User's Guide Nord2000 Road
Contents
1. ccccecescccesssceesseeesseeeeeecesseeessseeeeseecssseeesseeeseeeeessesesseeesaes 33 5 3 Required Accuracy of Input Data ssasa ss 35 Page 3 of 51 Appendix 1 Source Emission Compared with the Old Model scssssssssessseees 37 Appendix 2 User Defined Road Surface Correction sccssccsscsssesssssessessssseseees 39 Appendix 3 Main Categories and Subcategories of Vehicles scsccsssessssseseees 40 Appendix 4 Weather Conditions cccccsecssccrscersscosscosscnssscorscoasssssconsconsssesssonsoonsons 41 Appendix 5 Accuracy of Predicted Road Traffic Noise Levels sscsscssssssseees 47 Referentes sccccenscnussssccnssssccussesccusecsenesesusenscnsaensccasesscnadsusenashssseuseesenesesscesssussentenasssensssesesseusee 50 Page 4 of 51 Users Guide Nord2000 Road Foreword In 1996 the Nordic Council of Ministers decided to initiate the development of a new gen eration of prediction methods for environmental noise utilising scientific development having taken place since the first Nordic methods were published in the 1970s and 1980s The idea was to develop a general sound propagation model and to establish source speci fic prediction methods for road and rail traffic and other types of environmental noise sources All prediction methods should be based on the same general propagation model The sound propagation model should be applicable for computing the sound pressure level caused2. 9 N 75 x o E ra lt a 70 Nord2000_DK_Cat 3 5 Nord2000_DK_Cat 2 65 NBV_96_Heavy Nord2000_DK_Cat 1 NBV_96_Light 60 l 20 40 60 80 100 120 140 Speed km h Figure 15 L4Fmax at 7 5 m distance from a Danish vehicle as a function of vehicle speed according to the old method NBV_96 12 and the new Nord2000 Road Page 38 of 51 Appendix 2 User Defined Road Surface Correction In the Nord2000 Road model only the most common road surfaces are taken into account For other road surfaces it is difficult to make general corrections Nominally the same road surface may have different properties depending on where and when it was constructed Thus each user preferably each national road administration is recommended to deter mine the correction in each individual case This is most simply done by carrying out pass by tests and then comparing with measurement results or calculation results for a reference surface Preferably the tests shall be carried out according to methods proposed within the European SILVIA project The difference can then be stated as AL surface 2 dB rel Nord2000 Road reference surface average between DAC 11 and SMA 11 AL surface 1s often different for light and heavy vehicles ALsurtace can either be given for each one third octave band or for the total A weighted value If only the A weighted correction is used it has to be applied equally for each frequen
3. The turbulence strength corresponding to the wind C accounts for the turbulent motion of the atmosphere The parameter is not available in standard weather data The maximum observed value of C is approx 0 3 ms and it is recommended to use a value of 0 12 m s unless other information is available The turbulence strength corresponding to the temperature Cr accounts for the turbulent variation of the temperature in the atmosphere The parameter is not available in standard weather data The maximum observed value of Cr is approx 0 05 Ks and it is recom mended to use a value of 0 008 Ks unless other information is available The standard deviation of the wind speed in the direction of propagation o accounts for the fluctuation in wind speed in excess of what is already included in the turbulence strength Turbulent motion is fluctuations taking place within seconds or minutes For cal culation of instantaneous sound pressure levels o shall be zero For calculation of the equivalent sound pressure level with duration above a few minutes up to a few hours the Page 42 of 51 A 4 2 l SINTEF Vyr effect of slow variations in wind speed can be taken into account by this parameter The parameter should not be used for calculating long term effects where the weather is basi cally changing during the time Instead a procedure where the weather is divided into a number of meteorological classes should be used The s
4. Page 28 of 51 4 1 4 1 1 Special Procedures Special Maximum Noise Levels Energy Mean and Arithmetic Mean Value When the maximum sound pressure level is calculated from the sound power levels de fined in 4 the result is an energy mean value This mean value shall be converted to the arithmetic mean value For a normal distribution with standard deviation o the relation between energy mean value Lem and arithmetic mean value L is shown in Eq 3 and Figure 9 L L 0 05 In 10 o 3 Difference dB 3 0 2 5 2 0 1 5 1 0 0 5 0 0 0 1 2 3 4 5 Figure 9 Difference between energy mean value and arithmetic mean value for anormal distribution of maximum noise levels If the standard deviation is unknown the values from 12 shown in Figure 10 may be used Page 29 of 51 4 1 2 4 1 3 Standard deviation dB 4 0 3 0 2 0 1 0 Vehicle speed km h 0 0 20 40 60 80 100 120 140 Figure 10 Standard deviation of maximum noise levels from heavy and light vehicles 12 Maximum Level Exceeded by 5 of the Vehicles The maximum noise level exceeded by 5 of the vehicles of a category can be determined by adding 1 65 times the standard deviation s to the arithmetic mean value ZL pa presup posing a Gaussian distribution L Lirmx 1 65 s 4 max 5 If the standard deviation is unknown the values from 12 shown in Figure 10
5. sources representing the traffic noise radiated from a tunnel opening is given in 13 Table 14 Default sound absorption coefficients for use in cases when no information is available on the tunnel interior surface properties Frequency range Hz lt 125 160 400 500 1250 gt 1600 1 Smooth concrete 0 08 0 08 0 08 0 08 2 Rough concrete 0 08 0 11 0 14 0 14 3 Sound absorbing treatment 0 15 0 5 0 8 0 65 Page 31 of 51 4 3 Figure 12 Illustration of the position of four noise sources representing the sound radiated from a tunnel with a semi circular cross section with radius R 13 Sound Transmitted through Facades According to ISO 140 5 14 the sound pressure level Zin indoors 1s given by S L L R 101g a 3 6 where Lr is the calculated free field level outdoors R is the sound reduction index of the facade S is the wall area of the facade and A is the equivalent sound absorption area of the room A can either me estimated in octave bands using tables in EN ISO 10052 15 measured or for common dwelling estimated using the equation A 32 V 7 where Vis the volume of the room in m The one third or octave band sound pressure levels obtained are then to be A weighted and added to yield the overall A weighted sound pressure level indoors Page 32 of 51 5 1 5 2 Accuracy Nord2000 Road has not yet been applied to computations by numerous users and it
6. 0 0 0 0 0 2 6 29 8 1 8 0 0 0 0 0 3 20 8 0 3 0 0 0 0 0 0 13 1 3 9 1 4 0 0 0 0 3 1 0 8 0 0 0 2 22h 0 0 0 0 0 0 2 7 28 7 2 0 0 0 0 0 0 3 21 0 0 2 0 0 0 0 0 0 12 5 3 8 1 3 0 0 0 0 3 6 0 9 0 0 0 2 23 3 0 0 0 0 0 0 2 8 27 2 2 0 0 0 0 0 0 1 22 1 0 3 0 0 0 0 0 0 12 5 3 5 1 3 0 0 0 0 3 6 1 2 0 0 0 2 23 7 0 0 0 0 0 0 2 6 25 5 2 2 0 0 0 0 0 1 22 8 0 3 0 0 0 0 0 0 12 5 3 1 1 2 0 0 0 0 4 4 1 5 0 0 40 0 0 0 1 22 4 0 0 0 0 0 0 250 25 1 2 3 0 0 0 0 0 5 22 0 0 3 0 0 0 0 0 0 13 4 3 1 1 0 0 0 0 0 5 7 155 0 0 50 0 0 0 1 20 5 0 0 0 0 0 0 2 4 25 4 2 5 0 0 0 0 0 3 22 6 0 2 0 0 0 0 0 0 14 2 3 4 0 8 0 0 0 0 6 0 1 4 0 0 60 0 0 0 1 18 3 0 0 0 0 0 0 2 3 27 3 255 0 0 0 0 0 1 22 3 0 2 0 0 0 0 0 0 14 6 4 0 0 8 0 0 0 0 6 3 153 0 0 70 0 0 0 1 17 4 0 0 0 0 0 0 2 3 27 0 2 5 0 0 0 0 0 1 21 3 0 4 0 0 0 0 0 0 15 8 4 2 0 7 0 0 0 0 7 2 1 0 0 0 80 0 0 0 1 14 4 0 0 0 0 0 0 1 8 28 4 225 0 0 0 0 0 4 20 8 0 5 0 0 0 0 0 0 18 3 4 1 0 7 0 0 0 0 7 0 1 0 0 0 90 0 0 0 1 11 2 0 0 0 0 0 0 1 5 30 0 2 4 0 0 0 0 0 2 21 2 0 6 0 0 0 0 0 0 20 7 4 1 0 7 0 0 0 0 6 4 0 8 0 0 100 23 0 0 5 0 0 0 0 0 0 21 7 4 1 0 7 0 0 0 0 7 3 0 7 0 0 110 0 0 0 0 7 1 0 0 0 0 0 0 1 6 2555 2 1 0 0 0 0 0 1 27 4 0 5 0 0 0 0 0 0 22 4 3 7 0 7
