Research On Vehicle Routing Optimization For Hazardous Materials Transportation Based On The Risk Of Each Vehicle

As a by-product of industrial development,large quantities of hazardous materials are shipped in the transportation network every day.The properties of hazardous materials include flammability,explosive,poisonous,corrosivity,and radioactivity.Once an incident occurs during the transporation procedure,people will suffer by injuries and have property losses.Thus,the risk is the critical point of hazardous materials transporation.In most of previous studies,the vehicle routing optimization for hazardous materials tranpsotation is usuaully difined as a bi-objective model,simultaneously minimizing the total risk and the transportation cost.However,if simply consider the total risk of a fleet,a situation may exist where the risk of a specific vehicle is very high,and once an incident occurs for the vehicle with a high risk,it will cause a large amount of damages.This paper takes the risk of each vehicle as the key,study the vehicle routing for hazardous materials transporation.On the basis of this,the research works are carried out from two aspects,those are the risks are fixed parameters and the risks are based on actual load of vehicles.Each aspect includes two scenes,and the in-depth studies will be based on thease four scenes.The main innovative works of this paper are as follows:1.Bi-objetive Vehicle Routing Optimization for Hazardous Materials Transportation with No Vehicles Travelling in Echelon.Focus on the risk of each vehicle and the probable chain of incidents caused by vehicles travelling in echelon,develop the bi-objective vehicle routing model for hazardous materials transportation with no vehicles travelling in echelon,simultaneously minimizing the maximum risk of each vehicle and the transportation cost.A two-stage exact algorithm is developed based on the ε-constraint method.The waiting times to avoid vehicles travelling in echelon are computed separately in Stage 2 by a polynomial time algorithm,and save the computational time.An approximation approach is proposed for this two-stage algorithm for large-scale problems.Furthermore,the approximation ratio and time complexity of this approximation algorithm are proved.Several managerial insights are derived from computational experiments and sensitivity analysis.2.Bi-objetive Vehicle Routing Optimization for Hazardous Materials Transportation Considering Failed Edges.Based on the practical situation of failed edges after serious incidents.Two different strategies to deal with failed edges are given in the first place.For the forethought strategy,the failed edges will be considered before the departure of vehicles and determine the vehicle routing plan.For the real-time-detouring strategy,the vehicle routing plan is given by ignoring the probabilities of failed edges.The vehicle routing models are developed for both strategies,simultaneously minimizing the maximum risk of each vehicle and the transportation cost.According to the principles of ε-constraint method,an exact algorithm is developed.There are several improvements in this algorithm,including a fast algorithm to explore the lower bound of e based on a property,a pre-treatment to prevent the generation of a kind of dominated points,and constraints on infeasible paths.Develop an approximation algorithm for large scale problems,and analyze the approximation ratio and time complexity.The transportation costs and computational times between strategies are compare.Finally,computational results and sensitivity analysis are provided.3.Bi-objetive Vehicle Routing Optimization for Hazardous Materials Transportation with Actual Load Dependent Risks.Take the risk depend on the actual loads of the vehicles as an important factor.Firstly,provide the definition of actual load dependent risk,and develop the bi-objective vehicle routing model for hazardous materials transportation with actual load dependent risks.This model is based on two-commodity formulation,in which is more suitable for the parameters depended on the actual loads of the vehicles.Based on the principles of ε-constraint method,an exact algorithm is developed.The improvements include a fast algorithm to compute the lower bound of e,a pre-treatment to prevent the generation of a kind of dominated points,and a fast brunch method to solve the sub-problems in the process of ε-constraint method.For large scale problems,an approximation algorithm is developed,and analyze the approximation ratio and time complexity.Finally,computational results and sensitivity analysis are provided.4.Bi-objetive Vehicle Routing Optimization for Hazardous Materials Transportation Based on Catastrophe Avoidance.Based on the principles of catastrophe avoidance,the risks and objectives are defined by incident consequence.A bi-objective vehicle routing model for hazardous materials transportation with actual load dependent incident consequences is developed,minimizing the maximum incident consequence and transportation cost simultaneously.The exact algorithm to obtain the Pareto optimal solutions is developed based on ε-constraint method.A polynomial time approximation algorithm is developed to deal with large scale problems,and the approximation ratio is analyzed.Finally,the model and algorithms are tested by instances,and the managerial insights are derived from the sensitivity analysis.