Analysis of most important environment and traffic effects on emission of Lmax in Tehran- Mashhad highway

This paper examines the traffic noise in Golestan National Park road that has passed through the Golestan National Park. The increasing number of vehicles that travel in the country’s highways has led to an increase in the noise level. Therefore، traffic is considered a main source of noise pollution in this area. In this road to determine factors affecting on noise modeling was performed. Because the models are useful tools to identify changes in current and future traffic conditions. At first، for evaluation of noise and recording independent variables، sampling stations were selected using a Systematic-Random method in 76 points at various distances from the road. In each sampling point environmental variables، geometry of road surface and traffic conditions was measured for 15 minutes during 8 am to 8 pm. then modeling was performed among 18 independent variables and one dependent variable using stepwise regression. To verify the model، data of 26 stations not used in the previous modeling effort were randomly selected. In this way، the best multivariable regression based on correlation coefficient (R) and coefficient of determination (R2) was achieved. The result of modeling showed that the Lmax model have 6 variables including distance from the road، slope of plot، temperature، relative humidity، number and speed of high vehicles that have the greatest impact on sound propagation. The regression equation were 68% respectively. Therefore this model was as the final model. Thus، one model was obtained for a maximum sound level (Lmax (1h)) in the Golestan National Park road.