section in the direction of survey Whilst this is good practice and is strongly recommended it is not something that can be taken for granted as there is considerable variation in the standard of description and definition of local road networks End of Route Reference Record R3 1 Single record as defined in Table 7 3 Characters Description Format Value range 1 20 End Node label i e node at the A20 end of the last section within the route 21 31 End Node x co ordinate if F11 3 0 000 to known 9999999 999 32 42 End Node y co ordinate if F11 3 0 000 to known 9999999 999 Table 7 3 Record R3 1 End of Route Reference The Fitted Route File The Contractor provides the Fitted Route File in the same format as the Route File SCANNER RCD File Format Overview Survey
110. le variance calculated along these paths Located road edge en Inner boundary of 0 5m edge strip e Points where variance value is used by this method Figure 3 13 Calculation of the edge roughness defining the area of interest 3 7 8 For a reporting length of L metres let Yin represent a particular transverse profile height measurement height in mm where i is the number of the point in the transverse profile ranging from 0 being the leftmost point to q 1 and n is the number of the transverse profile in the reporting length ranging from 0 to Te 1 49 SCANNER User Guide and Specification Volume 5 3 7 10 3 7 11 50 e g fora 10m reporting length L with 20 point q transverse profiles longitudinally spaced at 0 09925m intervals D Te will be calculated as 100 and there will be 2000 transverse profile height measurements labelled yo 0 y19 0 yo 1 y19 1 Yo 99 y19 99 The number of transverse profiles used in each MALPV calculation is 2M 1 where D gt 0 12m 0 09m lt D lt 0 12m 0 07m lt D lt 0 09m int 0 3 D D lt 0 07m For each transverse profile n where n 2 M and n lt T M Determine whether any of the transverse profiles in the range n M to n M are invalid If so MALPV values are not calculated for points within the current transverse profile i e the next three stages should be skipped for the current transverse profi
111. le and both an and B are set to zero a and Bn as defined below Determine the range of points within the current transverse profile that lie within the edge strip i e at offsets between en and n 500mm including any that lie exactly at en or en 500mm The number of transverse profiles so determined for profile n is defined as an For each point i lying within the edge strip calculate the MALPV y i n in units of mm defined as jJ n M l y i n y n TE ET a determine the number of MALPV values greater than Viim For profile n this number is defined as Bn For the reporting length the number of transverse profile points within the edge strip for which a MALPV has been calculated is denoted as A where the number of transverse profile points within the edge strip with MALPYV values greater than Vim is denoted as B where 3 8 3 8 1 3 8 2 Section 3 Transverse Profile Parameters n T M 1 B gt 8 edge roughness is reported as R where R B A Road edge step The road edge step is derived for each reporting length L from the valid measured transverse profiles within that reporting length that have an edge position en greater than zero Note that it is the original measured transverse profiles prior to normalising smoothing re sampling and cleaning that are used when calculating the road edge step The algorithm delivers Lsi1 Small step do
112. le line texture values specified in record 1 4 Location data 7 4 13 Record S2 1 Repeated for each node as defined in record 1 4 Characters Description Format Value range 1 20 Node label A20 21 31 Chainage measured in metres F11 3 0 000 to 9999999 999 Table 7 10 Record 2 1 repeated for each node as defined in record 1 4 97 SCANNER User Guide and Specification Volume 5 7 4 14 98 Geometric data Record S3 1 Repeated as necessary to provide number of measurements as defined by length of survey and spacing of values Characters Description Format Value range 1 11 x co ordinate F11 3 0 000 to 9999999 999 12 22 y co ordinate F11 3 0 000 to 9999999 999 23 31 z co ordinate F9 3 9999 999 to 9999 999 32 32 Co ordinate status Rec S1 3 11 0to2 Note 1 33 37 Gradient measured as a F5 1 99 9 to percentage relative to horizontal 99 9 positive implying upwards travelling in the direction of the survey see Note 1 38 42 Crossfall as a percentage F5 1 99 9 to relative to horizontal positive 99 9 implying right higher than left in the direction of the survey see Note 2 below 43 50 Radius of curvature measured in F8 2 9999 99 to metres positive implying a left 9999 99 hand curve travelling in the direction of the survey see Note 3 below 51 Deviation flag D indicates that A1 D or
113. leration under which the Equipment provides acceptable data A B C D Wavelength Profile Profile Cross Variance Variance m differences Correlation Error 65 Error 95 o Coefficient 95 3m 2 00 0 75 0 30 0 60 10m 4 00 0 85 0 35 0 70 Note For 3m and 10m Longitudinal Profile Variance the tolerances are in terms of the either differences or the fractional errors between the Longitudinal Profile Variances calculated from the measured profile and the Longitudinal Profile Variances calculated from the Reference Profile as defined in Volume 4 Table 8 2 Accuracy requirements for the Site Tests of longitudinal profile 8 7 8 7 1 8 7 2 8 7 3 8 7 4 8 7 5 116 Site tests of transverse profile The Accreditation Tester provides one or more lengths laid out with features of a known Transverse Profile The shapes of these features will be characterised using the Reference Methods given in Table 8 1 These measurements will be referred to as the Reference Profiles for the assessment of Transverse Profile measurement The contractor measures the Transverse Profile of these features at a range of speeds The Accreditation Tester compares the measured Transverse Profiles with the Reference Profile as follows The differences between the Reference Profile and the measured profile will be calculated by subtraction of the Reference Profile from the measured profile following any required normal
114. longitudinal spacing between successive measured rut depths of exactly 0 1m the 100 pair of measured rut depths at chainage 10m is deemed to lie within the 0 10m reporting length 58 4 4 3 4 5 4 5 1 Section 4 Rut Parameters For each wheel path the average rut depth for a reporting length is calculated by averaging the up to Te individual rut depths for that wheel path including zero rut depths but excluding invalid rut depths 1 n T Average nearsiderut depth CS gt Rut n CvalL J n l where any invalid nearside rut depth is excluded from the summation and Tevait is the number of Summed valid nearside rut depths n T Average offside rut depth Rut n CvalR J n l where any invalid offside rut depth is excluded from the summation and Tevair is the number of Summed valid offside rut depths Typical Values Checks and Limits Typical values to be confirmed during acceptance tests for the checks and limits to be placed on the rutting data are given in Table 4 2 Typical Value Maximum percentage of invalid measured 5 ruts in an reporting length Table 4 2 Limits for the calculation of rutting parameters 59 SCANNER User Guide and Specification Volume 5 5 5 1 5 1 1 5 1 2 60 Texture Profile Parameters General requirements The following parameters are derived from the texture profile and delivered in the RCD file or HMDIF file
115. lues are all calculated for each profile as follows Section 3 Transverse Profile Parameters j 6 D 1 2 arai T 7 L ni ol 6 H d 1 where 1 H S y H d aax 1 2 1 S R y N H 1 i H 1 and 2 3 9 8 With the cleaned profile values contained within Y in units of mm the output profile variance values will be in the units of mm Calculating the transverse variance difference measure for the reporting length 3 9 9 Calculate the mean average of the up to Te values of T for valid transverse profiles within the reporting length L 1 n Tc 1 Tive gt T n Tovar n 0 where any invalid profile is excluded from the summation and Tevai is the number of summed valid profiles 3 9 10 Calculate the mean average of the up to Te values of Tr for valid transverse profiles within the reporting length L 55 SCANNER User Guide and Specification Volume 5 3 9 11 3 10 3 10 1 3 10 2 3 10 3 3 11 3 11 1 56 1 n T 1 lez DA fs n Teva n 0 where any invalid profile is excluded from the summation and Tevai is the number of summed valid profiles The average difference between the two halves of the profile for the reporting length can then be calculated as TpiFFave Trave Trave This is the value reported from the method Coverage The coverage value U is evaluated for each reporting length L This value indicates the percentage of the length where th
