Sound levels forecasting for city-centers Part IV. Vehicles stream parameters influence on sound level distribution within a canyon street

To control an environmental noise the simulation programs are the best tools. Especially when efficiency of administration means such as introduction of limits of vehicles speed and heavy vehicles rate flows are evaluated. Here is used the computer simulation program PROP5 that allows predicting the time-average sound level within an urban system. A roadway as a noise source is represented by a sum of the sound exposures due to individual vehicles pass-by. The multi-lanes roadway and different representations of equivalent point sources for various classes of vehicles are allowed. Propagation throughout an urban system contains multi-reflections from the walls and single and double diffraction at their wedges. In the paper, the PROP5 program is used to present the sound level along façades of buildings creating a canyon street. The road of J lanes passed by two classes of vehicles: light and heavy ones is assumed. The consequence of a change in vehicle average speed treated as an independent parameter is analyzed. The vehicles speeds straight affect the sound level and by speed dependence of the equivalent sources power levels and spectra. Indirectly the change in vehicle speed limit can affect the vehicle flow rate by the interrelations of traffic. By use of calculation examples, the range of possible changes in the sound level is presented.