7. 0 0 0 0 7 9 0 9 0 0 12 0 0 0 0 0 21 E 0 0 0 8 0 For the time of day period and for each source point the sound pressure level is the energy average of the calculation result Lm in each meteo class weighted with the percentage pm of the class as shown in Eq 11 Lm is calculated using the weather parameters Am and Bm and the temperature t and relative humidity RH of the meteo class 25 Piens 10 Ig 2 m l Page 44 of 51 100 Lin An 2B imstm gt RH n Pm 19 mtm 10 11 A 4 3 For transmission paths not directly from the source to the receiver such as those of reflect ed sound or sound diffracted around the vertical edges of a finite screen the percentage pm must be determined taking the actual propagation directions into account In principle a calculation has to be carried out for each of 25 classes but in practice only 13 classes seem to contain occurrences and 3 5 of them seem to contain so few occurrenc es that the number of classes can be reduced to 8 10 In order to reduce the calculation time in rough calculations the number may be reduced to 4 or 5 classes or maybe even less by combining some of the meteo classes When calculating the yearly average the remaining parameters should be e C 0 12 m s e CF 0 008 Ks e o 0m s Oatidz 0 Calculation for Specific Weather The most interesting specific weather is the reference weather of the o
8. 0 4 8 Range 2 9 3 8 5 6 D The yearly average air temperature in Finland 1971 2000 northern part 2 0 C central part 1 2 C southern part 5 C The yearly average daily temperature is 1 0 C the range is 0 5 3 7 C depending on region 9 The averages given are for Stockholm the ranges show the variation between regions Page 19 of 51 3 2 3 2 1 Corrections may be made to take into account the influence of a film of water on the road surface 4 This correction is valid for light vehicles only and it has not been possible to show a similar relationship for heavy vehicles In order for this correction to be applied it is not enough that the surface looks wet It literally has to be covered with a distinct film of water Driving conditions All default sound power coefficients in 4 refer to free flowing traffic at constant speed The propulsion noise from Category 2 and 3 vehicles can be corrected for acceleration de celeration on long road gradients according to Figure 6 In urban traffic and start stop situ ations the propulsion noise should be corrected with 3 dB Correction dB 12 Gradient 0 5 10 15 20 Figure 6 Correction of propulsion noise from Category 2 and 3 vehicles on long gradients Propagation Computation Point Height The computation point receiver height is the height above the local terrain Guidelines regional or
9. A is the logarithmic weather coefficient B is the linear weather coefficient and C is the sound speed at the ground c 0 Zo A B and C depend on which type of noise level shall be calculated A B and C must be determined on the basis of weather data from synoptic stations such as the e wind speed in m s measured at a specified height normally 10 m above ground e wind direction in degrees e stability of the atmosphere normally determined indirectly on the basis of wind speed cloud cover time of day e air temperature t in C For a meteorologically neutral atmosphere the wind contributes to the logarithmic part of the vertical sound speed profile and the temperature variation with the height contributes to the linear part of the profile In this case A will be determined by the wind speed and direction while B corresponds to a decrease in temperature of 1 per 100 m the adiabatic lapse rate C is determined by the air temperature If the atmosphere is not neutral the determination of A and B is more complicated see Section A 4 4 Other meteorologically defined parameters in Nord2000 Road are the e turbulence strength corresponding to wind C in m 3s e turbulence strength corresponding to temperature Cr in Ks e standard deviation of the wind speed in the direction of propagation ow in m s e standard deviation of fluctuations in the temperature gradient Odtdz in C m e relative humidity RH in
10. B Plovsing and J Kragh Nord2000 Comprehensive Outdoor Sound Propagation Model Part 2 Propagation in an Atmosphere with Refraction DELTA Acoustics amp Vibration Report AV 1851 00 revised Hersholm 2006 e R Eurasto Nord2000 for road traffic noise prediction Weather classes and statistics VTT Research Report No VTT R 02530 06 Esbo 2005 e The present User s Guide Equations for graphs in this User s Guide are given in the reports above What Can Be Calculated Nord2000 Road can be used to calculate Leq overall A weighted or in frequency bands for any combination of road vehicles provided input data are available The maximum sound pressure level corresponding to time weighting F can be calculated from individual ve hicles or combinations of vehicles at specified positions However the prediction method does not give statistical methods to calculate maximum levels from passing groups of ve hicles The assessment points should be chosen in accordance with the recommendations in 1 The prediction method separates tyre road noise from propulsion noise Thus the method can be used to estimate the effect of changing road surface or tyres For the most common types of road surfaces default values are given It is also possible to calculate the effect of studded tyres and of vehicle acceleration and to correct the tyre road noise generation for Page 7 of 51 1 2 l SINTEF KA V TR variation in air temperature The m
11. Page 47 of 51 and for traffic flow OL 4 ea 10 3 ea NaN N gle N 8 Lw and AL are complicated quantities and we cannot put up similar equations for these Instead we shall assign them the sensitivity coefficient 1 The total standard uncertainty of Eq 13 is u L dl rti cu y cyuy 19 As shown in 4 the source model reproduces measured A weighted values with a standard uncertainty of 0 5 0 9 dB However all measurements have been carried out at roads in good condition The comparisons are based on the average from many measurement sites Some sites may give deviating results and some sites may show better agreement than the average Unless better information is available it is recommended to use the default value uw 1 0 dB As to the transfer function the variations will be large Complex weather conditions com plicated screening or large distances yield a high standard uncertainty whereas small dis tances and favourable sound propagation conditions e g during night time yield lower uncertainty It is also likely that averaging over many weather conditions will be more ac curate than looking at one specific condition Unless better information is available it is recommended to use the default value u 1 0 dB for distances up to 400 m and u 1 3 d 600 dB for distances d larger than 400 m The speed equations refer to an average speed which will show less variations than the
12. are defined as administratively fixed weather conditions as for example in the old road traffic noise method where noise levels are determined for moderate downwind The calculation for specific weather conditions is discussed in Sec tion A 4 3 Finally Nord2000 Road can be used for calculating the noise level for actual weather con ditions Actual weather conditions are short term weather conditions The purpose of cal culations for actual weather conditions is to compare with and analyze measured noise levels cf Section A 4 4 Basic Weather Conditions of Nord2000 Road Nord2000 Road is basically a short term point to point method with fixed weather condi tions The most important attribute of the atmosphere is how the sound speed varies with the height above ground The sound speed is the effective sound speed which is the combina tion of the adiabatic sound speed and the wind speed in the direction of propagation If the sound speed increases with height the result is downward refraction leading to higher A weighted noise levels compared to a non refracting atmosphere and if the sound speed decreases with height the result will be upward refraction leading to lower A weighted noise levels In Nord2000 Road the sound speed c z is a function of the height above ground z with a logarithmic part and a linear part as shown in Eq 10 de 4l Z1 ea24c 10 Zo Page 41 of 51 SINTEF Vyr where zo is the roughness length
13. by a point source in one third octave bands in every normal type of weather In the earlier models the noise levels for historical reasons were computed for different specific weather conditions The new model should allow for all types of environmental noise to be computed for the same weather conditions Sound propagation over complicated terrain should be dealt with in the new model by means of an explicit procedure that would enable all users of the model to reach at the same result in a specific case Earlier models take a skilled user to interpret an actual ter rain profile and represent it properly in the model Such subjective methods inevitably lead to unwanted variation in results obtained by different users The old Nordic prediction method was last revised in 1996 and has been in official use for almost 20 years It was based on research carried out in the 1970s Although it was revised twice the major structure has remained unchanged Nord2000 Road described in this Us er s Guide is a completely new method and in principle there are no links to the old me thod Both source data and propagation model are new The new source model distin guishes between tyre road noise and propulsion noise and the new propagation model al lows computations for a variety of weather conditions Nord2000 Road is significantly better than the old method It can handle computation in situations where the old model was not applicable it
