A Simulation-Based Dynamic Programming Method for Interchange Scheduling of Port Collecting and Distributing Network

As one of the effective methods to reduce congestion, grade intersection has already been changed to interchange in port collecting and distributing network (PCDN) of many Chinese ports, since the first interchange was built in the PCDN of Dalian port in 1924. Due to the growing demand for port freight transportation, congestion in PCDN is becoming one of the inevitable problems that need to be solved. This paper addresses the best interchange scheduling multistage decision problem in PCDN at a network level. The main challenges are how to estimate the delay time and cope with high uncertainties in port network and PCDN. Therefore, a simulation-based dynamic programming (DP) model is proposed with the purpose of minimizing total cost in lifetime period by combining a DP model and two nested simulation models together. Two simulation models are built to figure out the delay cost in the optimization model, which cannot be calculated by mathematical analysis due to complex vehicle travel patterns and irregular traffic volume caused by random events, such as the arrival pattern of ships’, natural conditions, and storage period of cargos. Finally, a real project in northern China is presented as a case study. The proposed method can be applied in similar cases and can help solve analogous complicated multistage problems.

Operational impact estimation of container inspections at Dalian Port: the application of simulation

For the security of ports and the container shipping industry, a key problem for a container terminal is the planning and design of the inspection area. The main goal of this paper is to address an inspection investment planning problem for the international container terminal at Dalian Port using the simulation method. Considering various types of container ships and flexible container truck scheduling and routing, we propose a framework combining an Arena-based simulation model with a developed optimization procedure. Two components of this integrated framework realize information communication via the interface of Visual Basic for Applications. Under the potential inspection protocol, simulation experiments are designed and carried out for investigating the operational impact of container inspections for different allocations of inspection resources at the terminal, including the turnaround time of external trucks, the number of trucks waiting in the inspection area, etc. This paper includes the description of the conceptual framework, the detailed simulation model, the experimental design, and the simulation results.