Environmental Project No. 1022 – Test cases for control of Nord2000

Test cases for control of Nord2000

4 Test Cases for a City Street

Four test cases have been included for city streets. Three of the calculation points (Positions 1-3) are placed in a street with the same traffic flow, but with different contributions from reflections. The last calculation point (Position 4) is placed in a street parallel to the street with the traffic flow, but without traffic itself. The calculation points and the buildings important to the sound propagation are shown in Figure 2.

Figure 2: Plan view of city area.

Figure 2: Plan view of city area

The buildings have flat roofs, and the height of the buildings is 12 m. The coordinates of the buildings, the road centre line, and the calculation points can be found in the Excel spreadsheet file containing the calculation results.

Calculations have been carried out for an energy reflection coefficient of the facades of both 1 and 0.7. The receiver points are placed at the facades (at a distance of 0 m from the surface) at heights above the road surface of 1.5, 4, and 8 m. The sound pressure level at the receiver point has been calculated disregarding the reflection of the facades at the receiver ("free-field" SPL), but including all first and second order reflections from other facades. If the software to be tested cannot ignore the reflection of the facade, the calculated result of this software has to be corrected for the effect of the reflection (-6 dB or whatever reflection effect is applied in the software to be tested).

The road has two lanes, each 6 m wide, and the vehicles are driving in the middle of each lane. The number of vehicles is 10,000 per day, and the traffic is distributed equally on the two lanes. All vehicles are light vehicles (category-1). The speed is 50 km/h, and the axle width of the vehicles is 1.5. The distance between the source points along the lane is 2 m for receiver Positions 1-3 and 20 m for receiver Position 4.

The propagation parameters are the same as used in the "Curved Road" group described in Section 3 except that a wind speed of zero is assumed (u = 0 m/s).

The results of the 4 cases are given in the Excel spreadsheet "TestCityStreet.xls" with one worksheet for each test case. An example of a sheet is shown in Appendix C (Receiver Position 1).