14. national if any will decide the height of the computation point If no such tules exist use the following 1 4m outdoors according to the European directive on environmental noise 2 2 Recommended height 1 5 m above ground for use in outdoor recreational areas and in areas with one storey housing The EU Directive 2 allows the noise level at a height of 1 5 m as an additional indicator 3 Reference for indoor levels 2 m above floor level or 3 up the window whatever is highest Page 20 of 51 3 2 2 Propagation Path The attenuation of sound during propagation along the path from source to receiver de pends on the shape of the terrain and on the ground type impedance and terrain rough ness 7 The attenuation also depends on the weather conditions as described in Section 3 2 3 and in 8 Simplification of Terrain In Nord2000 Road the prediction of the sound pressure level at the receiver is based on the vertical terrain cross section from source to receiver simplified to a broken line a chain of straight line segments Figure 7 shows how such a segmented terrain may look for three categories of non flat terrain S OR S OR c Figure 7 Examples of segmented terrain a moderately non flat terrain b valley shaped terrain c terrain with a screen The way for the user to define the propagation path depends on the type of software used for the calculation It is not possible to foresee all user int
15. propagation direction 0 360 with a spacing of 10 The direction of propagation is the direction of the source seen from the receiver using the coordinate system of wind direction The direction of propagation is 0 if the source is at a position north of the receiver and 90 if the source is at a position east of the receiver Lin ear interpolation is used between the 10 values An example of a table of such statistics is given in Table 17 Meteorological statistics are presumed to be available to the user The principles for producing such data based on hourly observations or every third hour pref erably for a time period of 10 years are described in 11 The correct distribution of meteo class occurrence should be connected to the occurrence of the noise source emission The distribution should be estimated by counting the occurrence of each propagation class for each vehicle during a reference year The required data are hourly data for both traffic and meteorology Example calculation and further details can be found in 17 Page 43 of 51 Table 17 Excerpt of an example of statistical weights probability in for the period Day class A log B lin 0 12 0 04 0 0 04 0 12 1 1 00 2 1 00 3 1 00 4 1 00 5 1 00 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 1 00 22 1 00 23 1 00 24 1 00 25 1 00 0 12 0 04 0 0 04 0 12 0 10 20 30 0 0 0 0 0 0 0 0 0 2 22 0 0
16. sound propagating around the vertical edges of a finite screen In case it can do so the characteristics of the reflecting surface shall be taken into account as described be low Mapping software automatically should detect vertical surfaces which may contribute to the sound pressure level at the receiver For each reflecting surface the characteristics of the reflecting surface shall be defined by the energy reflection coefficient given in Table 13 unless more accurate data are available Page 25 of 51 l SINTEF Table 13 Examples of energy reflection coefficients pr Characteristics of reflecting surface PE Plane and acoustically hard surface concrete 1 0 stone brick wall metal sheets Non absorbent building facades with windows and 0 8 small irregularities dense wooden panels i Factory walls with 50 of the surface consisting of 04 openings installations or pipes In mapping software the number of reflections most likely is a parameter controlled by the user The number of reflections is defined as the maximum order of reflections the num ber of times the sound field is reflected This maximum order is a balance between accu racy and computation time Fifth order reflections are considered the ideal choice in strongly reflecting environment but for mapping purposes to include fifth order reflections would require too much computation time It is recommended to include up to third order
17. squares fit For a meteorologically neutral and stable atmosphere the log lin profile gives a perfect fit to the actual sound speed profile and for an unstable atmosphere the fit has been found sufficiently accurate Page 46 of 51 Appendix 5 Accuracy of Predicted Road Traffic Noise Levels There is no simple answer as to what is the prediction accuracy of Nord2000 Road There are many parameters and the uncertainty must be determined in each individual case How this can be done is outlined in the following If the quantity to be calculated is Leac which is a function of the quantities xj the principal equation becomes Leat f x 12 If each quantity has the standard uncertainty uj the combined standard uncertainty is given by U L aie Xleu 13 1 where the sensitivity coefficient c is given by me ae 14 J Assume that Leg r is determined for one vehicle category according to N L L 101g T 101g W Ly AL 101g v 10Ig 7 15 where Lw is the total sound power level ALe is the transfer function between Lw and sound exposure level Lg v is the speed T is the time and N is the number of vehicles dur ing the time 7 As shown in 4 the speed dependence of Lw if we focus on tyre road noise is approx 35 lg v and we get v N La Ly V v ALy 251g Ile 101g v 16 ref V ef Thus the sensitivity coefficient cy for speed is v OL c ape eoa 17 Ov v v
18. the prob ability of occurrence of each meteorological class To calculate the yearly average of Laen Or Lnight Statistics shall be available on the probabil ity of occurrence of each meteo class during the day evening and night Also the average air temperature and relative humidity within each meteo class shall be available together with values of other input parameters for Nord2000 Road The road authorities in each Nordic country provide such data In mapping software the statistics should be built in so that the user just has to choose the set of statistics to use country or region With less automatic software the user may have to input the statistics The procedures are described in Appendix 4 Calculation for Specific Weather The most interesting specific weather is the reference weather conditions of the old Nordic prediction method for road traffic noise These reference conditions are not particularly well defined but the Nord2000 Road parameters presumed to give the best estimate are given in Appendix 4 Another kind of specific weather represents moderate worst case propagation Recom mendations can also be found in Appendix 4 In well designed mapping software and other software the specific weather conditions can probably be defined by choosing from categories such as Weather as in the old Nordic method or Moderate worst case implying that the user does not have to key in the Nord2000 Road parameters
19. 2 2 d Hornt de Nord2000 Road s Gui User vi Authors Jergen Kragh DELTA has been the main author Hans Jonasson SP contributed on source data and accuracy Birger Plovsing DELTA contributed on propagation and weather influence Ari Sarinen VTT Svein A Storeheier and Gunnar Taraldsen SINTEF gave comments Front cover photo Carl Johan von Cappelen Layout Lene Moller DELTA Doc ref AV 1171 06 Hersholm May 2006 Contents 1 INYOdU6 d0l ic ccrsceincoinecasanienereaniensteanssdnnesnsersveiersushoesbossaeiuseousnonsersueduenensndnsesnvelunsuaiaasiwed 7 1 1 What Can Be Calculated zero ais ass A 7 1 2 What Input Data Are Needed 0 e eee cceccccessceesseceeseceseeeeseeessneeeeseeeesneesseeeesseees 8 1 3 How Can Input Data Be Obtained 00 0 sasar 9 2 Noise Levels that Can Be Computed with Nord2000 Road uu cssccsssccsssscceseee 10 2 1 Equivalent Sound Pressure Level L4eg under Specific Weather Conditions 10 2 2 Long Term Average Noise Leye leruris a ESER t 10 2 3 Contributions from Other Roads or Lanes ccececesscessseeeeseeessneeessecesneeeeseeeeeaes 11 2 4 Maximum Noise Levels isisisi anasan aan in k a tar annaa 11 3 Inp t Parameters sssssssssisisssissscssssrssssstoesists isss treri rise rS KEE EESE EEE Si o SSE ES SiN 12 dl Trafficand R ad siririn nnna a oa wae tk 12 3 1 1 Source POSIHONS sisisi ssi ason ein Aans ER s k m s ns n RANN
