Research On The Impact Of Rail Transit Development On Urban Air Quality Heterogeneity

The impact of rail transit development on urban air quality is mainly achieved by influencing residents' travel modes,and this unavoidable will involve the choice of residents' travel modes.In theory,the opening of rail transit will replace traditional non-green transportation methods,generate traffic substitution effects to improve air quality,and may create more non-green transportation demand,resulting in traffic creation effects and increasing urban air pollution.By combing the existing researches,most of the research is based on the two assumptions of traffic creation effect and traffic substitution effect.On the basis of synthesizing the existing literature,this paper explains the relative price changes of transportation modes brought about by the development of rail transit by constructing the Slutsky equation of urban traffic demand,and causes the dual effects of traffic substitution and traffic creation.In-depth analysis of the conditions of traffic creation effect and traffic substitution effect hypothesis and the mechanism of rail transit impact on urban air quality heterogeneity,and propose relevant policy recommendations.In terms of empirical analysis,this paper uses the breakpoint regression design to verify the daily air quality and hourly data,the relevant climate variable daily and hourly data and other macro panel data of 21 cities in the newly opened rail transit line between 2014 and 2017 in China.The relationship between the development of Chinese rail transit and the change of urban air quality,and based on this,based on the number of urban permanent residents and the average monthly housing price of the city,the urban classification is carried out,and the intrinsic influence mechanism is also carried out in the heterogeneity analysis.In-depth study.Then,this paper selects two typical case cities in the sample city,and further verifies and expands the relevant conclusions from the aspects of air pollutant types and pollution time.The empirical research shows that the influence of rail transit on the development of urban air quality in China cannot be generalized.The traffic effect and its impact on the city depend on the comprehensive effect of traffic creation effect and traffic substitution effect.(1)From a national perspective,the traffic creation effect of rail transit on urban air quality is greater than that of traffic substitution.Under the effect of traffic creation,the overall air quality index of sample cities is increased and air pollution is intensified.For the first-class cities with a permanent population of more than 9 million,the main traffic effects are consistent with the national level conclusions;for the second-class cities with a resident population of 7-9 million,neither the traffic creation effect nor the traffic substitution effect Significant;for the third-class cities with a permanent population of less than 7 million,the traffic substitution effect is greater than the traffic creation effect.Under the effect of the traffic substitution effect,the air quality index of such cities decreases and the air quality improves.(2)For cities with high non-green vehicles in all types of cities,the traffic substitution effect is greater than the traffic creation effect,reflecting the substitution effect of rail transit on traditional non-green vehicles.Among various non-green vehicles,the development of rail transit has the most significant impact on private cars,which also shows that the effect of traffic in cities is closely related to the choice of residents' travel modes.(3)For cities with higher monthly average housing prices in all types of cities,the traffic creation effect is greater than the traffic substitution effect.The increase in housing prices brought about by the development of rail transit leads to an increase in the price ratio between green transportation and non-green transportation.The demand for green transportation is reduced,and the demand for non-green transportation is increasing,resulting in increased traffic pollution.(4)For the concentration of various pollutants,the traffic creation effect and traffic substitution effect produced by rail transit are most closely related to the particulate matter(PM2.5,PM10)and hydrocarbon concentration,and both types of pollutants are motor vehicles.The main substances in the emissions further verify that the traffic effects of rail transit are related to the frequency of residents' use of motor vehicles.(5)For the pollution period,the traffic substitution effect of rail transit during the peak daily travel time is greater than that during the off-peak period,which proves the influence of rail transit on the choice of residents' daily travel modes,which proves the robustness of the research conclusions in this paper.The literature has paid less attention to the traffic creation effect,and overestimated the environmental benefits of the subway opening.The main contribution of this paper compared with the previous literature is(1)combining the macro level with the micro level of the typical case city.The simultaneous existence of traffic creation effect and traffic substitution effect is verified from different angles.(2)In terms of data selection,the data used in this paper are the daily data of all air monitoring stations in the city and hourly data of various pollutant concentrations.The data volume is large and the regression results are more accurate and reliable.(3)Based on the breakpoint regression model,this paper analyzes urban differences from the perspective of urban heterogeneity,and conducts various types of robustness tests to ensure the comprehensiveness and effectiveness of the empirical results.