Accessibility Of Public Service Facilities Under The Influence Of Rail Transit

With the rapid development of urbanization in China,the imbalance of public service facilities become more and more serious.Under the background of the transformation and reform of urban transportation system,the rapid construction and development of rail transit bring an opportunity for the layout adjustment of public service facilities.It is a great significance to study the accessibility of public service facilities under the influence of rail transit for optimizing the layout and configuration of public service facilities and improving the service level of urban rail transit.Taking Nanjing downtown as an example,this paper use the spatial analysis,accessibility measurement model of public service facilities and mathematical statistics to study the time accessibility,resource accessibility,resource supply and demand matching and resource allocation equality of public service facilities under the influence of rail transit.And this paper analyze the differences of time accessibility under different travel modes,which provide reference for the layout and configuration of public service facilities and the long-term planning of rail transit construction.The main research results are as follows:(1)The weighted optimal time route under real-time traffic conditions is obtained by using Internet map service,and the travel time cost from residential area to four types of public service facilities(business center,hospital,high school,scenic spot)is calculated based on the time cost calculation method of "complete travel chain".The results show that: compared with the traditional time cost calculation method based on network analysis and grid analysis,the time cost calculation method based on "complete travel chain" is more accurate,which can reflect the actual traffic conditions and reduce the data collection and updating work of road network model.(2)Combined with the nearest neighbor distance method and cumulative opportunity cost method,this paper measures the time accessibility of public service facilities under different travel modes in the city,analyze the temporal and spatial distribution characteristics of the accessibility of public service facilities and the impact of rail transit on the time accessibility of public service facilities.The results show that: different travel modes form different spatial distribution patterns of time accessibility.The access of rail transit to public transport network improves the time accessibility of public service facilities,and the time accessibility of medium and long distance travel is more obvious than that of short distance travel.(3)Based on the time accessibility difference measurement index of travel mode,the time accessibility difference under different travel modes is measured.The results show that: the time accessibility differences of travel modes show obvious directional characteristics of metro lines.After rail transit is connected to the public transport network,After the rail transit is connected to the public transport network,the dependence of residents on cars and bicycles is reduced,especially in the medium and long distance travel and the areas along the subway.(4)Based on fine-grained population data,an optimized two-step mobile search method is proposed,and the distance attenuation parameters and search threshold parameters are analyzed experimentally.Then,taking the medical facilities as an example,this paper measures the time accessibility and resource accessibility of the medical facilities under the bus mode and subway mode in different travel periods(morning peak,evening peak and evening peak).The results show that: the accessibility of the two modes is affected by road traffic congestion,and the impact of public transport mode is greater.Rail transit improves the time accessibility and resource accessibility of medical facilities.In different travel periods,the order of rail transit on accessibility is: morning peak period > evening peak period > flat peak period.(5)Combined with Z-score standardization method,Lorentz curve and Gini coefficient,this paper studies the impact of rail transit access to public transport network on resource supply and demand matching and resource allocation equality.The results show that: the rail transit access to the public transport network improves the matching degree of supply and demand of medical facilities resources,and improves the medical demand of residents in low accessibility and low population density areas.At the same time,rail transit access to the public transport network has improved the equality of medical facilities resource allocation,but the improved medical facilities resource allocation is still in a highly unequal state.The relevant departments should increase medical resources or add or optimize subway lines to improve the equality of medical facility resource allocation in the future.