20. Nord2000 Road has not yet been validated and it is recommended to use class V unless accuracy is known to be improved by using class S M or L D The square root of the sum of the squared terrain height deviations from the linear segment Page 24 of 51 l SINTEF Table 12 Classification of ground roughness Roughness class Description Ground roughness Range of heights m m N Nil 0 0 25 S Small 0 25 0 5 M Medium 0 5 1 L Large 1 2 Reflections and Screens of Finite Length In order to take into account reflections from vertical surfaces propagation paths addition al to the direct path from source to receiver may be included The reflected path is from the source via the reflection point to the receiver The terrain cross section is defined along the broken propagation path in the same way as for the direct path but a correction for the efficiency of the reflector shall be included in the computation Similarly for transmission around the edges of a screen of finite length two additional propagation paths from the source via the vertical screen edge left or right to the receiver include the contribution from sound propagating around the vertical edges The terrain cross section is defined along the broken propagation path and the screening effect of the vertical edges shall be included Single receiver software normally can neither include contributions from reflecting sur faces nor
21. TA 12 3 12 Traffic Intensity er naaar aanta aaar aaa ana pan aa ada ORA ARNAN IRA APERTITA 12 3 1 3 Traffic Composition and Vehicle Parameters aiaa s 12 3 1 4 Traffic Composition aass sasar 12 315 Vehicle Speed zema S as s as sadeva asas 14 3 1 6 Traffic Distribution on Time of Day s 14 dd Ral ESIa E E E 15 3 1 8 Driving conditions 0 0 0 eescccesceeseceeseceseseeeesseeesseeeseseeessaeeesseeeesesenseeenaes 20 32 Propagation eena bs da sd ee eae 20 3 2 1 Computation Point Height isiisisiirsirsissssiissrsisrstsorsssrsssrassranstistisoti ii as 20 3 2 2 Propagation Path soinnin aana ana tapa paaa bann ara ae araara aR ea ee E E E e b ebien teaa 21 3 2 3 Weather Conditions sissi nsina aa AA EEEREN 27 4 Special Procedures ceicccccicccscscsssicccscscccscscsesscesssscececsccscesscscsecescsctecccsseceresssesecterseesrsenssee 29 4 1 Special Maximum Noise Levels 29 4 1 1 Energy Mean and Arithmetic Mean Value cececessceestseeeseeessteeesseeenes 29 4 1 2 Maximum Level Exceeded by 5 of the Vehicles a aaa 30 4 1 3 Maximum Level Exceeded more than a Certain Number of Times 30 4 2 Sound Radiated from Tunnel OpeningS cceeccesssceeseceesseeeeseeeesseeeeseeesseeeees 31 4 3 Sound Transmitted through Facades asaa ss 32 Sus 2NCCUL ACY ccececccetecccccesccsteccsssccucciedetasecss2ccdcceccscesceesoedccescdesuuedesucecsecdeccusccesscceescacesuscsesaueess 33 SL ESA S ee S S 33 5 2 Estimates of Accuracy
22. ace dense asphalt concrete water Absorbing Screen A screen is a part of the terrain cross section The properties of a sound absorbing screen are classified according to EN 1793 9 The sound absorption class can be translated into an eguivalent flow resistivity or Nord2000 Road ground class using Table 11 Page 23 of 51 Table 11 Flow resistivity class ofsound absorbing screens Screen Attenuation of Flow resistivity Recommended class no reflected sound dB kPas m2 Nord2000 Road class A0 Not tested 200 000 H Al lt 4 20 000 G A2 4 7 250 D A3 7 11 80 C A4 gt 11 40 B Ground Roughness In Nord2000 Road each segment of the terrain profile is assumed to be perfectly flat In most cases this is a reasonable assumption when a real terrain has been appropriately ap proximated by a segmented terrain However in some cases the terrain height may fluctu ate strongly along a segment These fluctuations are supposed to take place within a short range otherwise the terrain profile should be further subdivided Such fluctuation can be handled in Nord2000 Road by specifying a ground roughness unevenness The ground roughness is the rms value of the ground height fluctuations within the segment The ground roughness should be represented by one of the four classes shown in Table 12 based on an estimate of the range of height fluctuations The method for including ground roughness in
23. ata must be available for each of the periods day evening and night Information is needed on the local topography terrain shape screens buildings and ground surface types including the road surface Section 3 gives guidelines on the input data needed Computations can be made for specific weather conditions or long term averages can be computed by combining results obtained for specific conditions taking into account how often these conditions occur Page 8 of 51 1 3 How Can Input Data Be Obtained Data on the traffic can often be supplied by road authorities Care shall be taken that au thorities define vehicle categories in accordance with the definitions of the present predic tion method In case no information is available default data given in the present User s Guide may be useful Topographical information terrain profile and ground surface type is obtainable from digital maps geographical information systems Data can be imported into computation software Weather statistics are available from national road authorities Page 9 of 51 2 1 2 2 Noise Levels that Can Be Computed with Nord2000 Road Due to its ability to deal with noise levels during a variety of weather conditions Nord2000 Road is suited for computing different kinds of noise levels Equivalent Sound Pressure Level Laeg under Specific Weather Conditions The equivalent sound pressure level L4egT for the time period T can be compu
24. ate Kjell Str mmer Swedish Road Administration The project was carried out by DELTA Danish Electronics Light amp Acoustics Jorgen Kragh Birger Plovsing SINTEF Foundation for Scientific and Industrial Research at the Norwegian Institute of Technology Herold Olsen Svein Storeheier Gunnar Taraldsen SP Swedish National Testing and Research Institute Hans Jonasson Andreas Gustafsson VTT Technical Research Centre of Finland Raimo Eurasto Ari Saarinen Pekka Sipari Page 6 of 51 1 1 Introduction The present User s Guide is intended for persons wanting to run computations of road traf fic noise levels applying software working in accordance with Nord2000 Road the new Nordic method for predicting road traffic noise Software developed by SINTEF is available for type case computation For 30 different type cases the user can compute various noise metrics after having defined the traffic and weather conditions Nord2000 Road is documented in the reports listed below These reports are indispensable for developers of software for computation according to Nord2000 Road e H G Jonasson Acoustic Source Modelling of Nordic Road Vehicles SP Rapport 2006 12 Energy Technology Boras 2006 e B Plovsing and J Kragh Nord2000 Comprehensive Outdoor Sound Propagation Model Part 1 Propagation in an Atmosphere without Significant Refraction DELTA Acoustics amp Vibration Report AV 1849 00 revised Horsholm 2006 e
25. butions Index c u W 1 1 dB 4 1 1dB d lt 400m if 1 3 d 600 dB d gt 400m v 10 9 v 3 km h N 4 3 N 0 1 N vehicles 10 With the default values in Table 15 Eq 8 yields at a distance of 100 m for a speed of 70 km h the standard uncertainty U L joo 1 0 3 0 43 1 6 dB 9 The expanded uncertainty confidence interval is determined by multiplying the standard uncertainty by a coverage factor depending on the required coverage probability A cover age factor of 2 yields 95 a factor of 1 65 yields 90 and a factor of 1 3 yields 80 cov erage probability Page 34 of 51 5 3 Reguired Accuracy of Input Data The following is a guidance on the required accuracy of input data A variation in traffic flow and composition of 10 yields a 0 5 dB change and 5 yields a 0 2 dB change of Leg A standard uncertainty of vehicle speed of 3 km h yields a standard uncertainty in Leg as shown in Figure 13 Standard uncertainty dB 0 8 0 6 0 4 0 2 Speed km h 0 20 40 60 80 100 120 140 Figure 13 Standard uncertainty of L4eq resulting from a 3 km h standard uncertainty of vehicle speed A change of the distance from road of 10 yields 0 5 dB and 5 yields 0 2 dB change of L Aeg A change of small road or receiver heights of 0 2 m yields 0 5 dB 0 1 m yields 0 2 dB Of Laeq Results of computations for receiver heights smaller than 1 5 m shoul
