The Route Selection Problem In Intermodal Transportation Under Low-carbon Policies

With the rapid growth of global trade and logistics business,freight transportation industry,which is responsible for the circulation of goods,has been booming during the recent years.Meanwhile,this trend has brought a series of negative problems,such as road congestion,noise pollution,carbon emissions.Intermodal transportation,with the help of various modes of trans-portation,can make full use of the advantages of roads,railways,waterways,etc.It could pro-vide more flexible,reliable,and low emission transportation services compared with the uni-modal transportation dominated by road transportation.It is one of the most critical decisions for intermodal transportation operators to choose reasonable routes with economic efficiency and environmental benefits.In the context of the growing concern of the whole society on the environment,more low-carbon policies(carbon tax policy,cap-and-trade policy,carbon offset policy,etc.)will be introduced to mitigate carbon emissions from various industries.Consider-ing that transportation industry is one of the most important carbon emission sources from hu-man activities,operations research in intermodal transportation will inevitably be subject to low-carbon policies.Under such a case,the route selection problem in intermodal transportation under low-carbon policies has emerged.Intermodal transportation network is a complex system involves many participants(gov-ernment,operator,shippers,carriers,etc.),thus the time-space span in the transportation pro-cess could be very large,and the system is easy to be disrupted by external environment.As a result,the route selection decisions in intermodal transportation usually needs to be decided under the environment with uncertain system parameters.Moreover,different low-carbon pol-icies or even the same low-carbon policy under different control efforts will lead to different decisions.Therefore,this dissertation takes the low-carbon policy regulation as decision-mak-ing background,starting with the uncertainty of system parameters.Based on three kinds of decision-making environment(the deterministic decision-making environment,the decision-making environment with uncertain times,and the decision-making environment with uncertain demand and freight rate),the following research on the route selection problem in intermodal transportation have been carried out.(1)Modeling and algorithm design of intermodal transportation route selection problem with road congestion under low-carbon policies.In the deterministic decision-making environ-ment,a general model for intermodal transportation route selection problem under four low-carbon policies is proposed firstly,which is characterized by multiple arcs among the nodes and the impact of road congestion on road transportation emissions.And then,according to the characteristics of the linear integer programming model,an improved genetic algorithm with elite strategy and immigration strategy is designed.Finally,the effectiveness and practicability of the algorithm and model are verified by the analysis of random examples and real examples.In addition,impacts of low-carbon policies and road congestion on route decisions and system carbon emissions are also analyzed.(2)Robust optimization for the intermodal transportation route selection problem with un-certain times under low-carbon policies.Taking the cap-and-trade policy as the policy back-ground,and taking the intermodal transportation route selection problem with unknown value and probability distribution of road transportation time and node transformation time as an ex-ample,this research presents a method using robust optimization(RO)to characterize uncertain parameters,construct robust model,transform and solve robust counterpart,and the uncertain freight rate has further been taken as an example to expand the model we have proposed.Based on the analysis of real intermodal transportation network,the validity and expansibility of the robust model to deal with those problems with additive uncertain parameters are verified.(3)Robust optimization for the intermodal transportation route selection problem with un-certain demand and freight rate under low carbon policies.Under the same background of cap-and-trade policy,in the decision-making environment with uncertain demand and freight rate,the intermodal transportation route selection problem is studied.When the values and probabil-ity distribution of uncertain parameters are unknown,robust optimization is introduced to char-acterize uncertain parameters,construct robust equivalent model,linearize,and solve the prob-lem with multiplicative uncertain parameters.The proposed model is further expanded with consideration of uncertain carbon trading price.Finally,the validity and expansibility of the robust optimization model is verified by examples based on a real intermodal transportation network.(4)Management enlightenments and policy suggestions.Based on the research on the in-termodal transportation route selection problem in the above three decision-making environ-ments,major pro blems of intermodal transportation in China currently are summarized.And then,management enlightenments for intermodal enterprises,as well as policy suggestions for the popularization and improvement of the intermodal transportation for the government are discussed.Given the above main research contents,the study has the following innovations.(1)This dissertation proposes an intermodal transportation route selection model consid-ering road congestion under low-carbon policies and solves the intermodal transportation route selection problem considering impacts of road congestion on carbon emissions under the multi-layer network structure.The model could provide a decision-making framework for the path selection of intermodal transportation enterprises under low-carbon policies.From a practical point of view,it can promote the emission reduction of intermodal transportation industry,ease the congestion of highway transportation,and promote the popularization of intermodal trans-portation.(2)A robust optimization method is proposed to solve the intermodal transport route se-lection problem with uncertain times.The method could deal with problems including param-eter description,modeling,and tractability in the intermodal transportation route selection prob-lem with additive uncertain parameters.The proposed method and corresponding model are suitable for the intermodal transportation route selection problem with additive uncertain pa-rameters and can provide decisions with the trade-off between conservatism and robustness.(3)A robust optimization method is proposed to solve the intermodal transportation route selection problem with uncertain demand and freight rate.This method could deal with prob-lems including parameter description,modeling,linear transformation in the intermodal trans-portation route selection problem with multiplicative uncertain parameters.Theoretically,it could provide solutions to such uncertain decision-making problems or degradation problems.In practice,it could provide low-carbon routes with better robustness for intermodal transpor-tation route decisions with various forms of uncertain parameters.