A Value-at-Risk Based Approach To Multi-Hazmat Transportation And Routing Problem

With the development of chemical industry in China,the demand of hazardous material(hazmat)is also increasing and China has become the world’s largest country in the hazmat industry.In particular,the accidents that happen during the transportation of hazmat account for 30%-40% of the total number of hazmat accidents and have resulted in serious consequences.In the existing literature,few researchers combined the multihazmat transportation with railway network.In addition,there are also few researches considered the risk preference of decision makers.Considering the serious result of hazmat accidents and the consolidation risk in hazmat transportation,we study the multi-hazmat routing and scheduling problem in railway networks based on Value-at-Risk model and features of hazmat transportation.We present a MIP model and consider both the risks incurred in yards and on service legs to optimize the risk cost in railway network.Due to the inherent complexity of this problem,we propose an exact algorithm based on Va R approach and a tabu search algorithm to solve it.Numerical experiments are carried out on instances generated based on a real railway network.The results verify the efficiency of our proposed solution approach.Then we analyze the effect of different parameters to the risk cost and provide managerial insights.We also show that the model we proposed can provide more flexible routing and scheduling plans with confidence levels under different risk preferences of decision makers.The experiment results indicate that risk-aversion decision makers are more likely to use the outer routing and yards to transport hazmat,which will result in a longer but safer routing choice,and avoid consolidation transportation.