Environmental traffic noise modelling of Dhanbad township area - A mathematical based approach

Environmental noise is an undesirable by product of industrialization and urbanization where this unwanted sound makes a significant damage to human beings viz. can cause hypertension, hearing loss, sleep disturbances and also has a hazardous impact on our environment. The present study was undertaken to analyse the spatial characteristics of road traffic noise at varying intervals viz. morning (6-9 Am) & (9 Am-12 Pm), afternoon (2-5 Pm), evening (5-8 Pm) & night (8-11 Pm) hours at different road networks of Dhanbad town by using Sound Level Meter and also noise contour maps was produced by GIS to visualize the monitoring locations. The monitored results indicated that the highest and lowest average noise levels (LAeq) were 87.2 dB(A) and 71.3 dB(A) during evening and night respectively. This study also aims to examine the accuracy of the CRTN model in predicting traffic noise in Dhanbad township from the traffic variables. The results show that the performance of the CRTN model in morning (9-12 Pm) for predicting roadside traffic noise levels, with an coefficient of determination (R2) of 0.819 and a mean difference of +0.8 dB(A) between the measured and predicted values. Predicted traffic noise of evening (5-8 Pm) & night hours (8-11 Pm) is less accurate as with coefficient of determination (R2) of the 45° line is less than 0.7. It is due to type of passing vehicles, the mean traffic speed and its fluctuating, and the type of road surface are the most important reasons for low accuracy in predicting level. The suggested road traffic noise model can be used as a decision support tool for predicting equivalent sound pressure level index in the cities like Dhanbad.