Research on Numerical Simulation of Pollutant Dispersion at Expressway TollPlazas Based on Multi-influencing Factors

摘要

Currently, expressway toll stations in China generally use loading-based tollcollection. Because vehicles spend long time either stationary oraccelerating/decelerating in low gears, air quality is particularly susceptible to theaccumulation of vehicle-emitted pollutants at toll plazas. In this workthree-dimensional computational fluid dynamics (CFD) simulations were carried outto analyze the pollutant concentration distribution in the vicinity of tollbooths.Several influencing factors including wind velocity, wind direction and topographyof toll plazas were considered. A simulation instance of the Wuzhuang toll plaza inHefei-Nanjing expressway was performed. The simulation results show that theincrease in wind speed facilitates the pollutant dispersion. There is higherconcentration of pollutant as the angle between the direction of wind and trafficbecomes larger. The existence of retaining walls impedes the pollutant dispersion.However, the slope of retaining walls has little influence on the variation of pollutantconcentration.