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Test cases for control of Nord2000
2 Test Cases for a Straight Road
For a straight road 62 test cases have been developed to test nearly all aspects of the Nord2000 Road Traffic Model.
The horizontal distances in the terrain profile (x-coordinates) perpendicular to the road are measured from the centre line of the road. The road has two lanes, each 5 m wide, and the vehicles are driving in
the middle of the nearest lane, and there is no traffic in the far lane.
The vehicles are category-1 vehicles (cars and vans) except in test cases 17 and 18 where vehicles are category-2 vehicles (dual-axle heavy vehicles), and category-3 vehicles (multi-axle heavy vehicles),
respectively. In all cases a speed of 80 km/h has been used. The axle width is 1.5 m for category 1 and 2.5 m for categories 2 and 3.
The total length of the road is in all cases 20 times the shortest horizontal distance dmin between the centre line of the road and the receiver point which is placed in the middle. dmin is in all test cases 100 m
except in case 16 where dmin is 1000 m. The road is divided into 101 equidistantly placed source points. The distance between the source points is therefore 20 m in all cases except in case 16 where the
distance is 200 m.
The results of the 62 cases are given in the Excel spreadsheet "TestStraightRoad.xls" with one worksheet for each test case. An example of a sheet is shown in Appendix A (Test Case No. 1). The main
results are:
- The sound exposure level LAE and the corresponding spectrum LE (unweighted) for the pass-by of a single vehicle
- The 24-hour equivalent A-weighted sound pressure level LAeq,24h and the corresponding spectrum Leq,24h (unweighted) for 10,000 vehicles per 24 hours
- The A-weighted maximum level LAmax
- The propagation effect dL (for information, not required in the test process). The propagation effect is the difference between LE and the "free-field" value of LE (disregarding ground and screening effect
as well as air absorption).
Besides the results, the sheet contains for each test case the model propagation parameters and the terrain profile given by the distance X from the road centre line perpendicular to the road, the height Z of
the terrain, the ground flow resistivity, and the terrain roughness.
The 62 test cases for a straight road can be grouped with respect to the terrain shape as shown in Table 1.
Group 1 (flat terrain) contains test cases with variation in ground impedances, meteorological conditions and vehicle category. The remaining groups represent 11 different geometrical propagation cases, and
for each group 4 calculations have been made: downwind, no wind, and upwind, all with a receiver height 1.5 m, and no wind with a receiver height of 4 m.
In group 12 (forest) additional parameters are needed to define the scattering zone which is not included in the information given in Appendix A. The scattering zone parameters are defined in Table 2.
Table 1: Test cases divided into 12 groups.
| Group |
Terrain description |
Test cases nos. |
| 1 |
Flat terrain |
1-18 |
| 2 |
Flat mixed terrain (varying impedances) |
21-24 |
| 3 |
Elevated road, roughness class N |
31-34 |
| 4 |
Elevated road, roughness class M |
41-44 |
| 5 |
Valley |
51-54 |
| 6 |
Valley with a lake in the middle |
61-64 |
| 7 |
Thin hard screen on flat ground |
71-74 |
| 8 |
Thick hard screen on flat ground |
81-84 |
| 9 |
Two screens on flat ground |
91-94 |
| 10 |
Non-flat valley-shaped terrain |
101-104 |
| 11 |
Non-flat hill-shaped terrain |
111-114 |
| 12 |
Forest, flat terrain |
121-124 |
Table 2: Definition of forest parameters in test cases 121-124.
| Parameter |
Value |
| x-start |
10 m |
| x-end |
80 m |
| NQ |
0.075 m-1 |
| H |
10 m |
| α, |
0.1 |
| Kp |
1.25 |
| Atrunc |
0.15 m |
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Version 1.0 July 2005, © Danish Environmental Protection Agency
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