116. lues for the checks limits and to be placed on the cracking parameters data are given in Table 6 1 Section 6 Cracking Parameters Cracking parameter Typical value Width of cells whole carriageway cracking m 0 2 Cells across grid whole carriageway cracking 16 Offset to centre of whole carriageway grid m 0 Length of cells whole carriageway cracking m 0 2 Offset to right edge of left wheel track m 0 6 Width of left wheel track m 0 8 Offset to left edge of right wheel track m 0 6 Width of right wheel track m 0 8 Required percentage of crack in wheel track 80 Maximum absolute angle for wheel track crack degrees 90 Offset to right edge of left wheel track grid m 0 6 Width of cells left wheel track grid m 0 8 Cells across grid left wheel track grid 1 Length of cells left wheel track grid m 0 2 Offset to left edge of right wheel track grid m 0 6 Width of cells right wheel track grid m 0 8 Cells across grid right wheel track cracking 1 Length of cells right wheel track cracking m 0 2 Columns in each edge region 2 Length of edge region in cells 20 Required percentage for definition as false edge cracking by 50 column Required percentage for definition as false edge cracking by 50 region Minimum length to be a diagonal crack m 1 4 85 SCANNER User Guide and Specification Volume 5 Cra
117. maximum value of d Calculation of offside cleaned rut depth The offside cleaned rut depth Rutosc is calculated in the same way as but a mirror image of the nearside cleaned rut depth i e working from the right edge of the transverse profile Average cleaned rut depths For each wheel path the average cleaned rut depth over the prescribed length L e g 10m is calculated by averaging the individual cleaned rut depths for that wheel path including zero cleaned rut depths but excluding inadequate or invalid transverse profiles as follows To ae Rut NSC if Tog gt 9 Cval n l Rut yscave 0 if Toa 9 Rut ysccave Te F Dy Rutosc if Toya gt 9O Cval n l Rutosc aey 9 if Te Rut OSC ave T 0 val where Tevai is the number of Summed valid profiles 47 SCANNER User Guide and Specification Volume 5 3 7 3 7 1 3 7 5 3 7 6 48 Edge roughness The edge roughness is derived for each reporting length L from valid measured transverse profiles within that reporting length Note that the original measured transverse profiles prior to normalising smoothing re sampling and cleaning are used when calculating edge roughness For definitions relating to this algorithm see section 3 3 However the following further definition applies Vim Edge roughness longitudinal profile variance threshold A typical value for Viim is 3mm however this should be parameterised
118. measured profile by subtracting the filtered Reference Profile from the filtered measured profile 8 6 9 8 6 10 8 6 11 Section 8 Accreditation Testing If required the Accreditation Tester normalises the measured profiles and calculates the cross correlation coefficient between the filtered Reference Profile and the filtered measured profile The measurement of Longitudinal Profile Variance measured by the survey equipment over the test site and provided in the SCANNER RCD is assessed as follows The Accreditation Tester calculates both the 3m and 10m Enhanced and Moving Average Longitudinal Profile Variances from the Longitudinal Profiles measured by the survey equipment over 10m lengths The Accreditation Tester subtracts these values from the 3m and 10m Enhanced and Moving Average Longitudinal Profile Variances calculated from measurements of Longitudinal Profile previously made on the selected lengths using the Reference Method s to obtain the differences between the measured and the Reference Enhanced and Moving Average Longitudinal Profile Variances The Accreditation Tester calculates fractional errors by dividing the differences by the 3m and 10m Enhanced and Moving Average Longitudinal Profile Variances calculated from the Reference Profile The tests for longitudinal profile are passed for the surveys carried out at constant speed if 95 of the differences between the measured Longitudinal Pro
119. measurement error for each survey machine individually The Tester reports the individual results to the relevant Contractor and to the relevant national government responsible for statistical monitoring and performance indicators The Accreditation Tester determines the overall single industry wide measurement of bias determined from the consistency tests The Accreditation Tester reports the overall performance of all SCANNER accredited survey machines as the basis for calculating the confidence limits for an individual authority s BVPI results 135 SCANNER User Guide and Specification Volume 5 11 11 1 11 1 1 11 1 2 11 1 3 11 1 4 11 1 5 11 1 6 11 1 7 11 1 8 11 1 9 11 1 10 136 Accreditation Re testing General requirements At intervals of one year the Contractor submits the Survey Equipment for retesting to demonstrate that it still meets the SCANNER specification requirements under rigorously controlled test conditions In the event of a failure to achieve the survey requirements set out in the quality assurance and audit regime Survey Equipment may be required to undergo additional Accreditation re testing The requirements for Quality Assurance and Audit for SCANNER accredited surveys are set out in Volume 4 of the SCANNER User Guide In the event of additional accreditation re testing the standards defined in this volume 5 for accreditation testing and re testing apply The Accreditation Test
120. meet the required standards This investigation may include for example Allowing the Contractor to re process the Survey Data in view of the performance achieved during the first tests of the survey data Reviewing performance in terms of surface type Reviewing performance in terms of surface texture Reviewing performance in terms of surface features such as road furniture joints etc The Contractor and the Accreditation Tester may repeat the assessment of the Equipment taking into account the results of the further investigations to determine whether the Equipment is suitable for carrying out surveys on parts of the local road network with limitations or restrictions If the Equipment is acceptable but with restrictions on the areas of the local road network for which it is acceptable then The Accreditation Tester endorses any Accreditation Certificate to identify the limitations of the Survey Equipment and the restrictions on its use to provide SCANNER accredited surveys e The Contractor removes all cracks identified on such areas from the Survey Data before delivering either the SCANNER RCD or the SCANNER HMDIF files to any Employer The lengths for which the Contractor is unable to provide acceptable measurements of Cracking Intensity do not contribute to the coverage requirements for the measurement of Cracking Intensity If required the Contractor agrees a procedure with any Employer for pro
121. n Consultancy and TRL Limited Extensive revisions to the 2006 7 specification were undertaken by Halcrow leading to a draft revised specification for the 2007 8 Scanner survey year This 2007 8 specification has been reviewed and further revised by TRL to produce the specification for Scanner surveys carried out from April 2009 Throughout the development of the TTS and Scanner specifications considerable assistance and support has been given by members of the SCANNER Implementation Group including local authority representatives by TRL Limited by the UKPMS Development Support Consultant Chris Britton Consultancy by SCANNER survey contractors by Halcrow by Nick Lamb Consultancy Ltd and by UKPMS developers This volume is mainly based on work carried out by Dr Alex Wright and his team at TRL Limited which is gratefully acknowledged SCANNER User Guide and Specification Volume 5 Contents 1 PETE OC IG HON ss eee a a apa seme enerencegueuee dpe A Javeeu suena E a 8 1 1 Scope and COMPCMB etiscecasicnias tun asinncelvi obey alec s dedien casataaied ten badd sieds ceases 8 1 2 Derived Parameters and Data Files eecsessseeeeeesseceeeeeeeesseeeeeeeeenes 8 1 3 Accreditation and Consistency saseseiseecebicccesiuacasectasuaecteines Uden baes ew eepeeeeds 8 2 Longitudinal Profile Parameters jccccciteks ete ctapiieedicivis eet ieee ade ae cipher 10 2 1 General TEquirementSsscccserst tease teshcset scious oe ndaag sie endeared aakoee
122. n in the offside For example for a 3 3m survey width and 0 2m grid cells there are 17 columns For 2 column regions the nearside region would be columns 1 and 2 the offside region would be columns 16 and 17 The number of grid cells defining the length of each edge region default 20 The percentage area of each column required to reclassify all cracks within the column as false positive default 50 The percentage of the total edge region area required to reclassify all cracks within edge region area as false positive default 50 The identification of false positives within the edges should be determined using the following rules note that the method is applied to the nearside and offside edges separately Commencing at the start of the survey data evaluate the total area of cracking within each edge column over the defined length For each column if the percentage of cracked grid cells exceeds the specified percentage all cracks within the column are reclassified as false positive 12 1 5 12 2 12 2 1 12 2 2 Section 12 Identifying False Cracks Evaluate the total area of cracking in each edge region If the percentage of cracked grid cells in the region exceeds the specified percentage all cracks within this region are reclassified as false positive and can be removed during the calculation of carriageway cracking intensity The process is repeated starting from the next grid cell e g
