Study On The Impact Of High-Speed Rail On Coupling Relationship Of Land Transportation Accessibility And Urbanization Level

Strengthening regional connectivity is the key step for China’s urbanization development from extensive expansion to high-quality development.Therefore,urbanization development has a more urgent demand for fast and convenient transportation.High-speed rail has the characteristics of high speed and large traffic volume,which can bring huge flow of people,logistics and information.Compared with air transportation,ship transportation and road transportation,it has a more profound impact on the development of urbanization.As the role of high-speed rail construction in urbanization is controversial,it needs to be inspected and tested based on China’s national conditions.In this context,exploring the coupling and coordination relationship between traffic and urbanization level of Chengdu-Chongqing urban agglomeration,it is helpful to understand the positive or negative effect of high-speed rail construction on urbanization of urban agglomeration,and can provide reference for the realization of the coordinated development mode of "high-speed rail + urban agglomeration".This study takes Chengdu-Chongqing urban agglomeration as an example,to set three scenarios: no high-speed rail,current high-speed rail and planning high-speed rail under the condition of with or without high-speed rail traffic.Firstly,with average travel time and weighted average travel time as input indexes,economic potential and daily accessibility as output indexes,the comprehensive accessibility index of Chengdu-Chongqing urban agglomeration is calculated by using Super-DEA model,and the traffic accessibility under three scenarios of urban agglomeration is analyzed.Then,Construct an urbanization level evaluation system from five aspects: population urbanization,economic urbanization,social urbanization,land urbanization and urban-rural coordinated development.And use the AHP-entropy method to comprehensive integration,describes the spatial and temporal distribution characteristics of urbanization development level in cities(districts)and counties of urban agglomeration in 2009 and 2018.Finally,with the help of coupling coordination degree model and spatial lag model,it explores the coupling relationship and interaction between traffic accessibility and urbanization level of Chengdu-Chongqing urban agglomeration under three scenarios.The main conclusions are as follows:(1)Traffic accessibility evaluation of Chengdu-Chongqing urban agglomeration:Single accessibility index,from the traditional mode of transportation to the emergence of high-speed rail,the accessibility level of districts and counties in Chengdu-Chongqing urban agglomeration has been improved to varying degrees,especially the districts and counties through high-speed rail and their surrounding areas.With the formation of high-speed rail network,the traffic accessibility of urban agglomeration has gradually formed a multi center distribution pattern.According to the comprehensive accessibility index,the average comprehensive accessibility values of the three scenarios are 0.66,0.71,0.82,and the proportion of areas with traffic level higher than the average is 50.45%,47.75%,62.16%.Under the effect of high-speed rail strengthening the radiation of core cities,the high value area of accessibility level of urban agglomeration spreads from Chengdu-Chongqing development axis to Chengdu Mianyang Leshan urban belt and riverside urban belt.(2)Evaluation of urbanization development quality of Chengdu-Chongqing urban agglomeration: According to the weight,the subsystems are ranked in order:population urbanization > social urbanization > economic urbanization > land urbanization > coordinated development of urban and rural areas.In terms of time,the overall urbanization level of each subsystem shows an upward trend from 2009 to2018.In terms of economic urbanization,Chengdu-Chongqing high-speed rail,Xi’an-Chengdu passenger dedicated line and other areas along the high-speed rail develop rapidly,and the ranking of surrounding areas rises by 1-3 with the core cities.In terms of social urbanization,the areas with an increase rate of more than 22% are mainly distributed around the core cities or along the high-speed rail.There is a "fault" in the development level of land urbanization,and the land development level of core cities is much higher than that of other cities and counties.In the coordinated development of urban and rural areas,the gap between Deyang City and Mianyang City has expanded significantly.From the spatial point of view,the coordinated development level of urban and rural areas takes Chengdu as the single core distribution pattern,and the other four subsystems take the main city of Chongqing and Chengdu as the double core distribution pattern.Population urbanization has a "polarization trickle-down effect" in space,and the development level of districts and counties around the main city of Chongqing has been greatly improved.Economic urbanization presents the distribution pattern of "double core high,middle and edge low",with the characteristics of spatial proximity.The development level of social urbanization is similar to that of economic urbanization.The appearance of "siphon effect" results in the decline of the development level of the area along the main axis of Chengdu-Chongqing development,resulting in the "central collapse".(3)Evaluation of the comprehensive urbanization development quality of Chengdu-Chongqing urban agglomeration: In terms of time,the average value of the comprehensive urbanization development index of Chengdu-Chongqing urban agglomeration increased from 0.4266 to 0.4845,and the regional difference was narrowing.63.88% of the cities and counties in the urban agglomerations have a growth rate between 10% and 20%,and the cities along the high-speed rail have a large rise.In terms of space,the spatial distribution characteristics of urbanization are the same as those of sub-system.The urban belt along the Yangtze River has developed into a high-level area with the help of the core cities under the high-speed rail connection.Spatial relevance,the urbanization level of Chengdu-Chongqing urban agglomeration has spatial agglomeration on the whole,showing a core edge structure locally,and the polarization phenomenon of hot and sub hot spots is more prominent.The cold spots in the Northeast are affected by "distance attenuation",and the correlation is weak.(4)The coupling relationship between traffic accessibility and urbanization level of Chengdu-Chongqing urban agglomeration: In terms of coupling degree,the overall coupling degree of traffic accessibility and urbanization level of Chengdu-Chongqing urban agglomeration under the three scenarios is relatively high.In terms of coordination degree,the coordination degree of the areas along the high-speed rail has improved significantly,and the coordination degree of urban agglomeration has increased from low coordination to high coordination,forming a decreasing distribution pattern with Chengdu-Chongqing as the center to the surrounding circle.The coordination degree has strong spatial agglomeration on the whole and weak local agglomeration.In terms of coupling and coordination,the spatial distribution patterns of no high-speed rail and current high-speed rail scenarios are similar,showing a zonal distribution pattern with high coupling and high coordination as the center and spreading to the southwest and northeast in turn,showing a high coordinated development under the planning high-speed rail scenario.Under the three scenarios,the proportion of coupling coordination type in areas with higher level and above is44.44%,47.22%,63.89%,which indicates that high-speed rail promotes the coordinated development of transportation and urbanization.(5)Analysis on the influencing factors of traffic accessibility and urbanization level of Chengdu-Chongqing urban agglomeration: The impact of urbanization factors on transportation development,urbanization has a significant impact on the transportation development under the construction of high-speed rail in the future,in which the per capita GDP,the proportion of the output value of the secondary and tertiary industries,the population density,and the average GDP of each region have a greater contribution.The impact of traffic factors on the development of urbanization,the road network density has the greatest effect on the development of urbanization,and the contribution of different types of road density to its development is also different.The regression of traffic proximity and the negative coefficient of the distance between adjacent core cities indicate that the closer the distance to the main traffic lines and core cities,the more conducive to the development of urbanization.