Impact of traffic parameters prediction on the accuracy of noise modelling

The prediction models allow calculating the traffic road noise that is expected in the future on the designed roads. One of the most important data inputs to these models are: the number of vehicles, speed and traffic composition. Inaccuracies in the predictions of traffic parameters have a significant impact on the results of noise modelling and its precision. Currently, there are not many publications explaining their impact on the results of acoustic calculations. Just a few studies show results based only on theoretical analyses. To assess this impact, the results of predictions made between 2005 and 2013 were analysed, and then 'in situ' measurements of real traffic parameters were made. The research covered 133 road sections located in Poland. In the next step, the results of the forecast and real data were compared to each other and, using the NMPB-Routes-96, RLS-90, CNOSSOS-EU and PK models, the impact of the traffic parameters prediction on the results of the noise calculations for the designed roads was determined. It was found that these predictions have a significant impact on the inaccuracies of the noise modelling conducted for designed roads, which can also affect the parameters of the necessary noise mitigation measures.