26. cy band The temperature coefficient the change in pass by noise level caused by a change in temperature of the surface has to be determined and stated as well Page 39 of 51 Appendix 3 Main Categories and Subcategories of Vehicles Table 16 Vehicle categories applied when collecting data Normally only the three main categories are used in predictions Mai hicle length aes No Subcategories Example of vehicle types Notes yu category m la Cars incl MPV s up to 7 seats 2 axles max 4 wheels 0 5 5m Light ib Vans SUV pickup trucks RV car trailer or 2 4 axles max 2 eae with trailer i cartcaravan MPV s with 8 9 seats wheels per axle vehicles s i i or caravan not is Electric vee hybrid vehicles driven in Driven in combustion included electric mode engine mode 2a Buses 2 axles 6 wheels 7 7 12 5 Medium 2b Light trucks and heavy vans 2 axles 6 wheels 5 6 7 6 heavy 2c Medium heavy trucks 2 axles 6 wheels vehicles 2d Trolley buses 2 axles 7 7 12 5 2e Vehicles designed for extra low noise driving 2 axles 3a Buses 3 4 axles D 12 5 15 9 3b Heavy trucks 3 axles Heavy 3c Heavy trucks 4 5 axles sig vehicles 3d Heavy trucks gt 6 axles 3e Trolley buses 3 4 axles 12 5 159 3f Vehicles designed for extra low noise driving 3 4 axles oe Other heavy 4a Construction trucks partl
27. d 60 70 km h 80 10 10 85 5 10 75 10 15 kopta kookas go jolrad 3 a 35 WO i road in residential area F Residential road 30 40 km h 80 10 10 85 5 10 75 10 15 3 1 7 Road Surface Recent investigations have shown that the sound power levels of vehicles in the Nordic countries are not identical The coefficients given in 4 specifying the sound power levels of tyre road noise refer to the following reference conditions e Road surface Average of dense asphalt concrete DAC 11 and stone mastic asphalt SMA 11 with maximum aggregate size 11 mm at an age of more than 2 years but not at the end of its life span e Air temperature 20 C e Country DK FI NO and SE have an additional road surface correction For all other cases corrections have to be made and further input is required For normal asphalt road surfaces the input parameters in Nord2000 Road are 1 Country DK FI NO or SE 2 Maximum aggregate size D 3 Dense asphalt concrete DAC or stone mastic asphalt SMA 4 Air temperature Page 15 of 51 l SINTEF For these surfaces there is no correction for age unless one wants to correct for surface age less than two years The corrections AL surface given below are frequency independent cor rections valid at all vehicle speeds The correction in Figure 4 for porous surfaces is valid where studded tires are not used Correction dB Figure 2 Correction AL surface for
28. d be used with care Page 35 of 51 Page 36 of 51 Appendix 1 Source Emission Compared with the Old Model The change of vehicle noise emission introduced with Nord2000 Road is illustrated in Figure 14 and Figure 15 comparing the noise emission from Danish vehicles with that of the old model Figure 14 shows Lag at 10 m distance Figure 15 Larmax at 7 5 m distance both at 1 2 m above the ground The levels are higher in the new model particularly L rmax at high speed In the old model heavy vehicles were a mix of Category 2 and 3 with Category 2 dominating at low speed and Category 3 dominating at high speed Nord2000 Road emission data are based on measurements made since 1999 It is unknown if the higher emission values are due to changes of vehicle fleet or tyres The emission values for Finnish Norwegian and Swedish vehicles in the new method are 1 2 dB higher than for Danish vehicles because of the extensive use of harder road sur faces and larger aggregate in these countries 90 85 80 a 5 75 iu lt 70 Nord2000_DK_Cat 3 NBV_96_ Heavy 65 Nord2000_DK_Cat 2 Nord2000_DK_Cat 1 NBV_96_Light 60 20 40 60 80 100 120 140 Speed km h Figure 14 L4 at 10 m distance from a Danish vehicle as a function of vehicle speed according to the old method NBV_96 12 and the new Nord2000 Road Page 37 of 51 l SINTEF 90 85 80 a D
29. e period considered throughout a representative year Contributions from Other Roads or Lanes When the software is only able to compute the noise level from one road or lane then a manual addition of noise levels from the traffic in different lanes or on different roads can be made using Eq 2 or Figure 1 L4eg1 L4eg 2 10 Ig 10 10 2 L Aeg tot Correction dB Difference dB 0 2 4 6 8 10 Figure 1 Adding noise levels Add a correction to the highest noise level Example L4eq 53 dB L4eq 2 47 dB Difference 6 dB Correction 1 dB L4eqtot 53 1 54 dB Maximum Noise Levels Also the maximum noise level Larmax With time weighting F during the pass by of an indi vidual vehicle can be computed At present this metric is not applied to road traffic noise in Denmark and Finland In Nor way it is defined as the level exceeded by the noise from 5 of the vehicles in the actual category In Swedish regulation the requirement is that a certain value of Larmax must not be exceeded more than a certain number of times during a specified time period Proce dures for determining these maximum noise levels are described in Section 4 1 Page 11 of 51 3 1 4 Input Parameters Traffic and Road Source Positions In Nord2000 Road a vehicle is represented by noise sources situated at different heights 0 01 m 0 30 m and 0 75 m The sound power level of each source is calcula
30. erfaces of software but most likely the procedure will depend on whether the software is single receiver software or mapping software Page 21 of 51 l SINTEF Single Receiver Software It is presupposed that in single receiver software the user shall manually define the vertical terrain cross section from the road to the receiver The user may have to simplify the terrain profile into the broken line representation and assign a ground surface type and a ground roughness to each segment The user shall input parameters to define the terrain cross section as illustrated in Table 9 Each row corresponds to a point of discontinuity in the terrain profile the beginning or end point of a straight line segment Such a point is assigned a horizontal distance x a vertical height z a ground type G7 and a ground roughness GR GT and GR represent the surface properties of the line segment from the point to the next point with a higher in dex The first point is below the source and the last point below the receiver The values of x shall be in ascending order Table 9 Terrain definition for a terrain with n 1 straight line segments corresponding to n seg ment beginning end points Ground point no Distance x Height z Ground type Ground roughness 1 X1 Z GT GR 2 X2 Z2 GT GR n 1 Xn 1 Zn 1 GTa 1 GR 1 n Xi Zi Mapping Software In mapping software the vertical terrain cross sectio
31. et and M B rengier Acoustical characteristics of porous pavements a new phenomenological model Proceedings Internoise 93 641 646 Leuven 1993 B Plovsing and J Kragh Nord2000 Comprehensive Outdoor Sound Propagation Model Part 1 Propagation in an Atmosphere without Significant Refraction DELTA Akustik amp Vibration Rapport AV 1849 00 revised Horsholm 2006 B Plovsing and J Kragh Nord2000 Comprehensive Outdoor Sound Propagation Model Part 2 Propagation in an Atmosphere with Refraction DELTA Akustik amp Vibration Rapport AV 1851 00 revised Hersholm 2006 EN 1793 1 1997 Road traffic noise devices Test method for determining the acous tic performance Part 1 Intrinsic characteristics of sound absorption S A Storeheier Nord2000 Sound scattering outdoors Revised simple models SINTEF Memo 40 N0 990003 Trondheim 1999 R Eurasto Nord2000 for road traffic noise prediction Weather classes and statis tics VTT Research Report No VTT R 02530 06 Esbo 2006 Road Traffic Noise Nordic prediction method TemaNord 1996 525 Nordic Council of Ministers Copenhagen 1996 H G Jonasson and S A Storeheier Nord2000 New Nordic Prediction Method for Road Traffic Noise Version 1 0 SP Report 2001 10 Boras 2001 The source model in this report has been changed in 4 Page 50 of 51 14 EN ISO 140 5 1998 Measurement of sound insulation in buildings and of building elements Part 5 Field measurements
32. ethod distinguishes between medium heavy and heavy vehicles and introduces the number of axles of heavy vehicles as an input parameter The prediction method can handle various uncomplicated weather conditions whereas very strong or varying wind gradients as well as layered atmospheric conditions have been ex cluded By combining results from different weather conditions it is possible to calculate yearly average noise levels such as the Laen and Lnignt prescribed in the European directive on environmental noise The prediction method can handle any number and any combination of varying ground conditions with and without screens The algorithms have been limited to two screens The screens can be thin or thick with any shape The prediction method does not specifically deal with indoor noise No special guidelines or data on the sound insulation of windows or facades are given However provided that sound insulation data are known indoor sound pressure levels can be calculated from stan dard building acoustic formulae because all calculations in Nord2000 Road are carried out in one third octave bands What Input Data Are Needed To predict Lcgt the traffic intensity during the time interval T must be known as well as its speed and composition that is the percentage of different vehicle categories It is also necessary to know the type of road surface and the temperature to be used in the calcula tions To compute Laen the above mentioned d
