Estimating the convoy capacity of restricted waterway: The case of the Suez Canal

For some restricted waterways such as the Suez Canal, all arriving ships have to form a convoy and pass through the waterway one by one without overtaking for safety reasons. In this study, we first propose a novel concept of convoy capacity that incorporates the standard unit of ship and estimate convoy capacity by considering ship types, ship sequence, and ship headway between two consecutive ships. If ship headway is fixed, convoy capacity is a constant value given that the ship sequence is aligned optimally. By contrast, convoy capacity becomes an uncertain variable under random ship headway and random ship sequence. To characterize the system state where convoy capacity is achieved under fixed ship headway, we first formulate an integer programming model for the optimal ship sequence. Then, we develop simulation procedures and explore the probability distribution of uncertain convoy capacity. We demonstrate the proposed methods through the Automation Identification System (AIS) data collected from the Suez Canal. The results can provide managerial insights on the performance of convoy system and the effective strategy for ship traffic control.