Street Canyon And Vehicle Exhaust Pollution Diffusion Simulation Study

The city Chongqing, lies in the mountainous country with special geography and climate, many high and dense buildings, and the narrow street. All these are extremely disadvantageous to the dilution of transportation waste gas. The number of the motor mobile in the Chongqing city is increasing with the high speed of 24℅ in these years. These have been 380 thousand of motor vehicles in the urban until the end of the year 2006. It brings prosperity to the economy, and it also contributes much to the air pollution in Chongqing city. According to the results of much research, vehicular exhaust directly leads to the deterioration of air quality in streets.It's a complicated process for the vehicular exhaust to disperse in street canyon. This process may be affected by many factors such as vehicle flow, meteorological factors and street geometry and so on. Zhongshansan road is seleceted as the objects of this study. Emphasis is put on how the meteorological factors and street geometry affect the dispersion process of the vehicular pollutants in street.NOX concentration is stimulant object, STREET-SRI and OSPM models are selected to simulate the dispersion process of the vehicular exhausts in the streets according to the characteristics of the meteorological conditions in Chongqing and street geometry in Zhongshansan road. Using NOX concentration data measured by the author Zhongshansan road, the modeled values are compared with the measured values. It is concluded that OSPM models is more capable of simulating the dispersion and forecasting the concentration of vehicle exhaust in streets of Chongqing, OSPM modeled values have good relativity(R=0.881).The author uses the OSPM model simulating the NOX in the sidewalk of the Zhongshansan raod in various wind speed, wind direction, vehicle flow and street geometry, And use the OSPM model calculates the vehicle flow in the street at various wind speed, wind direction and street geometry in order to make the NOX in the sidewalk. We analyse the causation of vehicular exhaust of the Chongqing, also make some suggestions of controlling vehicular exhaust. The results of this study have obvious scientific value to Chongqing, and consultant to city planning, traffic management and vehicular exhaust fathering.