Research Of Vehicle Exhaust Emission And Dispersion Modeling At Urban Signal Intersection Based On The IVE Model

Vehicle exhaust emission has become one of the main sources of urban air pollution,and the signal intersection is the hotspot of urban vehicle exhaust emission,so it has extensive theoretical guiding significance for vehicle exhaust emission control and reduction strategies to learn vehicle exhaust emissions in actual driving conditions and its dispersion characteristics to analysis the influence of traffic emission on air quality at urban intersection.In this paper,Hangzhou was taken as a case,and the IVE vehicle exhaust emission model was locally corrected and the CAL3 QHC dispersion model for intersection was modified to learn vehicle exhaust emissions in actual driving conditions and its dispersion characteristics at urban intersection.And the influence of signal timing optimization strategy based on exhaust emissions on the micro-environment air quality was analyzed.In this paper,the main research work is as follows:(1)The IVE emission model was used as the basic research method in this paper after in-depth analysis of the current widely used vehicle emission factor models considering its easy localized correction.The basic principle and characteristics of the IVE model was studied and the correction method based on the emission rates of the VSP bin was selected to modify the default basic emission factors in the IVE model in view of the regional differences when it was actually used;(2)The vehicle exhaust pollutant emission characteristics was learned by test bench experiment method to get the CO and NOx emission rates of each VSP bin in the IVE model and their idle emission rates.On the basis,the default basic emission factors of IVE model was corrected.The feasibility of the correction method used in this paper was verified by comparing the measured with modeling results before and after correction;(3)A field investigation was carried out at a real intersection in Hangzhou to learn exhaust dispersion character,and the IVE model after local correction and CAL3 QHC dispersion model was used to model the character of vehicle exhaust emission and dispersion at the intersection.The modeling results were compared with the measured ones to estimate the model performance.A novel piecewise finite line source method was proposed to modify the deficiency of CAL3 QHC model.The results showed that the modified model had a better performance in urban intersection dispersion modeling,and it could be applied to model vehicle exhaust concentration and air quality assessment near intersection.(4)A signal timing optimal model was designed to minimize vehicle exhaust CO emission volume based on the vehicle emission characters at urban signal intersection with the traffic data of a typical intersection in Hangzhou.And the genetic algorithm(GA)was used to solve the model.The impact of the signal timing strategy on exhaust emission and air pollutant concentration near the intersection was studied with the corrected IVE emission model and the modified CAL3 QHC dispersion model.The results showed that the signal timing optimization strategy based on vehicle exhaust emissions and average delay was one of the effective ways to improve the traffic environment and reduce traffic air pollution without changing intersection configuration.