123. ngth is invalid Only valid individual parameters are included in the calculation of the mean percentile or variance Nearside Sensor Measured Texture Depth SMTD Nearside Sensor Measured Texture Depth is calculated from the texture profile recorded in the nearside wheel track as described in the following paragraphs The number of texture profile points corresponding to a standard deviation length of D typically 0 3m is calculated as j l rounded to the nearest odd integer exact even numbers rounded up where l interval in metres between texture profile point readings typically approximately 0 001m e g For a standard deviation length of 0 3m and a readings interval of exactly 0 001m the number of points would be 301 The number of standard deviation lengths corresponding to the reporting length L over which SMTD is to be averaged typically 10m is calculated as L nx rounded down to the nearest integer e g For 10m average lengths a standard deviation length of 0 3m and a readings interval of exactly 0 001m the number of standard deviation lengths would be 33 An individual SMTD value over a length D is calculated as 2 n n 2 an p a we i l SMTD aan n n n 2 54 n 1 y 125 x2y i i l c A n 4 where 61 SCANNER User Guide and Specification Volume 5 5 3 5 5 3 6 5 4 5 4 1 62 Xi nominal scaled distance at point i within the length D
124. ns relating to this algorithm see section 3 3 The outputs from the algorithm are 37 SCANNER User Guide and Specification Volume 5 38 The value of the absolute deviation of the first derivative of transverse profile data for the whole transverse profile DeVrpvave The value of the absolute deviation of the first derivative of the transverse profile in the nearside of the profile DeVepnscave The value of the absolute deviation of the first derivative of the transverse profile in the offside of the profile DeVeposvave Note the algorithms are applied to every valid individual re sampled transverse profile and are concerned only with points to the right of en Section 3 Transverse Profile Parameters Slope and offset suppression 3 5 4 Slope and offset suppression is done by determining the best fitting straight line through the re sampled profile based on a least squares fit and subtracting that line from the profile 3 5 5 Given the total number of valid data points N N dmax in the re sampled profile and the re sampled profile the best fitting straight line through the profile is defined by N l N l 12 i 6 N DY i d max i d nax slope N N D N D N 1 N 1 2 2N 1 gt 6 J i offset i d max i d max N N 1 First derivative of transverse profile 3 5 6 The first derivative of the transverse profile data minus the slope and offset is calculate
125. nsverse profile To do this each valid transverse profile used to obtain the best transverse profile is compared with the best transverse profile to determine the amount by which the individual transverse profile must be shifted to obtain optimum alignment with the best transverse profile This shift is used to calculate the road edge position in each individual valid transverse profile en This shift is found using cross correlation theory The approach used is described within the following paragraphs 3 4 26 to 3 4 32 33 SCANNER User Guide and Specification Volume 5 3 4 32 3 4 33 3 4 34 34 Note A sample implementation for this part of the algorithm can be supplied by TRL Limited For any two profiles a correlation curve is defined This correlation curve is defined formally by calculating at a given lag d the product of two profiles being compared The value R of the correlation curve for any given lag value d is given as Rd gt 9 45 where y is the best transverse profile y is the re sampled transverse profile Index i varies from 0 to N 1 d represents the lag value which indicates the number of re sampled data points by which the best transverse profile must be shifted in order to provide the optimal correlation with any individual re sampled transverse profile Note The above definition for calculating the correlation curve is
126. o XY R R 1 X Y m c Y mX X R R 1 X i R i R Where KY y hey X a i R i R Pe F g Sy C nA Se eS aAA R R 1 i R R R 1 i R 3 8 5 This best fit line is then extrapolated from Xo to X 1 3 8 6 The difference between the measured profile height at xj and the height predicted by the best fit line is defined as sj 3 8 7 For each point in the transverse profile from position Xo to xy i e from the nearside of the transverse profile to the point immediately to the left of the edge position calculate the values So to Sy measured relative to the datum line Y defined above Si yi Y Xi 52 3 8 8 3 8 9 3 8 10 3 8 11 3 8 12 Section 3 Transverse Profile Parameters A positive step is defined as one where the measured profile height is greater than the profile height predicted by the best fit line A negative step is defined as one where the measured profile height is less than the profile height predicted by the best fit line Record the largest positive value step up Smax So in Figure 3 14 and largest negative value step down Smin S2 in Figure 3 14 from the dataset obtained in paragraph 3 8 7 If no positive step values of Si occur Smax 0 if no negative step values of Si occur Smin O As paragraph 3 8 8 evaluates the maximum and minimum values in the region to the left of the edge point the value Smax is
127. o ordinates PASS aiins Road Geometry This is to certify that metry Gradient PASS SCANNER1i E Sres Registration number AB 123 XYZ urvature PASS Longitudinal Profile Measured using the GM method in both the nearside and offside wheelpaths Deceleration limits 3m variance 3m s 10m variance 2m s Minimum survey speed for the reporting of longitudinal profile data Operated by Survey Contractor Ltd Road Name Town City Post Code has undertaken SCANNER testing at TRL Crowthorne House Nine Mile Ride Wekingham RG40 3GA under the aned nearside amp offside rut depths edge supegmmion of Taig td ded amp tj is prove ct anrggx to cogmect SC within I x met the accreditation requirements outlined in z the UK roads board specification SCANNER Delivery of texture SCANNER parameters Nearside z middle and offside RMST and TMST variance 5 and surveys for local roads March 2007 and this 95 percentile and variance of texture variability qualifies the system to be used for the Cracking pee SiN toned Indicators Using auto sensitivity for surface type and recognising the limitations of the system which is not accredited Signed for and on behalf of TRL Limited for concrete surfaces Ab Other Date of Issue 24 December 2007 Date of expiry 25 December 2008 108 Figure 8 1 Illustrative example of a SCANNER Accreditation Certificate Section 8 Accre
128. ollowing configurable parameters The length over which the surface deterioration feature intensities are to be calculated and reported typically 10m which shall be an integer multiple of the length of each grid cell 80 Section 6 Cracking Parameters Size of Area A cells Figure 6 5 Size of Area B cells Figure 6 5 6 7 3 The calculation of surface deterioration features intensity is carried out using the following definitions Area A All grid cells within the surrounding circumference of the selected cracked grid cell Area B All grid cells between the surrounding circumference and 0 4m circumference of the selected cracked grid cell Cracked grid cell Area A Area B PRI rin re aana O Figure 6 5 Classification of surface deterioration features 6 7 4 The calculation of surface deterioration features intensity is carried out using the following approach Starting at the start of the survey data assess each grid cell containing a crack e If for this cracked grid cell no cracked grid cell exists in area A and no greater than one cracked grid cell exists in area B then classify the assessed cracked cell as containing surface deterioration 81 SCANNER User Guide and Specification Volume 5 6 7 5 The surface deterioration features intensity is expressed as the total percentage area of grid cells defined as containing surface deterioration features for each r
