The Queue Model Of Truck Service With Appointment Mechanism In The Container Terminal

In container terminal, at least 90% containers are carried by trucks through the gate. However, the entrance time of trucks is random and uncertain. There may be too many trucks arriving at gate during the peak hours, resulting in heavy congestion at gate and in the terminal. The congestion not only decreases operation efficiency of the terminal, but also increases the truck emissions. Truck appointment is a widely used method that can relieve gate congestion effectively and decrease truck turn time. But truck appointment system is so complex that it relates too many terminal plans. For example, truck queues in the terminal are consist of several small queues like queue at gate and queue at yard and truck queues are affected by internal operation plan in the terminal. Therefore, how to design truck queue model in the terminal, thereby cooperating the terminal plan with truck appointment is an urgent issue to be addressed.This paper designed the truck queue model from three aspects to show the arrival pattern under the appointment system. First, considering the truck queue at gate and yard, we designed a truck appointment model based on BCMP queuing network to describe the service process of trucks. The objective of our model is to minimize the truck turn time in the terminal. And then we use genetic algorithm and point-wise fluid flow approximation method to solve the model. Finally, empirical analysis was used to test the model and algorithm.Second, considering the influence by internal terminal plan, we designed a truck appointment model based on coordinated service of internal and external trucks at container terminals. Vacation queue theory was used to describe the service process for inner trucks and external trucks simultaneously of gantry cranes. Gate through capacity and the loading and unloading plan of yards are considered when optimizing truck appointment quotas. Last we used genetic algorithm to solve the model and empirical experiments were used to illustrate the validity of the model.Finally, considering the allocation of gantry cranes between the inner trucks and external trucks, we designed a truck appointment model based on yard gantry cranes allocation. We used vacation queue model with policies to describe the process and allocation of gantry cranes. Truck appointment quotas and gantry crane allocation were optimized under the constraint of gantry crane scheduling, gate through capacity and loading plan at yards. And then we used genetic algorithm to solve the model and tested the model with empirical analysis.The results showed that truck appointment method can relieve congestion in the terminal effectively and increase terminal operation efficiency. The related queue model can validly describe the service process of the terminal. Thus, the proposed model can provide reference to terminal operator.