Research On The Optimization Of Hazardous Materials Transportation Path Under The Condition Of Road Traffic Restriction

As China continues to undergo the process of industrialization,the types and quantities of hazardous materials required in all areas of production continue to grow,which in turn leads to an increasing demand for the road transport of hazardous materials.Unlike the transport process for general cargo,the inherent risk characteristics of hazardous materials place new demands on road managers and transporters.To alleviate the possible consequences of accidents in the process of road transport of hazardous materials,China’s government departments have introduced a variety of measures to control the road restrictions on the transport of hazardous materials vehicles,including a complete ban on the use of road sections,a ban on the use of designated periods of time or for different types of hazardous materials to restrict the use of different management methods.But in different transport networks to take different road restriction strategy,will directly affect the road network in the size of the transport risk and hazardous materials transport route decision.However,there are few studies at domestic and foreign level on the design of road restriction strategies for a given transportation network,and previous studies are only on the optimization of hazardous materials transportation path selection under the given restriction conditions.In view of this,the thesis considers the formulation of road restriction strategy and the selection of hazardous materials transportation route at the same time,and studies the optimization of hazardous materials transportation route under road restriction conditions from the perspective of static risk and dynamic risk respectively.In a view to provide a decision basis for the government department to formulate a reasonable road restriction strategy and provide a reference for the hazardous materials transport enterprises to choose the optimal transport path.The main work of this paper is as follows:(1)Research on static risk-based road restriction strategies and transportation path optimization problems.On the basis of analyzing the demands of government decision-making departments and hazardous materials transport enterprises,a essential two-layer planning model with the objective of minimizing the maximum roadway risk in the upper layer and minimizing the transportation cost in the lower layer is built.The effective interaction between the upper and lower layers is achieved by using the lower layer optimization results as the feasible domain of the upper layer model,and then making the upper layer results as the constraints of the lower layer model.At the moment,considering that the lower layer model is only pursuing the minimum cost,it is possible to miss some high-risk sections,thus the lower layer model is extended to a dual-objective model pursuing the minimum transportation risk and transportation cost together.The practicality of the model and the effectiveness of the algorithm are verified by utilizing the stochastic grid network arithmetic example.The results show that the improved model is more effective in restricting traffic,and can provide more optional paths for enterprises than the basic model under the restriction strategy.(2)Research on dynamic risk-based road restriction strategies and transportation path optimization problems.By considering the dynamic characteristic that the risk of partial road sections in the transportation network may change periodically with time,a two-layer multi-objective planning model under dynamic risk is built.Converting it into the combined form of multiple static problems,a roadway restriction strategy including both roadway prohibition and time period restriction is obtaining.The nodal restriction strategy and the recursive formula of departure time window based on this model are designed.And partial road sections in the random grid network algorithm are set as dynamic risk sections,and verified the feasibility of the traffic restriction strategy.The results show that the combination of roadway restriction strategy and nodal restriction strategy can reduce the transport risk and optimize the risk distribution,and guarantee that there is no sudden increase in risk when vehicles are detoured.By applying this method to multiple origins and destinations,a road network restriction strategy is obtained for the transportation of a single type of hazardous materials between multiple origins and destinations.(3)The improved Ant colony optimization solution model is designed to address the characteristics of the two-layer model and the advantages and disadvantages of Ant colony optimization.A negative feedback mechanism and a backtracking mechanism are introduced to enhance the success rate of ant exploration paths,and random and pseudo-random proportional selection rules are combined,and a mutation operator and a single-point crossover operator are added to ensure that the ants do not fall into a local optimum.The dual heuristic function strategy is also used to explore more solution spaces,and the algorithm is designed to reduce the running time by dynamic adaptive adjustment of parameters and parallelization of the ant path finding process and the single point crossover operator.The results show that compared with Ant colony optimization,the improved algorithm has a stronger ability to jump out of the local optimum and search for a larger solution space,converges faster,and obtains solutions with significant advantages in both quality and quantity.This thesis researches the optimization of hazardous materials transportation path under the condition of road restriction,and the research results can provide theoretical support for the relevant government departments to formulate road restriction strategy,and provide scientific decision support for the optimization of transportation path of hazardous materials transportation enterprises to further ensure the safety and reliability of hazardous materials road transportation.