129. or may also require the Equipment to be submitted for an additional Consistency re test The Accreditation Tester may also assess the competence of drivers and operatives as part of the Accreditation Testing and the annual re testing General requirements The Accreditation Tests assess the capability of the Equipment in the measurement and reporting of the parameters specified in the following sections The accuracy of the equipment in the measurement of each parameter is assessed separately so that the equipment may be judged as acceptable or not as applicable in the measurement of each parameter individually The machine developer or Contractor attends the Accreditation Tests and carries out any surveys or data processing required by the Accreditation Tester at its own cost The Equipment is driven and operated by drivers and operators named in the Contractor s quality system The Accreditation Tester supervises and controls the tests The Accreditation Testing is carried out as site tests network tests and survey data acceptance tests 8 2 5 8 2 6 8 2 7 8 2 8 Section 8 Accreditation Testing In the site tests the parameters measured by the survey equipment are compared with those measured by the Reference Methods on test sections located on sites selected by the Accreditation Tester The network tests assess the operational capabilities of the survey equipment when carrying out surveys under normal opera
130. ormally space digit with a total of n characters Note In some instances where only positive values are permitted the width of a field may preclude the inclusion of a sign character This is intentional 7 6 4 mlin means m consecutive fields of format In More formally In 7 6 5 Fn d means a real number field of up to n characters including the decimal point and an optional leading sign with d digits after the decimal point right justified and padded with spaces More formally space 4 digit digit with a total of n characters Note In some instances where only positive values are permitted the width of a field may preclude the inclusion of a sign character This is intentional 104 Section 8 Data File Formats 7 6 6 mFn d means m consecutive fields of format Fn d More formally Fn d 7 7 SCANNER HMDIF Data Format 7 7 1 The SCANNER HMDIF file takes the format of a Highways Maintenance Data Interchange Format HMDIF file 7 7 2 The SCANNER HMDIF file should be produced in accordance with the latest released version of UKPMS Document 71 SCANNER HMDIF Specification available on the UKPMS Web Site www ukpms com 7 7 3 The HMDIF format does not have the ability to accommodate invalid data and therefore lengths containing invalid values should not be reporte
131. owing data are provided Set of n transverse profile points n is the number of points within each transverse profile as defined in the survey header data Wheelpath rutting data For each interval as defined in the survey header data the following data are provided Rut depth in nearside wheelpath Rut depth in offside wheelpath Texture data For each interval as defined in the survey header data the following data are provided Single texture profile point Multiple Line Texture data For each interval as defined in the survey header data the following data are provided Set of n multiple line texture RMST values n is the number of points within each multiple line texture measurement as defined in the survey header data Crack data For each crack identified during the survey run the following data are provided Chainage Offset e Length e Angle Type code Invalid data There may be instances where it is not possible to produce a valid value for a parameter due to for example limitations of the equipment For each parameter where this may occur a specific invalid 91 SCANNER User Guide and Specification Volume 5 value is reserved and must be output in such circumstances The invalid value for each parameter is defined in Section 7 4 Note there is no invalid value for cracking Invalid crack measurements should not be report
132. planned route and accuracy of locating Section start points Accuracy of the SCANNER RCD and SCANNER HMDIF files Coverage obtained by the Survey Equipment The Accreditation Tester selects one or more test sites consisting of several Sections The sites include road types that are typical of the local road network in terms of construction condition and traffic levels The test sites may include Flexible and rigid constructions Urban and rural roads Single and dual carriageway roads e Traffic light controlled junctions 127 SCANNER User Guide and Specification Volume 5 8 13 4 8 13 5 8 13 6 8 13 7 128 Slip roads Roundabouts and A wide range of typical road geometries The Accreditation Tester obtains Reference Data on the test sites using the Highways Agency Road Research Information System HARRIS The Accreditation Tester processes Survey Data provided by the HARRIS survey vehicle to provide the following Reference Data for the Network Tests for each Section within the test site reported relative to elapsed chainage within Section as appropriate The OSGR co ordinates of the Section Start Points Reported at 10m intervals i The OSGR co ordinates reported as averages over 50m sub section lengths i The road geometry ii The 3m and 10m moving average longitudinal profile variance in each wheelpath iii The 3 m and 10 m enhanced longitudinal profile variance
133. radient whichever is greater The difference between the measured gradient and the Reference Gradient shall never exceed 6 0 gradient e 95 of the differences between the measured Cross fall and the Reference Cross fall fall within 1 5 crossfall or 10 of the Reference Cross fall whichever is greater The difference between the measured cross fall and the Reference Cross fall shall never exceed 6 0 crossfall e 65 of the differences between the measured Curvature and the Reference Curvature fall within 0 0015m 113 SCANNER User Guide and Specification Volume 5 8 6 8 6 1 8 6 2 8 6 3 8 6 4 8 6 5 8 6 6 8 6 7 114 e 95 of the differences between the measured Curvature and the Reference curvature fall within 0 003m Site tests of longitudinal profile The site tests of longitudinal profile described in the following sections will be carried out on the longitudinal profile recorded in both wheelpaths The tests will be passed if the measurements provided in both wheelpaths satisfy the specified requirements The Accreditation Tester selects a test site and divides it into a number of Sections marking the start and end of each section with a reflective post The site may contain both straight and curved Sections but will not contain any extremes of geometry The Accreditation Tester measures the longitudinal profile of the site using the Reference Method given in Table 8
134. ragraphs 5 5 12 through 5 5 14 Calculate further derived parameters from the dataset of individual RMST values paragraphs 5 5 15 through 5 5 21 Mean RMST values and the further derived parameters are output in the HMDIF file 67 SCANNER User Guide and Specification Volume 5 5 5 2 5 5 4 68 Filtering The filter is a band pass filter that attenuates wavelengths shorter than 10mm and greater than 100mm the frequency response is defined by fr 1 100 fu 1 10 Note These should be parameterised in software The filter is defined by a set of m plus one coefficients _ R f A where A is the interval between profile points 1 f_ is expressed in the same units as A R is the Filter Order which should have a default value of 3 but which should be parameterised in the software The calculated value of m should be rounded up to the next even integer There are m 1 low pass coefficients blp These coefficients define a low pass filter which attenuates frequencies higher than the frequency limit f The values of blp are initially determined by blip Hi sinc 2z i f A for i m 2 m 2 1 m 2 Where H are the coefficients of a Hamming window given by Hj 0 54 0 46 cos 2 z i m 2 m sinc x sin x x ifx 0 OR sinc x 1 if x 0 m 3 14159 f fy i e equal to the upper frequency limit of the filter expr
135. rch Other Visible Defects available on the UK Roads Board website This measure is not part of the SCANNER specification However the approach described in the research might be developed to detect and report other visible defects The approach would be applied to deliver a parameter describing the intensity of the other defects within the Scanner RCD or BCD 143 SCANNER User Guide and Specification Volume 3 144
136. re Lsi2 100 S12 Te Transverse variance The transverse variance for each reporting length L is obtained from the valid cleaned transverse profiles with the slope and offset suppression Section 3 5 4 applied within that length For definitions relating to this algorithm see section 3 3 However the following further definitions apply y cleaned transverse profile dmax position index of the road edge location within the cleaned transverse profile TpirFave Difference between the left and right transverse profile variance units of mm Evaluating the left and right half transverse profile variances for each profile The cleaned profile contains N re sampled profile points Jo v The position of the road edge expressed as the re sampled profile position index is given as dmax Data from points to the left of dmax o i Vid m1 are Set to O Zero The procedure Slope and offset suppression defined in Section 3 5 4 is applied to the cleaned profile data Y before proceeding with the transverse profile variance calculations The variances of the profile heights within each half are calculated and reported as the left and right half variance values T and Tr This involves the calculation of the average of the cleaned profile heights for each half L and R The sample position where the split between the left and right halves occur is calculated as H These va
