| With increasing urbanization and mobilization,the rail transit system has been established as the backbone of modern urban public transportation.High-density rail transport networks have a significant influence on urban spatial structure in the face of growing urbanization.Reasonable integration of the two can effectively improve the efficiency of urban resource allocation and provide new opportunities for the realization of urban sustainable development.Recently,transit-oriented development(TOD)has been widely advocated by cities around the world as a sustainable urban development model that effectively integrates land use and transportation systems.However,each city has its own unique development intensity,urban environment,and development pattern,thus TOD implementation strategies need to be constructed and evaluated according to local conditions.Therefore,it is necessary to clarify the interactive relationship between rail transit and urban spatial structure,quantitatively evaluate the current development status of station areas,and analyze the role of TOD indicators in the relationship between urban vitality and happiness,which is of great significance to optimizing the rail transit system to guide green travel and build a livable city.Based on fine-grained spatio-temporal data,this study analyzes the interactive relationship between rail transit and urban space and its performance from macro and micro perspectives.Multiple methods and concepts,such as complex network theory,flow space,and TOD,are employed in transportation planning,urban planning,GIS,and other related fields.This study reveals the synergistic level of rail transit system and urban spatial structure and their relationship with urban vitality and satisfaction.The main findings are shown as follows:(1)Analysis and modeling of the spatiotemporal evolution of urban rail transit systems using complex networks.Based on the complex network and spatial distribution characteristics,the negative exponential function growth model of rail transit network nodes is constructed to quantitatively describe the spatial distribution and spatio-temporal evolution characteristics of the rail transit network.Taking the development of Shanghai rail transit as a case study,the universal law of coupling development between urban spatial structure and rail transit is revealed.The results indicate that the current Shanghai rail transit system shows the characteristics of a small world.The cross-section coefficient of the negative exponential growth model represents the change of the density gradient of the rail transit physical network in urban space.From the change in the coefficient,the Shanghai rail transit network grows from a high compact spatial form to a flat form,and connects more and more with the city’s sub-center,suburbs,and other parts of the city.The change of passenger flow weighted network coefficient shows that the passenger flow of Shanghai rail transit system tends to gather in the urban area on weekdays,while the travel activities of urban residents are more dispersed on weekends.With the development of rail transit,the evolution of degree centrality of passenger flow weighted network reflects the suburban diffusion characteristics.(2)A node-place-network model was proposed to evaluate the level of collaborative development among land use,public transport,and travel demand.The OD network passenger flow characteristics are innovatively introduced into the traditional node-place-network model,and an extended node-place-network model is proposed to evaluate the synergistic development level between rail transit,built environment and travel demand.The effectiveness of the model was verified at 286 metro station areas in Shanghai,China.The results show that TOD has been implemented in Shanghai,but there is a mismatch between the travel demand of rail transit stations and the surrounding environment.This is largely due to the complex relationship between transport systems and travel patterns.Secondly,the differences between the classification results are compared and analyzed to find out the potential rail transit stations that need to be improved.Thirdly,the synergy between travel characteristics of individual stations and environmental development is quantitatively evaluated by the carrying pressure index to provide guidance for the development of polycentric cities.Finally,based on the comparative analysis of cross-section data,the change characteristics of the coordinated level of the station area in Shanghai are analyzed.It is found there is an upward trend among the passenger flow,land use and transportation of the station area.(3)Synergy-based TOD performance analysis from the social dimension.Based on social media data and Tencent location data,social performance indicators are constructed from two perspectives,which are city vitality and satisfaction.To evaluate the different relative importance of factors,the complex interaction between TOD factors and the nonlinear impact on the social performance of the site are explored by using Extreme Gradient Boosting(XGBoost)and the SHAP explainable model.The results show that the spatial distribution of the two dimensions of social performance in Shanghai has significant spatial autocorrelation characteristics.Moreover,the nonlinear relationship between the influencing factors and social vitality and satisfaction is significant.The goodness of fit of the social vitality model is greater than that of the satisfaction model,which indicates that the traffic and land use distribution in the station area were more closely related to the number of people’s activities than the subjective emotion.TOD factors have a nonlinear relationship with social performance and exhibit a threshold phenomenon.This study extands the quantitative method of the synergistic relationship between rail transit and urban spatial development,enriches the TOD social performance research from the humanistic perspective,and is of great value to the exploration of rail transit planning and practice suitable for Chin a’s national conditions. |
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