33. ge speed should be used Table 4 Default average vehicle speed on various types of road Speed Traffic as km h Description case Cat 1 Cat 2 Cat 3 A Motorway 100 130 km h 120 90 90 B Urban motorway 90 85 85 C Main road 80 90 km h 85 75 75 D Urban road 60 70 km h 70 65 65 E Urban road 50 km h or feeder 50 50 50 road in residential area F Residential road 30 40 km h 35 35 35 Traffic Distribution on Time of Day The number of vehicles or the percentage of the traffic per category per lane when need ed during the day evening and night respectively are input parameters in Nord2000 Road Default traffic distributions are given in Table 5 Different definitions of day eve ning and night apply in the Nordic countries so the given default data cannot be valid everywhere When actual data are available these should be used For computation of Leq 24n the diurnal traffic distribution is not relevant Page 14 of 51 Table 5 Default traffic distribution on day evening and night on various types of road Distribution Distribution Distribution Traffi Cat 1 Cat 2 Cat 3 ei Description case Day Eve Night Day Eve Night Day Eve Night A Motorway 100 130 km h 80 10 10 75 10 15 70 10 20 B Urban motorway 80 10 10 75 10 15 70 10 20 C Main road 80 90 km h 80 10 10 85 5 10 80 5 15 D Urban roa
34. gives results in frequency bands and noise levels can be computed for various weather conditions and thus yearly average noise levels can be accurately computed Subsequent to the completion in 2001 of the original work on Nord2000 the source and propagation models have been adjusted in a few places Features have been taken over from the source model of the European Harmonoise project which demonstrated that it was possible to separate tyre road noise and propulsion noise and that it was good enough Page 5 of 51 to work with two point sources to describe a road vehicle This new source model has been adapted and fitted to available Nordic source data Nord2000 Road is the first official Nordic prediction method applying the new generation of methods The easiest way to get familiar with its behaviour is to exercise the type case software developed by SINTEF Commercial software is expected to be available within a short time Although great care has been taken to test the method errors or lack of clarity will un doubtedly be detected Users are encouraged to inform their national road authority The project developing Nord2000 Road was financed by NordFoU a cooperation between the Nordic road administrations The project steering committee was Lene N hr Michelsen Bent Andersen Danish Road Directorate Anders Jansson Finnish Road Directorate Baldur Gr tarsson Icelandic Road Directorate Ingunn Milford Norwegian Road Director
35. ilding the height of the highest building and the average building plan area To determine the effect of scattering in a forest data are needed on the density of trees the mean trunk diameter and the height of the forest above the ground Recommended parameter values for different kinds of scattering zones are not yet avail able but such data should become available in the future Weather Conditions Nord2000 Road can be used for calculating 1 The yearly average noise level 2 The noise level under specific weather conditions 3 The noise level corresponding to actual weather conditions Specific weather conditions are administratively fixed weather conditions such as moder ate downwind in the old road traffic noise prediction method Actual weather conditions are short term weather conditions The purpose of calculations for actual weather conditions cf Appendix 4 is not to compare with noise limits but with measured noise levels Calculation of Yearly Average Noise Levels Nord2000 Road is a point to point method taking weather conditions into account The yearly average noise level or any other long term average noise level cannot be calcu lated directly It is necessary to group the weather during the time period under considera Page 27 of 51 tion into a number of meteorological classes and to calculate the noise level for each class 11 Subsequently the calculated noise levels are combined taking into account
36. ld Nordic road traf fic noise calculation method The reference condition of this method is not particularly well defined but the following values are recommended for the best estimate e z0 025m e A 0 25 corresponding to a wind speed of 1 5 m s at 10 m above ground e B 0 corresponding to a temperature gradient of 0 C m e t 15 C giving C 340 m s e RH 70 e Cy 0 12 ms e C 0 008 Ks e oy 0 5 m s Oatdz 0 Another kind of specific weather might be useful represents moderate worst case propa gation It is recommended to use A 1 0 and B 0 04 corresponding to a wind speed of 6 m s at 10 m above ground and a temperature gradient of 0 07 C m while the rest of the Nord2000 Road parameters correspond to the above parameters of the old Nordic road traffic noise prediction method Page 45 of 51 A 4 4 Calculation for Actual Weather When using Nord2000 Road for calculating the sound pressure level for actual weather conditions the vertical sound speed profile has to be fitted the log lin profile of Eq 10 In special cases with a layered atmosphere this may not be possible and Nord2000 Road cannot be expected to work well in such cases However such cases seldom occur and in most cases the vertical wind and temperature profile can be estimated by the so called Businger Dyer profiles leading to vertical sound speed profiles which can be approximated by the log lin profile with good accuracy using least
37. maximum aggregate size Correction dB 0 0 0 5 1 0 1 5 Age years 2 0 0 1 N Figure 3 Correction AL surface for DAC or SMA surface aged less than 2 years Page 16 of 51 Correction 100 50 Age years 0 0 1 2 3 4 5 6 7 Figure 4 Correction AL surface for porous surface age the percentage of its original aB value at the new surface Valid for roads where studded tyres are not used Correction dB Air temp C 10 0 10 20 30 40 Figure 5 Correction ALsurface for air temperature It is also possible to input user defined road surfaces yielding a correction AL surface in rela tion to a defined road surface among the normal DAC and SMA surfaces with maximum aggregate size in the range 8 16 mm This correction may be different for light and heavy vehicles cf Appendix 2 For some other road surfaces typical corrections AL surface are given in Table 6 These cor rections are valid in cases where studded tyres are not used There is a need for determin ing corrections for more types of road surface Page 17 of 51 Table 6 Examples of AL surface dB from 5 Vehicle category Road surface type Identifier aa 1 2 or 3 Asphalt concrete DAC 11 0 0 Porous asphalt 0 08 less than 3 years PAC 8 5 8 3 7 Porous asphalt 0 11 less than 3 years PAC 11 3 l 3 7 Porous asphalt 0 16 less than 3 years PAC 16 2 3 Ceme
38. may be used Maximum Level Exceeded more than a Certain Number of Times The n highest maximum noise level Larmax n from N vehicles passing during a specified time period is given by L AF max L spe N rs 5 AF max n where L pma 18 the arithmetic mean value P x is the function shown in Figure 11 and s is the standard deviation If the standard deviation is unknown the values from 12 shown in Figure 10 may be used Page 30 of 51 4 2 Number of standard deviations y of vehicles with Lmax gt Lmean y standard deviations 0 10 20 30 40 50 60 70 80 90 100 Figure 11 Percentage of single events with a maximum sound pressure level exceeding by a certain number y of standard deviations the arithmetic mean of a normal distribution of maximum sound pressure levels Sound Radiated from Tunnel Openings The method to calculate the level of traffic noise originating from vehicles inside a tunnel is documented in 13 Special noise sources are positioned in the tunnel openings for ex ample as illustrated in Figure 12 The sound power levels of these sources are functions of vehicle flow traffic composition and speed as well as the sound propagation conditions inside the tunnel Input parameters are the absorption coefficient of the tunnel walls and ceiling and the tunnel dimensions Guidance on the sound absorption coefficient is given in Table 14 The directivity of the