137. rut depths 57 64 As Cols 1 8 for next pair of rut depths 65 72 As Cols 1 8 for next pair of rut depths 73 80 As Cols 1 8 for next pair of rut depths Table 7 14 Record S6 1 Repeated as necessary to provide number of values as defined by length of survey and spacing of values 10 pairs of rut depths per record Note 1 An invalid rut depth value must be output as 9999 100 Section 8 Data File Formats Texture data 7 4 18 Record S7 1 Repeated as necessary to provide number of values as defined by length of survey and spacing of points Characters Description Format Value range 1 80 Up to 20 texture profile point 2014 999 to 999 values measured in 1 10mm see Note 1 below Table 7 15 Record S7 1 Repeated as necessary to provide number of values as defined by length of survey and spacing of points Note 1 An invalid texture profile point value must be output as 9999 Multiple Line Texture Values 7 4 19 Record S8 1 Repeated as necessary to provide number of values as defined by length of survey number of multiple line texture values and spacing of values Characters Description Format Value range 1 80 Up to 16 multiple line texture 1615 9999 to values RMST measured in 9999 1 10mm see Note 1 below Table 7 16 Record S8 1 Repeated as necessary to provide number of values as defined by length of survey number of multiple l
138. rval in metres between texture profile point readings typically approximately 0 001m e g For a moving average length of 0 005m and a readings interval of exactly 0 001m the number of points would be 5 63 SCANNER User Guide and Specification Volume 5 5 4 7 5 4 9 64 The number of profile points corresponding to a baseline length of B typically 0 1m is calculated as B es T rounded to the nearest even integer exact odd numbers rounded up where interval in metres between texture profile point readings typically approximately 0 001m e g For a baseline length of 0 1m and a readings interval of exactly 0 001m the number of points would be 100 Rounding to the nearest even number ensures that no point lies exactly at the mid point of the baseline The number of baseline lengths corresponding to the reporting length L over which MPD is to be averaged typically 10m is calculated as J nxl e g For 10m average lengths a baseline length of 0 1m and a readings interval of exactly 0 001m the number of baseline lengths would be 100 rounded down to the nearest integer For each texture profile point k a moving average sensor measurement Yk is calculated as follows m 1 k 1 k For to 5 where 7 k 2 1 and y sensor measurement at point j m 1 m 1 eat to 5 where T total number of readings in the survey For k 1 j i m 1 1 where jak oD 5 4
139. s identified and recorded Offset of each multiple line RMST value relative to the centre of the vehicle Note Longitudinal profile data is filtered to remove wavelengths above a certain value initially 100m All survey data must start at a distance of at least half that wavelength before the start of the first survey lane within the route against which the survey is to be fitted and will end at a distance of at least half that wavelength beyond the end of the last survey lane within the route If the data collection method requires a longer run in and or run out e g using the HRM principal for measuring longitudinal profile the additional data is included within the data file Location data For each node identified during the survey run the following data are provided Node label Chainage Geometric data For each interval as defined in the survey header data the following data are provided 7 3 4 7 3 5 7 3 5 7 3 6 7 3 9 7 3 10 Section 8 Data File Formats Co ordinates x y and z Status for co ordinates Gradient Crossfall Radius of curvature Deviation flag Longitudinal profile and speed data For each interval as defined in the survey header data the following data are provided Single profile point Average speed of the survey vehicle Transverse profile data For each interval as defined in the survey header data the foll
140. s survey routes appropriate for the surveys of these test sites and carries out at least two surveys over each site or more if requested by the Accreditation Tester The methods of identifying and measuring cracking intensity differ for different systems and the Contractor may need to calibrate the Survey Equipment to be able to measure cracking intensity on UK local road networks Therefore the Accreditation Tester provides the Contractor with a sample of the Reference Data for a length not exceeding 5km of the Reference Sites The Contractor may use this data to calibrate the crack identification system fitted to the Equipment After any necessary calibration of the crack identification system the Contractor carries out the surveys of the test sites and delivers the SCANNER RCD and the SCANNER HMDIF files from the test sites to the Accreditation Tester The Accreditation Tester processes the crack data provided by the Contractor in the SCANNER RCD to obtain the Cracking Intensity over each 50m long sub section The Accreditation Tester calculates the average Cracking Intensity and the Standard deviation of the Cracking Intensity recorded over all of the sub sections surveyed from the SCANNER RCD provided by the Contractor 123 SCANNER User Guide and Specification Volume 5 8 11 11 8 11 12 8 11 13 124 The Accreditation Tester subtracts the average Cracking Intensity from the Cracking Intensity and divides this by the st
141. s the rules defined in the SCANNER user guide for survey routes Volume 4 for recording the location of the remaining Section start points unless otherwise instructed by the Accreditation Tester Processes the survey data to obtain the SCANNER RCD and SCANNER HMDIF files noting the requirements of the SCANNER user guide Volume 4 concerning the delivery of the route information in the SCANNER HMDIF and SCANNER RCD files Following the completion of the survey carries out any necessary route alignment This includes obtaining the elapsed chainage of those Section start points for which OSGR co ordinates were provided by the Accreditation Tester Delivers the SCANNER RCD and SCANNER HMDIF files to the Accreditation tester for analysis and comparison with the Reference Data Delivers the coverage records as defined in the SCANNER user guide Volume 4 The Accreditation Tester evaluates the Network Level performance by comparing frequency distributions of the data from the whole of the test routes and by comparing detailed data from a sample of individual Sections with the Reference Data The tolerances allowed for the comparison of the measurements provided by the Contractor and the Reference Data are given in Table 8 3 The Network Test will be passed if all the following criteria are met The survey equipment is in the opinion of the Accreditation Tester able to operate safely whilst causing minimum disruption
142. set suppression 3 5 4 applied using only the points from position dmax to position N 1 This width becomes the full width W referred to in the following rut depth algorithm The size and boundaries of the quarters used by the algorithm will vary according to the edge location dmax General principles The general principle is to replicate the use of a 2m straight edge with one end positioned close to the left edge of the lane for the cleaned nearside rut and close to the right edge of the lane for the cleaned offside rut as shown in Figure 3 6 Cleaned rut depths are measured perpendicular to the straight edge 2m Straight Edge 2m Straight Edge 3 6 6 Nearside Rut Depth Offside Rut Depth Figure 3 6 Measurement of rut depth using 2m straight edge However before the cleaned rut depths can be calculated some basic checks are needed to eliminate unwanted sensor measurements and to identify inadequately measured profiles Unwanted measurements may be caused by the sensors overlapping a feature such as a kerb Inadequately measured profiles may be caused by there being insufficient sensors outside the wheel path The operation of determining each individual cleaned rut depth can therefore be broken down into three stages as shown in Figure 3 7 41 SCANNER User Guide and Specification Volume 5 Identify and eliminate any unwanted sensor measurements Soe Identify and exclude any inadequately measured pro
