Research On Spatial Diffusion And Emission Reduction Strategy Of Motor Vehicle Pollutants On Capital Ring Expressway

With the development of economy and the increase of travel demand,the traffic volume of expressway has been in a growing trend,Congestion in holidays has become the norm,and the air pollution caused by vehicle exhaust emissions is becoming more and more serious.Beijing is surrounded by the Capital Ring Expressway,which passes through Langfang,Baoding,Zhangjiakou,Chengde and other areas.The traffic volume is large and the proportion of freight is high.The topography along the line is different,which has a great impact on the air quality of the surrounding cities or towns.Based on the MOVES and CALPUFF models,combined with the traffic volume,geographical and meteorological data along the line,this thesis establishes the emission model-diffusion model-scenario model of motor vehicles on the Capital Ring Expressway,quantitatively studies the emission characteristics and diffusion spatial distribution of motor vehicles on the Capital Ring Expressway,and evaluates the emission reduction effect and reduction effect of pollutant concentration under different emission reduction scenarios,and put forward the expressway emission reduction suggestions..Firstly,according to the actual data of the Capital Ring Expressway,the MOVES model is localized,and the vehicle emission factors of Baoding,Zhangjiakou,Chengde and Tangshan are simulated,taking 2018 as the base year,the pollutant emission inventory of motor vehicles on Capital Ring Expressway was established.It is found that the average daily emission of pollutants from motor vehicles on the Capital Ring Expressway in 2018 is 48.49 t,of which CO,NOx,HC,PM₁₀ and PM_2.5accounted for74.4%,21.8%,3.0%,0.5%and 0.4%respectively.The contribution rate of small buses and large trucks is the largest;the emission of motor vehicles in different regions is ranked from large to small:Baoding>Zhangjiakou>Tangshan>Chengde;CO and HC mainly come from gasoline vehicles,while NOx,PM₁₀ and PM_2.5 mainly come from diesel vehicles.The comparative study shows that the total amount of pollutant emission from motor vehicles on the Capital Ring Expressway calculated according to the Technical Guide for the Compilation of Air Pollutant Emission Inventory of Road Motor Vehicles（Trial Implementation）is about 2.5 times of the results of MOVES model.The MOVES model simulates the emission factors of each vehicle type based on the actual local climate,Motor vehicle activity level data,etc,which can better reflect the real situation.Secondly,the geographical and meteorological data of the surrounding areas of the Capital Ring Expressway were collected.The CALPUFF model was used to simulate the pollutant concentration of the motor vehicles on the Capital Ring Expressway in July 2018.The Arc GIS software was used to obtain the concentration spatial distribution map,with the resolution of 4 km×4 km.It is found that the average concentrations of CO,NOx,CH₄,PM₁₀ and PM_2.5are 6.5 mg/m³,2.3 mg/m³,0.27mg/m³,0.055 mg/m³ and 0.056 mg/m³ respectively.The pollutants gradually spread to both sides along the direction of the highway,and the concentration on both sides of the highway is not uniform.The farther away from the highway,the smaller the concentration distribution of pollutants.Due to the influence of traffic sources,topography,meteorology and other comprehensive factors,the degree of pollution along the Capital Ring Expressway varies greatly,showing the characteristics of higher in the South than in the north,and higher in the east than in the west.Finally,based on emission model and diffusion model,scenario analysis method is used to quantitatively evaluate the emission reduction effect under five scenarios.The results show that the comprehensive situation has a good effect on pollutant emission reduction and concentration control.From the perspective of urban and rural areas,land use and ecological environment along the line,the thesis puts forward suggestions on emission reduction of Capital Ring Expressway:actively promote new energy vehicles on expressways,change passenger and freight transportation mode on expressways,strengthen traffic management and supervision of motor vehicles on expressways,and strengthen vegetation protection in rural areas and ecological areas along the line.This study provides a theoretical basis and policy basis for air pollution control,so as to promote the green development of expressway.