| With the improvement of economic level and the increase of the infrastructure investment, China’s highway mileage of operation period has been increasing year by year, the total mileage reached 4.5 million by the end of 2015. While the total mileages of highway increased, relevant environmental problems in our society became increasingly serious, and particularly the areas of acoustical sensitivity near the road have been polluted widely by the traffic noise. Therefore, it is important to predict traffic noise of highway in operating period accurately during the highway feasibility study and design stage.Traffic noise prediction model given in the Environmental Impact Assessment on Highway Construction Project is widely used in practical projects. However, there are some deviations when we apply this model to traffic flows at low speed. Besides, the traffic flow is considered as the linear acoustic source occurred in the equivalent lanes in that model, but it is inaccurate to predict the acoustic emissions on the both sides of the road on account of the widening of road and the uneven distribution of traffic volume. Given that, in this paper, the vehicle noise emission model was decomposed into the power unit noise component and the rolling noise component to modify the traffic noise prediction model in specification. And a study was carried about the model adjustment in the case of uneven distribution of traffic flow. These studies can provide theoretical basis for highway traffic noise prediction.On the basic of analysis and summary of domestic and foreign literatures about traffic noise, the power unit noise model was developed, and the rolling noise model was introduced. Furthermore, the vehicle noise emission models are developed to improve the original models at low speed stage. The differences were presented between the new models and those was revealed in specification, so vehicle noise emission model was modified. The difference between the traffic noise emission of one side and the other side for a highway section is the function of traffic flow distribution coefficient and speed under the different road-cross section forms. Traffic noise prediction model was modified using this function.Finally, the case includes two highway sections in Harbin was conducted in order to validate each model result. A comparison with existing theoretical models and measurements reveals some of the strength of the adjusted models when they were applied under some certain conditions. |