143. ssed as a percentage to one decimal place Transverse Cracking Intensity To calculate transverse cracking intensity the percentage of cracking within defined lengths of the survey data is evaluated using a moving window If the percentage area of cracking within this window exceeds a defined cut off value then all grid cells within the window are considered to have arisen from the presence of transverse cracks The calculation of transverse cracking intensity is carried out using the following configurable parameters The number of grid cells longitudinally used for the calculation of transverse cracks default 2 This defines the longitudinal length of the moving window used to identify transverse cracks The percentage of the area within the moving window considered for the identification of transverse cracking required to classify all grid cells within the window as transverse default 20 The length over which the transverse cracking intensities are to be calculated and reported typically 10m which shall be an integer multiple of the length of each grid cell The calculation of transverse cracking intensity is carried out using the following definitions The width of the window used for the identification of transverse cracking is the width of the survey as shown in figure 6 4 The calculation of transverse cracking intensity is carried out using the following rules Commencing at the start of the
144. st transverse profile for the averaging length paragraphs 3 4 17 through 3 4 23 Each valid individual transverse profile within the averaging length is correlated with the best transverse profile This determines the size and direction of the shift required for each transverse profile to obtain the optimum correlation paragraphs 3 4 24 through 3 4 32 Section 3 Transverse Profile Parameters The position of the edge of the road in each individual transverse profile en is found using the size and direction of the shift established in step f above paragraphs 3 4 33 through 3 4 39 Data to the left of this point is defined as being off the road verge kerb etc data to the right of this point is defined as being on the road The transverse profile is now defined as cleaned The cleaned transverse profile does not contain data defined as being recorded off the road 3 4 5 The process is summarised in the flow diagram of figure 3 3 25 SCANNER User Guide and Specification Volume 5 Main input parameters Matrix of transverse profiles Averaging length Sensor spacing U Resample profiles For each averaging length Calculate average profile Smooth average profile For each transverse profile within the a averaging length A gt Correlate transverse profile Compute maximum shift and edge position EEEEELETETTETS S TCC LLL CELL spielen orem EEETETTTECTETTETE SPP Ko
145. survey evaluate the percentage area of cracking within the window If the percentage of cracked grid cells within the window exceeds the defined percentage all grid cells within this window are considered to have arisen from the presence of transverse cracks as shown in Figure 6 4 79 SCANNER User Guide and Specification Volume 5 Move the window down the survey by one grid cell and repeat the assessment If a cracked grid cell is classified as transverse in one window but not classified in an adjacent window the crack should be recorded as transverse The transverse cracking intensity should be expressed as the percentage of grid cells within the surveyed area for each configurable length that have been classified as arising from transverse cracking Full survey width Full survey width Centre Line Centre Line Transverse crack Cracked grid cells in 0 4m length subsection 13 Total number of grid cells in 0 4m length subsection 32 41 gt 20 Hence classify as transverse Figure 6 4 Classification of transverse cracking within the crack grid 6 7 Surface Deterioration Intensity 6 7 1 To calculate the surface deterioration intensity each cracked grid cell within the crack grid is examined and the position size and the number of cells in the surrounding area reviewed 6 7 2 The calculation of surface deterioration features intensity is carried out using the f
146. t Mean Square Texture Depth Individual Root Mean Square Texture Depth RMST values are calculated over the individual RMST calculation length Lams for each filtered texture profile measurement line The individual RMST values are calculated as 1 N RMST A where 1 zj is the height of the filtered texture profile point j in mm N is the number of filtered profile points within each individual RMST calculation length Lrms Lrms has a typical value of 0 1m but should be parameterised Mean Nearside RMST Mean nearside RMST values are obtained by averaging the valid individual RMST values from texture measurement lines lying within a distance of 0 3m of the nearside wheel path Note The position offset of the nearside wheel path will be determined during the acceptance tests of the Equipment 1 m Meanpryusr ys 5S M iz 5 5 13 5 5 14 5 5 15 Section 5 Texture Profile Parameters where for each measurement line i lying within 0 3m inclusive of the nearside wheel path 1 nval gt RMST and where j l S RMST is the individual RMST value reported over interval j in a single measurement line nis the number of individual RMST values within a mean RMST reporting length L for a single measurement line S is the average of the valid individual RMST values from a single measurement line over the mean RMST reporting length L Invalid in
147. t of values all records except the last are utilised and unused values within the last record should be set to blank or zero as appropriate e g If the length of survey and spacing of texture data define there to be 50 000 004 texture profile point values recorded there should be 2 500 001 texture data records type S7 1 with the first 2 500 000 records having 20 values in each and the last record having 4 actual values and 16 values of zero Within each record type data is output in order of increasing survey chainage The following convention is used within the Format column An indicates a text field of n characters left justified and padded with spaces In indicates an integer numeric field of up to n characters including an optional leading sign right justified and padded with spaces mlin indicates m consecutive fields of format In Fn d indicates a real number field of up to n characters including the decimal point and an optional leading sign with d digits after the decimal point right justified and padded with spaces mFn d indicates m consecutive fields of format Fn d The Contractor agrees the machine Equipment identifier with the Auditor Survey header data Record S1 1 Single Record Characters Description Format Value range 1 6 SCNO71 A6 7 14 Machine identifier A8 15 25 Date at the start o
148. taining the carriageway cracking grid The carriageway cracking grid is obtained from the crack map provided in the survey data by overlaying the crack map with a 2 dimensional rectangular grid This is illustrated in figure 6 1 for a typical Scanner survey vehicle within a 3 2m survey width The carriageway cracking grid is obtained using the following configurable parameters Width of each grid cell typically 200mm Number of cells across the grid to be agreed during the acceptance tests Offset of the centre of the grid from the centre of the vehicle survey typically zero Length of each grid cell typically 200mm Note that The grid may not cover the full width of the crack detection system i e cracks may start and or end outside the grid Alternatively the grid may extend beyond the full width of the crack detection system Section 6 Cracking Parameters Centreline of survey 20 cells 16 cells q Bee Cell considered as containing crack i Cell considered as not containing crack Figure 6 1 Crack map overlaid with grid to obtain the carriageway cracking intensity 6 4 3 The carriageway cracking grid is obtained using the following rules Where a crack starts or ends exactly on a line or corner point between grid cells or passes through a corner point the principles shown in Figure 6 2 are applied The crack is only considered to be within the cell s from which
149. tation Tester selects a road network consisting of many Sections The network will include road types that are typical of the overall local road network in terms of construction condition and traffic levels and in proportions that broadly reflect the proportions to be found on typical local authority road networks Where possible the Accreditation Tester will select test routes for the Consistency Tests that coincide with the routes used for the Network Tests component of the Accreditation tests The process for the consistency testing shall follow the requirements for network route surveys described in Section 8 13 Sub sections 8 13 1 to 8 13 9 However The Accreditation Tester analyses all data collected for the sample networks at a 10m sub section level The Accreditation Tester also calculates the SCANNER RCI for each 10m sub section The Accreditation Tester compares the values of the SCANNER Road Condition Indicator with the reference measurements to 10 3 10 3 1 10 3 2 Section 10 Consistency Tests obtain an estimate of the bias in the SCANNER Road Condition Indicator The Accreditation Tester compares the values of the SCANNER Road Condition Indicator obtained from repeat runs from accredited SCANNER equipment to obtain an estimate of the random error in the SCANNER Road Condition Indicator Reporting consistency measurements The Accreditation Tester determines the bias and standard deviation of
