Research On The Influence Of Urban Built Environment On Traffic Emissions Based On Taxi GPS Data

With the increase in car ownership,China’s transportation industry has become the third largest source of greenhouse gas emissions,second only to industry and construction,and is considered the most difficult part to achieve transportation emission reduction.Urban transportation systems become more complex in the context of rapid urbanization and motorization,besides residents’activities are increasingly restricted by the built environment,which brings major challenges to the sustainable development of the city,so the active intervention of the urban built environment to reduce traffic emissions has become one of the focus of urban management.There are many types of elements involved in the urban built environment,also there are large differences of built environment in spatial regions.Therefore,the research on the relationship between traffic emissions and the built environment cannot be generalized,differentiated and targeted exploration and analysis are needed.Under the goals of"carbon peak"and"carbon neutrality",the impact of the built environment in different spatial regions on traffic emission reduction will be the focus of research.In order to enhance the effect of traffic emission reduction,this article will explore the association of urban built environment and traffic emissions as well as their spatial heterogeneity effects.In this paper a study based on multi-source data:taxi GPS data,POI,road network and land use data.On the basis of summarizing the results of the completion of the built environmental impact study on transport emissions at home and abroad,the area within the third ring road of Xi’an is first taken as the research area to analyze taxi operating characteristics including:trip volume,speed,travel time,hot spots,etc.;The areas with more travel hotspots:Lianhu District,Xincheng District,Beilin District,and Yanta District are used as the follow-up traffic emission study area,and taxi trajectory points are used to reconstruct its trajectory,then the traffic emissions are calculated and its temporal and spatial distribution characteristics are analyzed;Subsequently,the traffic districts are divided,and the emissions and built environment indicators of the traffic districts are incorporated into the OLS regression model to screen for significant variables and conduct impact analysis.,then build a gradient boosting decision tree model to explore the marginal effects of built environment indicators on traffic emissions;Finally,based on the spatial analysis function of GIS,the spatial autocorrelation analysis of the traffic emissions of the traffic district is carried out to study its spatial dependence;Then a geographically weighted regression model is constructed to quantify the spatial heterogeneity effect of the urban built environment’s impact on traffic emissions,and a traffic reduction strategy is proposed.The research results show that:(1)Taxi trip volume has regularity in time distribution.The verage running speed is 20km/h,and the passengers mostly travel in short distances of 10min-20min.Travel hotspots are mainly distributed around the Zhonglou,Gulou,Xiaozhai,Xi’an Railway Station,followed by colleges and universities,hospitals,and Gaoxin zones;(2)The temporal and spatial distribution characteristics of traffic emissions are significant,there are obvious emission peak periods and emission hot spots in road sections and areas;(3)Population density and public transportation accessibility do not have a significant impact on traffic emissions in the study area.The degree of impact of significant built environment indicators on traffic emissions in descending order is:residential density>road network density>density of educational and cultural places>land use mix degree>employment density>subway station density.There is a marginal effect between built environment and traffic emissions.Control other indicators unchanged,when only one variable is changed:when the land use mix degree is between 0.4 and 0.8 or the employment density is between 0 and 125/km~2 or the subway station density is between 1.5 and 2.5/km~2,it has a significant suppression of traffic emissions effect;(4)The impact of built environmental indicators on traffic emissions has obvious spatial location differences.the regression coefficient varies greatly,the impact of the built environment on traffic emissions under different spatial locations has a promoting or inhibiting effect.In addition,the density of houses can promote traffic emissions in the whole study areas,but the impact intensity of different spatial locations is different.