Reducing Truck Turn Times at Marine Terminals with Appointment Scheduling

This paper addresses a critical component of truck appointment systems: scheduling rules. The goal of this study is to gain an understanding of how the various scheduling rules affect resource utilization and truck turn time in grounded operations. Such an understanding could influence terminal operators and appointment service providers to make changes to their current scheduling practice. To this end, this study seeks to develop a framework for the evaluation of (a) the performance of various simple appointment-scheduling rules under a variety of operating scenarios and (b) the major factors affecting the performance of scheduling rules. This study considers two types of appointment-scheduling strategies that were adopted from the health care sector: (a) individual appointment systems (IASs) and (b) block appointment systems. To determine the effectiveness of the scheduling strategy, this study relies on a simulation model of a container terminal. Simulation is used because it provides a more realistic representation of the complex operations at terminals. In addition, it circumvents the restrictive assumptions of analytical methods. The simulation model developed was constructed with the Flexsim CT discrete event simulation software, the first commercially available off-the-shelf simulation tool for container terminals. The experimental results show a dear benefit for a terminal without an appointment system to use the IAS. Such a scheduling system keeps the yard cranes highly utilized, and it improves the internal yard turn time by about 44%. With the proper spacing between appointments, the IAS can be effective even when a good portion of trucks are walk-ins, no-shows, or late (up to 1 h).