Research On Transit Assignment Model And Algorithm Based On Line And Node Strategies

Transit assignment technology is one of the key technologies for scientifically planning transit systems.Transit assignment is to assign the obtained passenger demand to each transit line in the transit network according to the principle of transit passenger assignment,further find the number of passengers in each section of the transit network.After calculating the total travel cost of each OD pair,we can analyze and evaluate the city’s transit network based on the obtained results.With the expansion of urban transit scale and the growth of population,the quantity of computation required for transit assignment is also increasing.Traditional transit assignment models and algorithms can no longer meet the efficiency and accuracy of the calculation of transit assignment.A more efficient transit assignment model and its solution algorithm are proposed.The main research contents are as follows:Firstly,passengers’ practical choice behaviors are comprehensively analyzed in this paper.The concepts of line strategy(LS)at the origin and transfer nodes and node strategy(NS)along the on-board lines are proposed.The LS/NS proportion is defined as the proportion of passengers that selects a LS/NS.The passengers’ line and node strategy(LNS)choices are assumed to follow UE principle,that is,no passenger can reduce his/her total travel time by changing his/her LS at the origin and transfer nodes or by changing his/her NS when onboard a line.A passenger flow assignment model satisfying the LNS-based UE conditions is presented based on these LS/NS concepts and LS/NS proportions,which is formulated as a VIP(Variational Inequality Problem).The inclusion of the NS proportion eliminates the need for passenger assignment on a large augmented graph,drastically reducing the modeling complexity and making it easier to track all passengers’ travel routes.Moreover,the transfer constraints—which are crucial in practical decision-making on transit networks—is explicitly included,further reducing the set of feasible transit strategies.Furthermore,some extant strategy-based transit assignment models are shown to be a special case of the proposed model when the transfer constraint is removed.Secondly,in order to solve the passenger flow assignment model based on LNS,the MSA algorithm,the MSWA algorithm,and the SRA algorithm are improved,and the projection algorithm(GP)is applied to the field of transit assignment for the first time.Through the comparison of the operational efficiency of the four algorithms,the projection algorithm shows a huge advantage.Finally,the model and algorithm are verified and analyzed on a small transit network and a large Beijing transit sub-network.In addition,it also discussed the influence of factors such as transfer constraints,departure frequency,transit capacity,route and station setting rationality on passenger flow in the transit network,and how it helps network designers evaluate the network design and solve the transit network congestion problem with the best solution,thereby improving network design.