150. tes the average Cracking Intensity and the standard deviation of the Cracking Intensity recorded over all of the sub sections surveyed in the Primary Reference Dataset The Accreditation Tester subtracts the average Cracking Intensity from the Cracking Intensity and divides this by the standard deviation of the Cracking Intensity for each sub section 8 11 6 8 11 7 8 11 8 8 11 9 8 11 10 Section 8 Accreditation Testing to obtain the Normalised Cracking Intensity for each of the 50m sub sections Note the data will now have an average value of 0 anda standard deviation of 1 The Accreditation Tester calculates the 75th and 88th percentile values of the Normalised cracking data for each sub section Sub sections with a Normalised Cracking Intensity greater than the 88th percentile value are defined as sub sections containing high levels of cracking Sub sections with a Normalised Cracking Intensity less than the 88th percentile value but greater than the 75th percentile value are defined as sub sections containing moderate levels of cracking Sub sections with a Normalised Cracking Intensity less than the 75th percentile value will be defined as sub sections containing low levels of cracking The Accreditation Tester provides the Contractor with a map showing the location of the test sites and the description of each Section start and end point on each test site The Contractor define
151. the moving average sensor measurements y but moving average sensor measurements need not be calculated at those points and are not used in calculating the individual or average MPD values When a texture profile point reading falls exactly on the boundary between two reporting lengths it is deemed to lie within the former of those lengths e g With a reporting length of 10m a baseline length of 0 1m and an interval between texture profile point readings of exactly 0 001m the 10 000th texture profile point reading at chainage 10m is deemed to lie within the 0 10m reporting length Multiple Line Root Mean Square Texture Depth RMST Multiple line Root Mean Square Texture Depth values are provided in the RCD and HMDIF files RMST values are calculated from the measurement of the texture profile as described in the following paragraphs Subsequent to obtaining RMST values further derived parameters may be obtained e g variance in RMST for output in the HMDIF The methodologies for obtaining these parameters is also described below For each texture profile line i Filter each texture profile measurement using a bandpass filter paragraphs 5 5 2 through 5 5 10 ii Calculate over lengths of 0 1m individual Root Mean Square Texture Depth RMST values paragraph 5 5 11 Individual RMST values are output in the RCD file Obtain the Nearside Middle and Offside Mean RMST values pa
152. the survey deviated from the defined route over all or part of the length ending at the chainage of this record 52 Spare A1 as Table 7 11 Record 3 1 Repeated as necessary to provide number of measurements as defined by length of survey and spacing of values Note 1 An invalid gradient must be output as 999 9 Note 2 An invalid crossfall must be output as 999 9 Note 3 An invalid radius of curvature must be output as 99999 99 7 4 15 Section 8 Data File Formats Longitudinal profile and speed data Record S4 1 Repeated as necessary to provide number of values as defined by length of survey and spacing of points speeds 7 points speeds per record Characters Description Format Value range 1 7 Nearside profile point value 17 999999 to measured in 1 10mm see Note 999999 1 below 8 14 Offside profile point value 17 999999 to measured in 1 10mm see Note 999999 1 below 15 18 Speed value measured in 14 0 9998 cm sec see Note 2 below 19 36 As Cols 1 18 for next profile points and speed 37 55 As Cols 1 18 for next profile points and speed 56 72 As Cols 1 18 for next profile points and speed Table 7 12 Record S4 1 Repeated as necessary to provide number of values as defined by 7 4 16 length of survey and spacing of points speeds 4 points speeds per record Note 1 An invalid profile point value must be output as 9999999
153. these over 10m lengths The Accreditation Tester subtracts the calculated Cleaned Rut Depths from the Cleaned Rut Depths measured with the Reference Method The test is passed if all the following criteria are met The visual examination of the transverse profile confirms that the Equipment is not adversely affected by the measurement of transverse profile over the road edge 65 of the differences between the measured Cleaned Rut Depths in each Wheelpath and the Reference Cleaned Rut Depth in each Wheelpath fall within 1 5mm 95 of the differences between the measured Cleaned Rut Depths in each Wheelpath and the Reference Cleaned Rut Depth in each Wheelpath fall within 3 0mm All of the differences between the measured Cleaned Rut Depths in each Wheelpath and the Reference Cleaned Rut Depth in each Wheelpath are less than 10 0mm or 50 of the magnitude of the Reference Cleaned Rut Depth whichever is the greater e 65 of the differences between the measured Transverse Unevenness in each wheel path and the Reference Transverse Unevenness fall within 0 003 e 95 of the differences between the measured Transverse Unevenness in each wheel path and the Reference Transverse Unevenness fall within 0 006 65 of the differences between the edge roughness calculated from the measured Transverse Profile over 10m lengths and 117 SCANNER User Guide and Specification Volume 5 8 8 8 8 1 8 9 8 9 1 11
154. ting conditions on one or more routes selected by the Accreditation Tester and located on the public road network In the survey data Accreditation tests the data output from the Equipment is checked to ensure that it complies with all the requirements for loading into a UKPMS accredited system If the Equipment fails to achieve the required levels of accuracy in the measurement of individual parameters the machine developer or Contractor may seek to resolve this issue by enhancing the performance of the Equipment The Accreditation Test for that measurement may then be repeated at the Contractor s expense at a time convenient to both the Accreditation Tester and the machine developer or Contractor Any SCANNER surveys that may have been completed in the Accreditation Approval Period may also be invalidated and need to be repeated at the Contractor s expense On successful completion of the Accreditation Tests including the survey data Accreditation testing the Accreditation Tester issues an Accreditation Certificate similar to the example in Figure 8 1 which summarises the results of the Accreditation Tests in the measurement of each defined survey parameter The initial accreditation certificate is valid up to 14 months from the date of issue At intervals of no more than one year following the commencement date of the Accreditation Certificate the Contractor submits the survey equipment for Accreditation re testing The Accred
155. to be classified as a wheel track crack typically 90 degrees i e effectively no limit but may be reduced as a result of the acceptance tests The length over which the cracking intensities are to be calculated and reported typically 10m which shall be an integer multiple of the length of each grid cell The left wheel track cracking intensity and right wheel track cracking intensity are calculated and reported individually The principle applied in the calculation of left wheel track cracking intensity is shown in Figure 6 7 Calculation of the right wheel track cracking intensity is simply a mirror image Note The offsets and grid widths used in the calculation of wheel track cracking intensity may differ from the dimensions used in the calculation of carriageway cracking intensity and may even differ from the dimensions used in determining whether cracks are wheel track cracks 83 SCANNER User Guide and Specification Volume 5 20 cells 6 8 4 6 9 6 9 1 84 Centreline of survey left wheel track crack Number of grid cells containing at least one left wheel crack 9 Total number of grid cells 20 Intensity of left wheel track cracking 9 20 100 45 0 left wheel track crack Figure 6 7 Obtaining left wheel track cracking intensity The wheel track cracking intensities are expressed as a percentage to one decimal place Typical Values Checks and Limits Typical va
