Research On Optimization Theory And Methord For Multi-block Train Formation Plan

With the rapid development of economy and deepening of reform and open policy in China,the railway freight transportation is developing towards logistics and heavy load.The current railway car flow organization mode which mostly using single-block trains meets some challenges.The multi-block train can be regarded as an effective means to improve the efficiency of railway freight organization,which has practical significance in improving the economy and timeliness of China's railway freight at this stage.From the perspective of train composition,a single-block train is a specific type of multi-block train.Studying the operation features of the multi-block trains helps to reveal the essence of the car flow organization,which is of great theoretical significance.Based on the detailed analysis of the domestic and foreign literature in car flow organization theory,considering the China railway realistic situation and management-operation mechanism characteristics,a systematic study is done on the car flow organization optimization theory for the multi-block trains.The main research contents include:(1)Following the thought of multi-stepped optimization,the organization process of multi-block train is divided into three sub-problems:car flow routing,single-block train formation plan and multi-block train formation plan.In the car flow routing problem,the arc-based and path-based optimization method are studied firstly,then combing the tree-shaped path characteristics of the car flow in real-world transportation,an optimization models based on tree-shaped path characteristics are established.Different car flows with different origins but with same destinations meet at a yard will merge to become one car flow,which is called as merged car flow.The decision variable is the first yard passed by the merged car flow,the objective is to minimize the comprehensive cost which includes mileage and the car relaying operation at yards while satisfying the railway arc capacity constraints.The model is tested in an actual northeastern China railway network in which the major main lines are the research objects,a heuristic oportimization approach based on the generic algorithm and Lingo software are adopted to solve the model.(2)In the single-block train formation plan problem,the car routing as the given parameters.The arc-based and path-based optimization method are studied first,then combing the tree-shaped classification path characteristics of the car flow in real-world transportation,an optimization models based on tree-shaped path characteristics are established.The car flows originated from a yard or originated from other yards and classified at this yard,which are destined to the same yard will become one car flow called as technology car flow.The decision variable is the first classified yard of the technology car flow.The objective is to minimize the sum of accumulation delay,classification delay while satisfying the constraints of the number of shunting lines and the yard capacity.The model is tested in an actual northeastern China railway network,a heuristic oportimization approach based on the generic algorithm and Lingo software are adopted to solve the model.(3)Different with the single block-trian formation in which each block is transported by a direct train,in multi-block train foramtion plan,the block just plays a middle role from car to train.Considering both the formation method and the change of the complementary car flow,there are totally four different types,the union multi-block train with variable basic-complementary weight ratio,the union multi-block train with fixed basic-complementary Neight ratio,the linking multi-block train with variable basic-complementary weight ratio,the linking multi-block train with fixed basic-complementary weight ratio.Then the technical benefits which can be achieved by replacing single-block trains with two-block trains are systematically analyzed and summarized,which includes the train operation cost,accumulation cost,the train make-up cost,the waiting cost of blocks and the extra halting cost of the two-block trains at the block-swap yard.The car routing and the blocks established in the network are pre-known.An optimization model is established aiming at the maximization of the saved total car-hour consumption in comparision with the single-block train while satisfying the constraints of correlation between different multi-block trains.The multi-block train is expressed as a combination which includes the origination,the destination and the block-swap station.The model aims at determine whether the multi-block train is provided or not.The model is tested in an actual northeastern China railway network,the Lingo software are adopted to solve the model.(4)For the change of complementary car flow,not all cars in the complementary block can be allocated to the multi-block train.If the redundant car flow is district flow.then the multi-block train formation plan will dispatch a district train for the excess car flow.But in the real-life world,if the volume of the redundant car flow is small,from the economic benefits prospect,the redundant district car flow merge with pick-up car flow will be more reasonable.The technical benefits of combing district car flow and pick-up car flow are analysised.and a comprehensive optimization model of district train and pick-up train is established,which is tested in a small railway network.Then from the railway network level,the interaction effects among multi-block train,district train and pick-up train are analysised.A comprehensive model of multi-block train,district train and pick-up train formation plan is established under given the car routing and the established block and the car flow allocated to the block,which is aiming at the minimization cost while satisfying the constraints of correlation among multi-block train,district train and pick-up train.The model aims at determine whether the multi-block train is provided or not and whether the district car flow merge with the pick-up car flow.The model is tested in an actual northeastern China railway network,the Lingo software are adopted to solve the model.(5)In the model of multi-block train formation plan with the constraints of correlation,the car flow of a block can only be allocated to one multi-block train.In the real-life world,if the redundant car flows are allocated to other multi-block train,which can increase the the quantity of multi-block train and take advantage of saving organization cost of multi-block train to a greater degree.When car flows of one block allocated to two or more multi-block train,the related multi-block trains are nested.The nested interference among different multi-block trains are analysised.An optimization model of multi-block train formation plan with the nested structure is established aiming at the minimum organization cost while satisfying the constraints of the completeness of car flow and the weight of trains.The model aims at determining the allocation proportion of car flows among different trains.The model is tested in an actual northeastern China railway network,the Lingo software are adopted to solve the model.