Optimized Design Of Dynamic Radial Spoke Network For Intermodal Transport Of Hazmat

With the increasing demand for chemical products in China,the transportation of dangerous goods has become an essential part of industrial production.At the same time,as a safe,economical,and efficient transportation mode,highway rail intermodal transportation is developing rapidly in China.In order to give full play to the advantages of high railway safety and flexible highway connection,highway rail intermodal transportation should be prioritized for long-distance transportation of dangerous goods.In addition,the hub and spoke network is an effective network structure for integrating logistics resources,reducing transportation costs,and improving operational efficiency.The combined transportation of dangerous goods by highway and rail can be optimized based on the hub and spoke theory.Therefore,the optimization problem of highway and rail intermodal transportation of dangerous goods can be summarized as the problem of location of highway and rail transshipment nodes for dangerous goods in highway and rail intermodal transportation(i.e.,location of hubs in a hub and spoke network),and the problem of path optimization related to the transportation cost of dangerous goods(i.e.,hub and spoke optimization in a hub and spoke network).Studying the above two key issues will help reduce the risk of transportation of dangerous goods,reduce comprehensive transportation costs,and improve transportation efficiency,And better serve the society.This paper studies the dynamic hub and spoke network problem of highway railway intermodal transportation of dangerous goods.There are multiple alternative hub nodes in this network,and the same hub node can connect multiple highway nodes.Dangerous goods are transported between axles by railway,and between axles by highway,with some routes on the highway being spoke.Firstly,based on a systematic review of the literature on location and path optimization issues,this paper elaborates on the dynamic pivot spoke network problem.Secondly,design a dynamic hub and spoke network for highway and rail intermodal transportation.When studying the location of axis locations,comprehensive consideration should be given to such constraints as the construction cost and transfer operation cost of axis nodes,waiting time within axis nodes,and transfer times.In addition,consideration should be given to the risk level differences of operators within axis nodes and surrounding permanent residents.Different levels of screening should be conducted based on population density,using distance as an indicator,Establish a dual objective 0-1 integer programming model for axle location in a dynamic hub and spoke network for highway rail intermodal transportation of dangerous goods with the goal of minimizing cost and risk.Convert the model into a single objective optimization problem through linear weighting,and improve the tabu search algorithm to solve the model.Thirdly,aiming at the optimization problem of dynamic hub and spoke networks for highway rail intermodal transport of dangerous goods,while considering transportation costs,taking into account carbon emission costs,soft time window penalty costs,and other indicators,a risk measurement model is established with the number of people affected by the transport of dangerous goods as a parameter,to achieve the combined optimization of multiple transportation paths between different starting and ending points within the same dynamic hub and spoke network,and to design a non dominated sorting genetic algorithm,Improve the population initialization process and crossover operator,and introduce an elite strategy solution model of collaborative selection.Finally,this paper selects 53 alternative axis nodes and 48 urban OD pairs for the transportation of dangerous goods in the northwest,southwest,and Beijing-Tianjin-Hebei regions as examples to verify the effectiveness of the axis location model,spoke optimization model,and corresponding algorithms.Using MATLAB to solve the model,compare and analyze the common algorithm and the improved algorithm,and perform corresponding sensitivity analysis.The results show that under different transportation volumes and conditions,the model and algorithm designed in this paper can solve the optimal axle node and corresponding optimization path comprehensive scheme,which can take into account multiple indicators such as comprehensive risk,transportation cost,carbon emissions,etc.The conclusions obtained can support the optimization of hazardous goods highway rail intermodal transportation axle node and intermodal transportation path,providing a quantitative scientific basis for decision makers.