Study On Noise Characteristics Of Urban Road And Construction Of Noise Map Information System

With the process of urbanization and the improvement of road network construction, the traffic noise pollution is increasing obviously. Currently, the research of the urban road traffic noise mainly focus on monitoring, forecasting and model validation. However, the research of the actual road noise is mainly based on short-time measurement data, and lacking of long-term monitoring and observations.The specific roads within the area of 11 square kilometers in Ningbo city were choosed as research objects in this study. Based on a large number of experimental observation data, we analyzed the relationships between urban road noise and traffic flow, and verified the applicability of various predicting models. Furthermore, we tried to establish urban noise map system, and achieve the noise map of experimental area. The main results are as follows:(1) Based on the analysis of long-term and continuous observational data, the traffic noise on an ideal straight road with smooth traffic is characterized and the relationships of pressure parameters of traffic noise and traffic flow are developed. It has been found out that there is significant correlation between the urban road noise and traffic flow; road traffic noise energy mainly concentrates in the low frequency component less than 250 Hz, the peak appears at 63 Hz; the energy distribution reduces from the component higher than 1000 Hz.(2) Based on the automatic monitoring and statistical methods, the main source, main effecting factors and the spectrum characteristics of urban road noise were analyzed. The main conclusions are as follows:during smooth transportation, away from complex traffic conditions such as intersections, a logarithmic relationship exists between the noise level and the equivalent traffic flow, the fitting results can be applied to similar road noise forecasting. The use of noise evaluation index, such as L50, L90 and L95, helps to reflect the traffic noise characteristics and the close relationship with traffic flow more completely. The low frequency component of traffic noise is closely related to traffic flow, while the high frequency component of traffic noise less affect the environment because of its quick attenuation.(3) Analyzing the accuracy of the current widely used noise models from both sides of theoretical analysis and experimental verification, the result shows that:in general, the results with these noise predicting models consistent relatively well with the site-measuring data, which can be used in urban road traffic noise prediction on the basis of certain adjustment; model RLS90 and model FHWA perform relatively well in case of high large-vehicle percentage and small traffic flow. With the traffic flow increasing, model NMPB and model CRTN perform better. It can be speculated that the base emission data of heavy vehicles is much lower than the domestic actual situation with the model NMPB and model CRTN.As a result, the outcomes of these two models are usually much lower than the actual situation in case of large-vehicle percentage increases.(4) Based on the study of urban road noise characteristics and analysis of noise model, we try to construct a city noise map information system and draw out the noise map of the experimental area.