Research On Vehicle Route Planning Methods For Hazardous Materials Delivery Based On Heuristic Optimization

The actual transportation of hazardous materials is often full of many uncertain factors,such as uncertain transportation risk and uncertain customer need.Ensuring the safe and efficient transportation of hazardous materials under uncertain factors is a problem that needs to be studied in the planning of hazardous materials transportation.The vehicle routing problem is the core problem in the transportation planning of hazardous materials.In this study,the hazardous materials transportation vehicle routing problem is studied from uncertain transport risk and uncertain customer demand.In order to solve the problems studied,the hazardous materials vehicle routing planning method based on stochastic time-dependent risk and hazardous materials vehicle routing planning method based on dynamic customer demand are proposed respectively.The proposed methods can obtain a safe,economical and efficient hazardous materials vehicles dispatching scheme.The specific work of this study is as follows.1.The hazardous materials vehicle routing planning method based on stochastic time-dependent risk is proposed.Aiming at the uncertainty of risk in the process of hazardous materials transportation,a stochastic time-dependent risk model is established considering the real-time load of vehicles and the stochastic timedependent population density of road sections.This model is mainly established on the basis of traditional risk model.Based on the stochastic time-dependent risk model,a robust multi-objective vehicle routing problem optimization model is established to minimize transportation risk and cost.According to the multiple constraint properties under the built model,a hybrid multi-objective evolutionary algorithm and a two-stage algorithm for solving the problem model are designed with the Nsga-ii algorithm as the main framework.The proposed algorithms are tested on the modified Solomon VRPTW instance.The results show that the two algorithms have good performance in solving the optimization model of the robust multi-objective vehicle routing for the transportation of hazardous materials.At the same time,the numerical experiments of the proposed model are compared with the multi-objective vehicle routing optimization model,which proves the effectiveness of the proposed model.2.The hazardous materials vehicle routing planning method based on customer dynamic demand is proposed.A robust multi-objective dynamic vehicle routing optimization model is established to minimize transportation risk and cost for the dynamic customer demand in the process of hazardous materials transportation.The model increases vehicle dwell time in the depot by allowing late vehicle departures and multi-trip deliveries to allow new customers to dynamically insert into shipping routes.In the solution strategy of the model,the whole working day is divided into a series of time slices to transform the dynamic vehicle routing problem into the static vehicle routing problem in each time slice.According to the urgency and sufficiency of the service time of new customer requests in each time slice,a local optimization algorithm and an improved large neighborhood search algorithm are developed respectively.The proposed algorithms are tested on a DVRPTW instance.The results show that the proposed algorithms have good performance in solving the optimization model of the robust multi-objective dynamic vehicle routing problem for the transportation of hazardous materials.It can quickly plan a safe and economical distribution route to meet the dynamic needs of customers.