Optimization Of The Feeder Transport Product Oriented Highway And Railway Intermodal Transportation

In recent years,China’s High-speed railway network has been formed on a large scale,but the layout of network is quite unbalanced.There are still some shortcomings in remote areas,such as insufficient coverage density and poor accessibility of station.In this context,China has proposed a bus-rail intermodal product named High-speed railway trackless station,which can expand the radiation range of High-speed railway stations through the seamless connection between bus and railway.However,in the actual transportation organization,due to the point-to-point transportation of bus-rail intermodal transportation products,there are serious waste of vehicle resources,and the transfer time of passengers is tremendous.In this context,aiming at solve the current operation problems of High-speed railway trackless stations,this paper optimizes the design of busrail intermodal transportation products.The main research contents are as follows:(1)Based on the subscribe travel mode,this paper proposed a bus-rail intermodal transportation service mode.Based on the intermodal network of High-speed railway trackless station,a set of bus-rail connection service process is designed from passenger reservation to vehicle delivery.According to the whole connection process,the optimization objectives and key factors of bus-rail intermodal transportation products are analyzed to provide theoretical support for the construction and solution of the optimization model.(2)A discrete multi-commodity flow optimization model based on state-space-time network is established.Since the traditional space-time network model can not accurately simulate the real bus-rail intermodal connection scene,this paper records the basic situation of shuttle bus passengers by expanding the state dimension.Considering the network flow balance constraints,passenger demand constraints and shuttle capacity constraints,the bus-rail intermodal transportation optimization model is constructed in the three-dimensional state-space-time network,and the penalty function is introduced to ensure the passengers’ transfer time.The model takes minimizing vehicle operation cost and passenger transfer time as the objective function to search for the service route and service strategy with the minimum generalized total cost.(3)An augmented Lagrangian relaxation heuristic algorithm is designed in the framework of block coordinate descent.In order to prevent the emergence of symmetric solutions in vehicle routing optimization and reduce the complexity of solution,the augmented Lagrange multiplier method is used to relax the passenger demand constraints.The objective function is decomposed and linearized according to the variable characteristics.The original problem is transformed into a series of sub-problems finding the shortest path,a labeling algorithm is used to search the shortest path,and each vehicle is solved circularly and iteratively as a coordinate direction.Finally,the model is verified in several cases.