39. ns are automatically determined from a digital terrain model and then simplified by the software The task of the user is to find and import digital terrain data or to digitize terrain contours if such data lack Ground surface types are most likely to be included by defining areas with a specified ground surface type and areas with a specified ground roughness The rest is taken care of by the software Page 22 of 51 Ground Type The ground surface type is defined by the flow resistivity of the ground surface The ground type may be specified directly by the flow resistivity or indirectly by using the classes A to H defined in Table 10 In simplified computations where it is possible only to distinguish between soft and hard ground it is recommended to use the ground types D and G respectively The road is represented by ground type G in such calculations Table 10 Classification of ground type Impedan Representative ja cel flow resistivity Description o kPas m A 12 5 Very soft snow or moss like B 31 5 Soft forest floor short dense heather like or thick moss C 80 Uncompacted loose ground turf grass loose soil D 200 Normal uncompacted ground forest floors pasture field E 500 Compacted field and gravel compacted lawns park area F 2 000 Compacted dense ground gravel road parking lot ISO 10844 asphalt G 20 000 Hard surface most normal asphalt H 200 000 Very hard and dense surf
40. nt concrete longitudinally brushed CCB lo 1 3 1 7 Cement concrete transversely brushed CCB tr 3 7 2 1 Even pavement stones PS even 3 2 Uneven pavement stones PS uneven 6 4 The road surface corrections described above are typical values and they are not necessa rily correct in a given situation The values have been simplified to be speed and fre quency independent and there will be a certain spread in data from one site to another The road surface affects the sound propagation and its acoustic impedance is needed For porous road surfaces it should be determined by measurement in each case When no bet ter information is available the default values in Table 7 may be used Page 18 of 51 E SINTEF Table 7 Default values of road surface impedances Type of road ii sure Very hard road surface 200 000 Normal road 20 000 ISO surface 2 000 Porous road Hamet model 6 Temperature affects the generation of tyre road noise and the air temperature is an input parameter For computing yearly average noise levels the mean temperature per meteo class shall be used These temperatures are available from national road authorities For information some yearly average temperatures are given in Table 8 Table 8 Yearly average temperatures Yearly average air temperature C Country Day Evening Night DK 9 8 6 FI N A N A N A NO N A N A N A SE 7 4 7
41. of airborne sound insulation of facade ele ments and facades EN ISO 10052 2004 Acoustics Field measurements of airborne and impact sound insulation and of service eguipment sound Survey method ISO Guide for the expression of uncertainty in measurement GUM G Taraldsen and H O Hygen Meteorology and Noise Emission from Road Vehicles SINTEF 90 NO050193 Trondheim 2005 Page 51 of 51
42. oise levels than the reference results The standard uncertainty of individual differences was in the order of 1 dB for distances up to 400 m Above 400 m reference results have been available for flat ground up to 1000 m where the standard uncertainty was in the or der of 2 dB The accuracy of predictions for a road for fixed weather conditions is presup posed to be better than for the point to point prediction The ability of the propagation model to predict the yearly average of Laen from a road has been validated by comparing Nord2000 Road predictions with reference results obtained by accurate calculation methods For distances up to 300 m the average differences were smaller than 0 5 dB and the standard deviation of differences smaller than 1 dB Page 33 of 51 In Appendix 5 guidelines in accordance with 16 are given for determining the uncer tainty The standard uncertainty u Lacq of a predicted equivalent noise level Leg is U L 14 4 Cy Uy y Cpu c u CyUy ig 8 The factors c are sensitivity coefficients and the uncertainty contributions u are contribu tions from index W the source noise emission index if the sound attenuation during propagation transfer function index v the vehicle speed index N the traffic intensity composition and diurnal distribution Guideline values of c and u are given in Table 15 Table 15 Guideline values of sensitivity coefficients and uncertainty contri
43. reflections Less than third order should only be used in rough estimation Mapping software should automatically include contributions from additional propagation paths around the vertical edges of a finite screen Scattering Zones With Nord2000 Road it is possible to predict the propagation effect of scattering zones which are urban areas or vegetation In urban areas the sound propagation is influenced by multiple reflections diffuse scattering by irregularities of building facades diffraction at house corners and absorption by buildings and ground surfaces In vegetation the sound propagation is influenced by reflections scattering and absorption due to trunks branches and foliage In such areas sound propagation is too complicated for a detailed calculation and it is necessary to use a statistical scattering model The effect of a scattering zone depends on the length of the ray path through the scattering zone as shown in Figure 8 and on the density and size of the scattering objects and their reflection coefficients 10 Page 26 of 51 3 2 3 diorest K lt 0 4 S K i gt R Cet ee po pind ee Os pha O S C Figure 8 Ray path through a forest To determine the effect of scattering in a housing area the following input data are needed the fraction of the plan area of all buildings to the total area of the scattering zone the sur face area the sum of walls and roof surfaces of an average bu
44. s accu racy must be judged based on results of experiments made during the method develop ment General The accuracy of Nord2000 Road is not directly comparable with that of the old model The new model has more input parameters and it is possible to calculate the noise level for more sets of conditions i e weather road surface air temperature traffic flow with 3 cate gories acceleration number of axles ground impedance while the old model predicted the noise level averaged over several of these sets of conditions It is easier to make an accu rate estimate of a mean value than of an individual value For example the standard uncer tainty of a mean value based on N independent measurements is IN times smaller than that of one individual measurement Estimates of Accuracy The source data for free flowing traffic have been calibrated against measured energy av eraged sound exposure levels and the standard uncertainty under these conditions has been found to be smaller than 1 dB The propagation model has been validated by comparing calculated attenuation values with true results of measurements or reference results obtained by accurate calculation methods Point to point validation for stationary sources showed small average differences in total A weighted levels between Nord2000 Road predictions and true results The largest dif ferences were behind screens where Nord2000 Road predicts in the order of 1 dB higher n
45. s the following is useful Leg for condition i which lasts for p of the total time is denoted Li The total Leg for the whole time interval is denoted L We get L 101g p 10 p 10 p 10 23 However as 2 p 1 these coefficients are not independent Instead we write Eq 23 in the form n l L f p10 p10 kn 10 4 Sp 24 i l For cpi we get OL 10 16 a 101g e 10 25 Li is determined with the standard uncertainty up and p with the standard uncertainty upi The standard uncertainty u of L is given by 2 2 n l1 ur gt i l OL 2L L aL 2 26 Op i pi Page 49 of 51 References 1 Good Practice Guide for Strategic Noise Mapping and the Production of Associated Data on Noise Exposure European Commission Working Group Assessment of Ex posure to Noise January 2006 Directive 2002 49 EC of 25 June 2002 of the European parliament and of the coun cil on the assessment and management of environmental noise L 189 12 Official Journal of the European Communities 18 7 2002 SINTEF Type case computation software To be published Trondheim 2006 H Jonasson Acoustic Source Modelling of Nordic Road Vehicles SP Rapport 2006 12 Energy Technology Boras 2006 P A Morgan P M Nelson and H Steven Integrated assessment of noise reduction measures in the road transport sector PR SE 652 03 ETD FIF 20020051 from TRL amp RWT V J F Ham
