A comparison between different traffic noise forecasting methods and experimental data.

Considering the growing importance of noise pollution produced by urban road traffic, a correct assessment of its characteristics become extremely relevant. According to European Noise Directive 2002/49/EC the environmental noise indicators, based on equivalent sound pressure levels, can be measured, or preferably calculated, through computation methods. For this reason the accuracy of the results obtained must be carefully evaluated before using them for the realization of strategic noise maps. Several computational methods, based on different parametric algorithms, are available for the calculation of equivalent sound pressure levels. In this paper is presented a comparison between the results given from two of the most popular forecasting codes, the French NMPB and the English CTRN, and experimental data. Moreover the noise levels produced have been studied by using statistical descriptors to better analyze traffic characteristics, in order to show if and how the forecasting methods fit real situations. The measures have been conducted in different traffic scenarios (close to a traffic roundabout and near to a semaphore crossroad) and some other analysis have been made to highlight the possibility to use the above mentioned methods in medium size cities and in metropolitan ones.