156. to other road users In the opinion of the Accreditation Tester satisfactory procedures have been implemented by the Contractor for route planning and carrying out the survey The data provided by the Contractor meet the tolerances given in Table 8 3 The data provided by the Contractor comply with the requirements for coverage for each measured parameter given in the specification for SCANNER accredited surveys 129 SCANNER User Guide and Specification Volume 5 Parameter Measured Tolerance Tolerance 90 Limits Maximum Error Section Lengths 5m or 0 1 50m or 10 National Grid Co ordinates of Section 5m 50m Start Point Altitude of Section start point 10m 50m National Grid Co ordinates where 7m 50m GPS gt 70 National Grid Co ordinates where 15m 50m GPS lt 70 Altitude where GPS gt 70 10m 50m Altitude where GPS lt 70 15m 50m Road Geometry Gradient 1 5 or 10 6 Road Geometry Crossfall 1 5 or 10 6 Road Geometry Curvature 0 003m 0 005m 3m Moving Average and Enhanced 0 6 N A Longitudinal Profile Variance in each wheelpath 10m Moving Average and Enhanced 0 7 N A Longitudinal Profile Variance Transverse Unevenness 0 006 0 05 Edge Roughness 0 05 0 3 Rut Depth and Cleaned Rut Depth 3 0mm 50 of True Rut Depth or 10mm Nearside SMTD 0 25mm 0 75mm Nearside Middle and
157. ut The Accreditation Tester assesses the SCANNER RCD and SCANNER HMDIF files from the Contractor s re testing surveys against the reference methods described in Table 8 1 for site tests Section 8 13 for network tests and Section 9 for the survey data acceptance tests On completion of these tests the Accreditation Tester approves the system for the delivery of SCANNER HMDIF files 11 1 11 11 1 12 11 1 13 11 1 14 11 1 15 11 1 16 Section 11 Accreditation Re testing If the survey equipment meets the requirements for accuracy in the re test then the Auditor will issue an accreditation certificate for a further 12 months An example re testing timetable is given in Figure 11 1 If the survey equipment fails to meet the requirements for accuracy in the re test then any current Accreditation Certificate becomes invalid any data collected by the Equipment since the last successful weekly check on a Reference Test Site see requirements for Quality Assurance and Audit in the SCANNER User Guide volume 4 are invalid and any results reported from that data are not acceptable as SCANNER accredited surveys If a Contractor makes any significant change to the Survey Equipment after the issue of an Accreditation Certificate the Auditor may require the Survey Equipment to be submitted for an additional Accreditation re test During the retesting the Contractor uses the same survey equipment and settings that are employed by for rout
158. viding alternative measurements on these areas Note Options for this might include for example the commissioning of alternative surveys by the Employer to provide this data or the provision of this data by the Contractor using alternative survey methods These options may have cost 125 SCANNER User Guide and Specification Volume 5 8 11 19 8 11 20 8 11 21 8 11 22 126 implications which the Employer and Contractor should clarify before letting any contract The Accreditation Tester uses Secondary Reference Data to assess the sensitivity and accuracy of the Equipment in relation to other Equipment operated by others that provides measurements of cracking These comparison tests can therefore only be carried out when data from the test sites is provided by more than one set of Equipment The Accreditation Tester assembles data provided from surveys of the test sites by each piece of Equipment to form the Secondary Reference Data The Accreditation Tester obtains the Cracking Intensities from the SCANNER RCD or SCANNER HMDIF files provided by each set of Equipment participating in the Site Tests of cracking expressed over 50m sub section lengths The Accreditation Tester examines all the data from each set of Equipment and removes any measurements of Cracking Intensity that are not representative of the overall levels reported by that set of survey equipment outlying data values
159. ving average variance enhanced variance bump measure is the checked longitudinal profile data The following processes are applied separately to the longitudinal profile data recorded in the nearside and offside wheelpaths to obtain the parameters for each wheelpath Checking the longitudinal profile data Any parameter derived from the longitudinal profile data over any length L shall be considered invalid and therefore not output in the HMDIF file if any single profile point used to calculate that parameter over that length was invalid During the acceptance tests the Equipment is assessed to determine the minimum speed and maximum levels of acceleration and deceleration under which surveys can be carried out from which valid measurements of the derived parameters can be calculated The acceptance tests determine the minimum speed V3 and V10 and the maximum levels of acceleration and deceleration for the calculation of valid 3m variance 10m variance and the bump measure which are defined as Amax3 and Amaxto The acceptance tests also determine the length of survey required following the end of a period of acceleration or deceleration that must elapse before the survey measurements can be considered valid defined as LRecovery 2 2 5 2 2 6 2 2 7 2 2 8 2 2 9 2 2 10 2 2 11 Section 2 Longitudinal profile parameters Checking survey speed The bump measure 3m moving average Longitudinal Profile Variance
160. wn at the road edge percentage of reporting length Ls 2 Large step down at the road edge percentage of reporting length For definitions relating to this algorithm see section 3 3 However the following further definitions apply V is the number of the first transverse profile point located to the left of or at the edge position en R is the number of the first transverse profile point located to the right of and not equal to the edge position en R2 is the number of the last or rightmost transverse profile point located to the left of or at a position 1m to the right of the position defined by en i e at the position en 1000mm 51 SCANNER User Guide and Specification Volume 5 Profile points Located Road Linear fit to profile points R Rz e Profile points edge position e Y mxi c where step height evaluated So sllax i sif i s gt sMin y mes Hi Px Xo X Ez e 1000mm V 3 R 4 R2 9 Figure 3 14 Calculation of the edge step height measurements obtained from the transverse profile 3 8 4 Obtain the least squares best fit line for the transverse profile measurements recorded between position Xpr and position Xp2 Shown in Figure 3 15 in green The least squares fit will define a line Y mxj c where Y is the line height value at any transverse position xi m is the gradient of the line and c is the value of Y at transverse position X
161. x for the re sampled transverse positions with range 0 1 N 1 the parameter N is taken as per the definition in paragraph 3 3 1 r d is the correlation vector as calculated in paragraph 3 3 30 The correlation at zero lag d 0 is in r 0 the correlation at lag 1 d 1 is inr 1 and so on The components of r d are the values of the correlation at different lags d A maximum value of r d rmax d is sought by calculating r d for all 0 lt d lt N 2 dmax s defined as the lowest value of d where rmax d occurs as shown in Figure 3 4 Note sample code in C is available from TRL Limited demonstrating the procedures to be followed in order to calculate dmax Compute the maximum shift and the edge position The following defines the method for locating the edge of the road in each transverse profile The shift value is defined as the lag where the maximum correlation occurs dmax as found in 3 4 32 dmax defines how many re sampling steps from the position of the first sensor on the transverse profile have measured features to the left of the road edge verges kerbs etc dmax Multiplied by the re sampling interval t defines the edge position along the transverse profile en where n indicates the re sampled transverse profile being considered 3 4 43 3 4 44 3 4 45 3 5 3 5 1 3 5 2 3 5 3 Section 3 Transverse Profile Parameters Cn dmax t Data from me
162. xA for which x lt q and Xa Sx t itA If smoothing of the transverse profile data takes place as described in Section 3 4 7 then each value of yi in subsequent analyses is replaced with the corresponding value of gi Re sampling If q is the number of data points in a transverse profile x y is a set of data points comprising an individual transverse profile the cubic spline is applied as follows Oi 0 Oia 1 1 h_ h h_ h A 6 i l 3 i a 6 i h OAN y h y Yia with i 1 2 3 q 2 where h x x s the spacing between two adjacent profile points o the second derivative of the profile at i The second derivatives are calculated in order to ensure second order continuity 27 SCANNER User Guide and Specification Volume 5 3 4 11 3 4 12 3 4 13 3 4 14 28 The equation above requires boundary conditions which are the actual transverse profile height at points i 0 andi q 1 At these points the first and second derivatives are assumed to be equal to zero The equations above in paragraph 3 4 10 defining a set of algebraic equations are solved for unknown value o The algorithm recommended for solving a tri diagonal matrix is given in Section 3 4 14 The re sampled profile defined by 5 is calculated by computing the following coefficients a o O 6h L b o 2 c via y h Gin 26 h 6 d y with i 0 1 2 q 2 and h

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