Container Drayage Transportation Under The Mode Of Multi-trailer Drop-and-pull:Modeling And Optimization

Container transportation has been playing an increasingly important role in the entire global logistics due to its advantages of high efficiency.However,in the traditional container transportation,tractors and trailers both wait at the customer location until the load/unload process is finished.This will lead out plenty of problems,such as long waiting of tractors,low efficiency and high expense of transportation.In container transportation with drop-and-pull mode,trailers wait at the customer locations,while tractors continue traveling instead.With such consideration,it is possible for tractors to avoid waiting simultaneously with trailers,raise tractors turnover rate and reduce the amount of tractors employed.Compared with the traditional container truck transportation with one trailer pulled on one tractor,the new mode which allows one tractor pulling multi-trailer meanwhile can increase vehicle capacity and greatly improve transportation efficiency.This kind of transportation mode has been widely applied in the container drayage transportation in Europe,but barely studied in the research committee.This thesis will focus on multi-trailer drop-and-pull and launch research based on the work of other exports and scholars.Generally,the main contributions are as follows:(1)The multi-trailer drop-and-pull problem is classified into two modes:none-mix-trailer mode and mix-trailer mode.Two optimization mathematical models are constructed respectively which target at the minimization of route duration time.The experiment results show that mix-trailer has more potential to improve tractor efficiency and reduce transport costs.(2)The window partition algorithm is firstly used to solve mix-trailer of multi-trailer drop-and-pull problem,and algorithm validity is studied by experiment.Further experiment is conducted to explore the characteristic of multi-trailer drop-and-pull problem.Experimental results show that the window partition algorithm is effective,especially for narrow time window cases.(3)Aiming at the characteristic of multi-trailer drop-and-pull problem,we design an improved simulated annealing algorithm and a Clarke-Wright algorithm respectively.Comparative tests are employed for one-tractor-two-trailer and one-tractor-one-trailer,and the efficiency of multi-trailer transport is testified.The results show that one-tractor-two-trailer can reduce transportation time by 21.35%on average,compared with one-tractor-one-trailer.A large amount of experimental analysis of the proposed algorithms indicates that the modified Clarke-Wright algorithm is significantly useful and effective with 19.06%reduction of objective value on average compared with the other.