Optimization of oil tanker schedules by decomposition, column generation, and time-space network techniques

Ship scheduling problem is an important operational level planning problem in maritime logistics. In this paper, we show how we designed and developed a mathematical model for real-world tanker scheduling problem in Japan. Tanker operators own their fleet of tankers and make their schedules for the next several weeks for meeting customers’ demands. However, due to the high uncertainty of the ship operations and unexpected changes of demands, the schedules has to be revised frequently. Our methodology allows the operators to determine schedules that minimize the operational cost in a few minutes. These solutions provides cost improvements for tanker operators, as measured by reduction of 5–16%.