Study On The Optimization Design Of Hazardous Materials Road Transportation Network

In the life cycle of hazardous materials (hazmat), the transportation activity plays a vitalrole. With the traffic volume continuously increasing, hazmat accidents do happen, usuallyresulting in casualties, property damage and environmental problems. Due to the risksassociated with this special cargo, hazmat transportation(HMT) has always been concerned bythe public. Many attempts to design a safe and effective transportation network for hazmathave been made by both academics and practitioners.Nowadays, many study results of HMT network design have been achieved, but priorresearches have at least four limitations.The first limitation goes to the “route selection problem”. In order to optimize thetransportation network for hazmat, it is necessary to identify optional routes, since not all theavailable routes are suitable for hazmat shipments. However, so far this area hasn’t receivedattention. Indeed, some advanced algorithms, rather than simple judgments based on roadcondition or people’s experience, should be used to solve this problem.Second, the hazmat transportation should be broken into two parts: inter-citytransportation and intra-city transportation, each of which will adopt different optimizationmethods, owing to the differences between their impedance characteristics. However, noprevious research has ever made such a distinction.Third, some concerns, such as avoiding transportation disruptions, and diversifyingtransportation risks, should also be taken into consideration.Last, in spite of rich literature on the route optimization, the optimization of hazmattransportation network has received little attention. While the former usually focuses on ashipment from a single origin to a single destination (SOSD), the latter also includesshipments from a single origin to multiple destinations (SOMD) or shipments from multipleorigins to multiple destinations (MOMD). Due to the nature of hazmat, findings drawn fromthe SOSD case are not necessarily applicable to the SOMD or MOMD cases. Theabove-mentioned three cases deserve further systematic exploration and should be discussedin details one by one.To address these limitations, this dissertation deals with the network optimizationproblem associated with hazardous materials road transportation and attempts to provide asystematic exploration. Here come the details.(1) Based on literature review, limitations of prior researches are listed.(2) To fill the gap left by road segment selection, this dissertation put forward a pair ofconcepts about restricted segment: explicit one and implicit one. For the former the structured screening method is employed while for the latter the neural network algorithm is employed.Both algorithms are further verified by simulation.(3) The dissertation proposes the concept of K-optimal transportation network, andanalyzes the five differences between the K-optimal transportation network and K-shortestpath. Then, the solution algorithms are studied from the three aspects SOSD, SOMD andMOMD, and the algorithms can be used to design the K-optimal transportation network ofhazmat.(4) As to the inter-city hazmat transportation, the SOSD case is firstly analyzed:different methods of network optimization are used depending on whether the road network isunderdeveloped or developed. For the former the uncertain evaluation method is employedwhile for the latter a chromosome marker multi-objective genetic algorithm is proposed. Afterthe SOSD case, SOMD and MOMD cases are also discussed in details. Optimization modelsand algorithms for the SOMD case are proposed after a closer look at centralized serviceswith single vehicle, collaborative services with multiple vehicles and decentralized serviceswith multiple vehicles, while those for the MOMD case are proposed by distinguishingcollaborative services with multiple vehicles from decentralized services with multiplevehicles.(5) Similarly, as to the intra-city hazmat transportation, the SOSD case is firstlyanalyzed: depending on whether the road network is underdeveloped or developed, differentmethods of network optimization are used. For the former the uncertain evaluation method isemployed while for the latter a multi-objective hybrid genetic algorithm is proposed. After theSOSD case, SOMD and MOMD cases are discussed. The dissertation applies multi-objectivechance constrained programming techniques, by considering centralized services with singlevehicle, collaborative services with multiple vehicles and decentralized services with multiplevehicles in the case of SOMD, and by differentiating collaborative services with multiplevehicles from decentralized services with multiple vehicles in the case of MOMD.(6) The concept of transport network point and edge repeatability and its formula areproposed. By applying the new formula, the solving method for K-Pareto optimaltransportation network with SOMD and MOMD is set up. Case studies show that the methodis feasible, the K-Pareto optimal transportation networks can not only meet the purpose oftransportation risks diversification, but also avoid some disruption road, well complete thedesign task of hazmat transportation.The optimization methods proposed in this dissertation have been verified by computersimulation, the testing results show that the methods are feasible and the study results canprovide basic theory support for safeguarding the transportation safe of hazmat.