Research On Inventory And Visualization Of On-road Vehicles On Major Roads In A City

In recent years,the number of urban automobiles has been increasing continuously,which not only brings convenience to people’s lives,but also seriously affects the quality of ambient air.It has become a major contributor to environmental air pollution in some large and medium-sized cities.Considering the severe situation and harmfulness of motor vehicle pollution,it has become an imminent urban environmental problem to find out the characteristics and distribution of urban motor vehicle pollution and further strengthen the supervision and prevention of motor vehicle pollution.Taking Nankai district of Tianjin as an example,this study selected some main roads as research objects,and based on the methods introduced in the guide,investigated the basic data needed for the preparation of motor vehicle emission inventory,and established a mathematical calculation model of vehicle emission pollutants based on road traffic flow,and realized the time-space distribution and dynamic visualization of vehicle pollutants based on road network.The main research contents and conclusions are as follows:(1)By means of investigation,literature inquiry and crawler,the data of motor vehicle ownership in Tianjin up to the end of 2015,the fuel quality in target year,hourly traffic flow information and weather data of some main roads in the study area were obtained.The data obtained were collated and analyzed.(2)The actual road emission test of three typical types of vehicle based on PEMS was carried out,and the emission factors under actual driving conditions were obtained.Through comparison,the difference between theoretical calculation value and actual value of vehicle emission factor is discussed.It is found that the actual emission intensity of vehicle on the road is larger than theoretical calculation value on the whole,and the difference is more prominent in the low-speed section.(3)A mathematical model for calculating road vehicle emission pollutants was established.Combined with the data of hourly traffic flow and weather,the hourly CO,HC and NO_x emissions of the vehicles in each section were calculated.The contribution rate characteristics of pollutants are discussed from three aspects:fuel type,emission stage and vehicle type.At the same time,the impact of eliminating the yellow label vehicle on the overall emission of the road network was simulated.The results show that the average daily emissions of CO,HC and NO_x are 15.52,1.81 and 7.32 tons.Among them,gasoline vehicle is the main contributor of CO and HC,diesel vehicle is the main contributor of NO_x,and vehicles in national III have the largest share of pollutants.The elimination of yellow standard cars can reduce CO,HC and NO_x by 2.5%,6.0%and 8.4%.(4)Based on the platform of GIS,a time-space allocation method of pollutant emission from on-road motor vehicles was developed in order to get a more intuitive understanding of urban road emissions.The characteristics and distribution regularities of pollutant emission from motor vehicles in the region were studied by this method.The emission of vehicle pollutants in road network has a strong time-varying trend,which is similar to the trend of traffic flow.There is a significant difference between the emission of vehicle pollutants in peak periods and that in ordinary periods.