Study On Noise Reduction Effect Of Sound Barrier And Noise Prediction Of City Expressway

In recent years, urban traffic network represented by rapid rail transit and urban expressway has been developed rapidly. On the one hand, the development can meet the increasing demand of city transportation, on the other hand led to urban pollution increased. Characterized by high speed traffic, heavy traffic and increasing proportion of big cars in the morning and evening, the quality of the urban expressway is not well.The traffic noise census showed a rather bad environmental quality surrounding around the inner ring expressway in Chongqing. Nowadays, noise pollution has becomed the hotspot and keystone of the environmental complaint. Sound barrier engineering is the main ways and means to control the impact of traffic noise.Research and analysis about the effect of the noise barrier have the lack of single measuring point, less test time, unrepresentativeness and universality.The main topic of this article is firstly through measuring a large amount of data on typical sections to analysis the environmental quality of urban expressway and study the character of the sound environmental in the shadow owning one piece of the noise barrier. Secondly, to study the effect of the noise barrier and analysis the differences for the actual noise reduction with the theoretical insertion loss. What’s more, the prediction models of the noise have been revised.The main contents of this paper are as follows:① The sound environment of the urban expressway surrounding about is poor in the daytime while a few of the points outside the shadow is exceeding. It is very serious at night and the noise level is rather higher than the limit value of standard.② The actual noise reduction is between the 1.5 and 6.5d B, whatever, the barrier has proven ineffectual or even counter-productive for the points while beyond the shadow. The test results showed the predicted insertion loss larger than the measured value as a result of the gap which causes according to the sound transmission. The predicted area of the shadow is smaller than the actual one. Real data computation shows that the effect of the noise barrier correlates to the vehicle very well.③ Due to the sound barrier, different heights of the noise sources are reflected and smoothed to a height of 0.5 meters. Furthermore, the noise sources are simplified as a single source.④ The predicted values achieved from the noise prediction model is better thanthe field test. Its previous difference between the predicted values and the actual one is-4~4 d B, and the other one is-7~7d B.