Study On Risk Assessment And Traffic Organization Optimization Of Motor Vehicle Pollution In Population-Intensive Area

With the rapid growth of the vehicle population in China,problems related to traffic congestion,exhaust emissions and other issues have become increasingly important.Pollutants such as CO,SO₂,NO₂,PM2.5 and PM10 from motor vehicle exhaust have been identified as significant causes of air pollution and haze in cities and can have serious effects on the environment and health of city residents.Studying the spatial and temporal emission characteristics of motor vehicle pollutants and their effect on the health of residents in urban areas is therefore important and can assist policy makers in the development and identification of control measures to reduce their negative effects.The densely populated areas include public gathering places,outpatient buildings,teaching buildings,kindergartens,and so on.This thesis outlines the results of pollutant collection experiments collected from crowded urban areas,and presents a set of statistical analyses of the experiment data.This thesis also proposes a vehicle emission and diffusion model,which can be used to quantify the risk of motor vehicle pollutants to the surrounding populations.This thesis then proposes suggestions for reducing pollution based on regional traffic characteristics.This research provides the basis for urban traffic environment governance.The specific research content carried out in this thesis is as follows:Firstly,Yujiatou Primary School in the City of Wuhan and its surrounding areas were selected areas the study area.Monitoring points were established at the school's side entrance and main entrance as well as at the intersection of Tieji Road and Heping Avenue.A Cairpol instrument and a JCF-3A dust monitor were used to monitor the concentration of motor vehicle exhaust pollutants,including CO,NO₂,SO₂,PM10 and PM2.5.Data collection was conducted between the hours of7:45-8:00 am and 16:15-16:30 pm.Traffic counts from the surrounding areas was also collected using a video system.Information on vehicle types?small car,medium car,large car,bus?,traffic flow?left turn,right turn,and through movement counts?,vehicle speed,intersection signal timing and other data were all extracted from the recorded videos.Secondly,statistical analyses were conducted to analyze the spatial-temporal distribution characteristics of each pollutant.The results of the analyses showed that the CO concentration was higher in the afternoon than in the morning at all three monitoring points.The concentration of SO₂ was 85?g/m³ for the whole day.There was no significant difference between the concentrations of SO₂ at the morning and afternoon.The concentrations of PM10 and PM2.5 value was also lower at the intersection of Tieji Road and Heping Avenue than at side entrance and main entrance gate.The daily average intake threshold for respiratory exposure for children was obtained from the"Ambient Air Quality Standards?GB 3095-2012?"and"Chinese Population Exposure Parameters Handbook?Children's Section?"and compared to the values obtained from the monitoring equipment.The results of the comparison showed that the concentration of the gaseous pollutants?CO and SO₂?was slightly below the associated threshold values.However,the concentrations of PM10 and PM2.5 were both higher than the threshold specified in the national standard.Consideration of the health of children in this area therefore requires the measures to be implemented,including traffic control,improved signal timing,one-way or detour,in order to reduce vehicle pollution.Finally,AnyLogic software was used to create a traffic simulation model of the roadways surrounding Yujiatou primary school.The measured traffic flow was used as the input,and the signal timing of the intersection was optimized.Based on this scheme,several optimization schemes were established and comparedand obtained the optimal solution.A vehicle pollution emission model and a Gaussian diffusion formula were used to calculate the minimum vehicle pollution of the concentration value and daily average intake.The prohibition of random parking can also reduce the concentration of pollutants,and the simulation was compared with the optimized signal timing plan.The results of the simulation showed that the average daily intakes of CO,SO₂,PM10,and PM2.5 were 6.7×10^-3 mg/?kg·d?,1.75×10^-4 mg/?kg·d?,1.65×10^-4 mg/?kg·d?and 1.60×10-4 mg/?kg·d?respectively after the signal timing was optimized.When compared to the values obtained from signal timing plan before,CO,SO₂,PM10 and PM2.5 was found to be reduced by 34.31%,60.59%,81.41%,and 64.04%respectively,and all concentration was found to be lower than the daily intake threshold of respiratory exposure.The prohibition of uncontrolled parking programs is more effective but it is inconvenient to implement.Therefore,optimizing signal timing can reduce pollutant concentration more quickly and efficiently.