Spatial Accessibility Measurement And Optimization Of Multi-Modal Public Transport Networks In Chongqing

Along with the accelerated urbanisation in China,the number of motor vehicles owned by residents is increasing significantly and the limited urban space is no longer sufficient to meet the travel needs of residents.Problems such as road congestion and environmental degradation have negatively affected people’s standard of living.Public transport has the characteristics of high carrying capacity,high operational efficiency and low resource consumption,and with the modernisation of cities,the development of green public transport also brings the advantages of energy saving and emission reduction,so vigorously developing public transport travel and increasing the public transport share of residents is an effective way to alleviate the serious traffic problems in China.In this paper,we study the accessibility of public transport networks,construct a accessibility measurement model for multi-modal public transport networks in modern cities,and propose layout optimisation strategies for multi-modal public transport networks based on accessibility.In this paper,we first understand the basic theories of accessibility,summarise the basic concepts,main characteristics and influencing factors of accessibility,analyse the advantages,disadvantages and applicability of traditional accessibility measurement models,and define accessibility of multi-modal bus networks as "the opportunity and convenience for travellers to use a multi-modal bus network to get from the point of travel to the destination within a limited urban space.The accessibility of a multimodal bus network is defined as "the opportunity and convenience that a traveller has in a limited urban space to use the network to get from the point of travel to the destination".By layering multi-modal networks and analysing the interactions between conventional and rail transport,it is suggested that accessibility models should be constructed with the goal of promoting cohesion and reducing competition.In this paper,the accessibility of multi-modal transit networks is quantified in three areas: station accessibility,OD accessibility and line accessibility.Firstly,the station accessibility model is a combination of the traditional gravity model and the utility model,and the evaluation indicators are station weighted attraction and generalised travel cost,where the generalised travel cost includes the travel time on the bus network,the traveler’s time to enter and exit the bus network using the slow-moving transport system and the transfer time,and also incorporates the factors of congestion discount factor,economic monetary cost and transfer penalty factor;the OD accessibility model is In the process of passenger allocation,the shortest path is first found based on Dijkstra’s algorithm,the penalty method is used to generate the set of effective paths,and finally the SUE model is solved using the SRAM algorithm;and the line network accessibility model is the average value of the generalised travel cost spent by travellers using the bus network for one trip.The thesis then combines existing bus network optimisation methods and proposes a multi-modal bus network layout optimisation strategy based on accessibility.The objective is to improve the overall accessibility of the bus network and the operating profit of the bus company.A two-layer optimisation model is designed,with the upper level planning for the bus network wiring problem and the lower level planning for the passenger flow allocation based on a stochastic user model.The final calculation results show that the model is feasible and reasonable.