46. speed of individual vehicles and in many cases uy may be quite small e g 3 km h On the other hand a calculation for one specific rush hour may imply large uncertainty Some days the traffic may flow well while it is more or less standstill on other days Unless bet ter information is available it is recommended to use the default value uy 3 km h The uncertainty due to traffic flow variation could vary If it is a yearly measured average the uncertainty will be small On the other hand we may have to estimate the flow of heavy Category 3 vehicles based on traffic data several years old containing only the total number of Category 2 and Category 3 vehicles Unless better information is available it is recommended to use the default value un 0 1 V vehicles Eq 17 is valid for one category of vehicles We could assume that all categories have the same uncertainty However if the uncertainties are different between the categories we have to add them up We then get L 101g 10 102 10 20 Page 48 of 51 where L L2 and L are the calculated Leq for the three categories of vehicles The sensitivity coefficient cr is then given by aa W 10 In 10 0 1 10 uL 04 4102 4102 5107 21 The standard uncertainties are given by Eq 13 applied on all vehicle categories and the total uncertainty is then given by Uly YC Cu Cu X 22 In case we want to add results from different weather condition
47. tandard deviation of fluctuations in the temperature gradient oa accounts for fluc tuation in temperature gradient in excess of what is already included in the turbulence strength It is recommended to use a value of zero unless other information is available Together with the air temperature the relative humidity is used to predict the attenuation due to air absorption The value is normally available in standard weather data Calculation of Yearly Average of Noise Levels The procedure described in this section is used to calculate the yearly average of Laen and Lpignt defined in Section 2 2 Laen is based on Leg for the day evening and night time while Laight iS Lacq for the night time To calculate the yearly average a number of meteorological classes meteo classes have been defined to represent all types of weather occurring through the year A format has been defined with 25 meteo classes where each class is defined by a representative value of A and B 11 When determining the sound speed profile by Eq 10 a value of zo 0 025 m is used To calculate the yearly average of Laen and Lnight statistics shall be available giving the probability of occurrence of each meteo class Also the average air temperature and rela tive humidity within each meteo class shall be available for use in noise emission as well as noise attenuation computation The statistics vary with the direction of propagation and should be available in the range of
48. ted for spe cific weather conditions such as for example slightly downwind Long Term Average Noise Level Long term average noise levels are determined by computing the noise levels under the specific conditions occurring during the time period considered and then combining them into the average value According to the European directive on environmental noise 2 the yearly average values Of Laen and Lnign are mandatory indicators to be applied to strategic noise mapping The A weighted long term average day evening night noise level Lien is defined as L 10 night 7 10 1 Lay Levening 5 ev 1 Lan 10 lg31T 10 710 where Ta Te and T are the durations of the day evening and night respectively h and L ays Levening and Light are the A weighted long term average noise levels for the day eve ning and night period respectively The day evening and night periods shall be defined by each Member State Some defini tions are given in Table 1 oe of day evening and night for use when calculating Laen in the Nordic countries Denmark DK Finland FI Norway NO Sweden SE Day 07 19 07 19 07 19 06 18 Evening 19 22 19 22 19 23 18 22 Night 22 07 22 07 23 07 22 06 Page 10 of 51 2 3 2 4 l SINTEF The noise level for each of the time periods shall be averaged over all meteorological variations and sound emission variations that occur during the tim
49. ted using eguations with input parameters selected by the user The sound power contributions are derived from tyre road noise and propulsion noise Heavy vehicles with high exhaust have an extra source at 3 5 m height The horizontal position of all sources is presupposed to be at 1 m from the vehicle centre line in the direction to the receiver Traffic Intensity The input parameter is the total number of vehicles per lane per unit of time Traffic Composition and Vehicle Parameters If more reliable data are not available the default parameter values given below may be applied The default traffic composition vehicle speed and traffic distribution are based on but not identical with available data from the Nordic countries Analyses have shown that the variation between data from different countries only leads to minor differences in computed noise levels taking the expected accuracy into consideration Traffic Composition The percentage of each category of vehicle or the number of vehicles per category per unit time is an input parameter in Nord2000 Road The vehicle categories in Nord2000 Road are summarized in Table 2 Category 1 includes cars and delivery vans The categories in the table are operational definitions often used in traffic counts and noise prediction When collecting data on vehicle noise emission the classification in Table 16 in Appendix 3 should be used Page 12 of 51 Table 2 Short form characteri
50. y off road use vehicles 4b Agr tractors machines dumper trucks tanks Mostly 7 7 12 5 Two 5a Mopeds scooters Includes also 3 wheel wheelers 5b Motorcycles motorcycles D 2 3 4 5 3 4 axles on car amp trailer or car amp caravan Also 4 wheel trucks if it is evident that they are gt 3 5 tons Hybrid vehicles driven in combustion engine mode Classify as either la or 1b If high exhaust identify this in the test report Categorize as 3b 3c 3d or 4a For example some delivery trucks are designed for extra low noise meeting more stringent stan dards than the current EU limiting levels combined with a driving mode called Whisper mode making it possible to drive in a residential area with much lower noise emission than for a conven tional delivery truck Trucks and buses especially designed in accordance with these ideas are counted in this category Page 40 of 51 A 4 1 Appendix 4 Weather Conditions Nord2000 Road is basically a point to point method with weather conditions as described in Section A 4 1 The yearly average noise level or any other long term noise level can not be calculated directly by Nord2000 Road but if the weather is grouped into a number of meteorological classes the yearly average can be determined as described in Section A 4 2 Nord2000 Road can also be used for calculating the noise level for specific weather condi tions Specific weather conditions
51. zation of the categories of vehicles in Nord2000 Road Vehicle Short Maximum Vehicle category description gross weight length Characteristics no kg m Additional input parameters 1 Light 3 500 lt 5 5 Studded tyres Wet surfaces 2 Medium 3 500 12 000 5 6 12 5 2 axles 6 wheels 3 or more axles 3 Heavy gt 12 000 gt 12 5 Additional input parameter Average no of axles When more reliable data are not available the default values of the percentage heavy vehi cles in Table 3 may be applied These data are not representative of roads with special traf fic such as heavy transport of wood in parts of Finland or Sweden Table 3 Default traffic composition on various types of road Composition Traffic MOE Description case Cat 1 Cat 2 Cat 3 A Motorway 100 130 km h 85 5 10 B Urban motorway 85 5 10 C Main road 80 90 km h 85 10 5 D Urban road 60 70 km h 90 5 5 E Urban road 50 km h or feeder 95 5 0 road in residential area F Residential road 30 40 km h 100 0 0 Page 13 of 51 3 1 5 Vehicle Speed The average vehicle speed per category is an input parameter in Nord2000 Road Default average speeds are given in Table 4 These data were used in the type case computations 3 to limit the number of cases and they do not necessarily represent the actual average speed on an individual road in a certain class When known the actual avera
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