Measuring Green Accessibility Based On Taxi Trajectory Data Mining

With the increasingly serious situation of global air pollution and greenhouse effect,low-carbon city construction has been paid more and more attention in the world.At present,in the research on low-carbon city planning,there is still a lack of effective evaluation indicators and description method for the convenience degree of residents in low-carbon life.Accessibility,as an important concept in urban planning,is widely used in urban traffic planning,urban public facilities location distribution and equity evaluation,etc.It is one of the goals of urban planning to make urban residents enjoy higher accessibility.In the current accessibility research,time is often used as the accessibility metrics.The use of vehicle emissions as a constraint resource will provide a new perspective for understanding urban accessibility from the perspective of low-carbon travel and has important practical significance in the social context of building low-carbon cities.Until now,the research on accessibility with emission as the explicit constraint dimension is relatively lacking,and in the existing research,the average speed of road network is adopted to calculate road segment emissions,ignoring the impact of vehicle driving behavior on emissions.In this paper,based on taxi GPS big data,the actual driving cycle distribution of vehicles on the road section is extracted,and the research on green accessibility of emission constraints is carried out,mainly including the following contents:(1)Two green accessibility models with emission as the metric are proposed.One is the calculation model of the number of accessible facilities under a given emission threshold,and the other is the calculation model of the emission cost under a given number of accessible facilities.The models provide quantitative evaluation metric and description method for understanding the urban accessibility in the context of low-carbon travel,and expands the research perspective of urban accessibility.(2)A method of implementation of the green accessibility model based on GPS trajectory data is proposed.Aiming at the problem that the actual driving behavior of vehicles is ignored when calculating emissions in the existing emission-constrained accessibility research,the taxi GPS big data is used to extract the actual driving cycle distribution of vehicles on the urban road network,and the calculation method of the optimal emission path is proposed based on the vehicle emission model,which is applied to the calculation of green accessibility.(3)The green accessibility models are used to make an empirical study in wuhan city.Firstly,the spatial and temporal distribution and equity of green accessibility in wuhan are analyzed.Then,the traditional time-constrained accessibility evaluation method is used to analyze the accessibility of wuhan city,and the results are compared with the distribution characteristics of green accessibility,so as to understand the similarities and differences of accessibility from two perspectives.The results show that both the green accessibility and the traditional time-constrained accessibility are affected by land use and transportation network factors,and the distribution characteristics of accessibility under the two measurement methods are similar on the whole,but different in the details.Compared with the time-constrained accessibility model,the green accessibility model provides more analytical dimensions for understanding urban accessibility.In the social context of building low-carbon cities,traveling by vehicles with smaller engine size can bring about higher urban green accessibility.