Research On Vehicle Emission In Urban Road Network

With the growing amount of vehicles, the burden of traffic network is becoming increasingly heavier, which influences the transport demand of residence and brings about a serious environment issue. HC, CO, and NO_x are the main causes of photochemical pollution and haze. A quantitative traffic emission assessment can provide scientific evidence for traffic network emission assessment, traffic atmosphere environment assessment and traffic regulation. However, most of the existing researches try to study the network emission at the macro level, which hardly reflects the operational state of vehicles. Studying the traffic network emission form the micro level is of great importance on both theory and practice.Based on former achievement, this paper analyzes and compares the numerical theories and the application extent of some most commonly-used emission models. MOVES and TSIS are selected to be tools for emission assessment and computational estimation. First of all, the traffic network emission model of Qingyuan city was established through the microscopic traffic simulation software TSIS, the outputs of which are the emission amount of some HC,CO and NO_x,the traffic volume and the average speed. Meanwhile, using MOVES, the new emission model software developed by EPA, to calculate the amount of automobile exhaust emissions separately on the basis of two methods, average speeds and volumes(AVG) and second-by-second operating mode distributions(OPMODE).the data of traffic volume and average speed used in MOVES are extracted from TSIS, which shows the organic combination of dynamic traffic operational characteristics and advanced emission models. Then, the results of automobile exhaust emissions from MOVES and T ISIS are specifically compared and analyzed. Finally, an emission forecasting method, based on TSIS simulation and MOVES model, is proposed and the emission quantit y of Qingyuan city in 2016 is estimated at the end of this paper.The calculation and prediction results show that:(1) When MOVES used for small network, the calculation results respectively from the TSIS simulation output and the operating condition of distribution are very close, with an error of 1.2~7.9%;(2) When MOVES used for the sections of highway, the calculation results error of the CO and HC emissions are within 10% while the calculation results error of NO_x is about 13.0~17.0%.(3) When the traffic network is not saturated, pollutant emissions and traffic have good linear relationship, TSIS simulation software and MOVES can both be used to predict the vehicle emissions.