Joint serial lock schedule design and sailing speed optimization on inland waterway for emission reduction

This paper investigates a ship-lock co-scheduling problem (SLCP) where bi-directional ships travel through serial-locks with multiple chambers on inland waterways. With the tightening of environmental regulations and the growing need to improve the navigation efficiency in inland waterway transportation, reducing ship carbon emissions and enhancing lock efficiency have become two essential operational objectives. To tackle this dual-objective challenge, a multi-objective mixed-integer linear programming model is proposed for the SLCP to minimize the stay time and fuel emissions of ships. A multi-objective large neighborhood search algorithm (MOLNS) is developed for multi-objective discrete combinatorial optimization problems as well as the SLCP, where the lockage scheduling and ship speed optimization decision problem is innovatively converted to a project management problem via Triangular Distribution function and solved by the critical path method. Case studies are implemented based on the data extracted from the serial-lock systems in Albertkanaal Canal and Yangtze River. Numerical results demonstrate feasibility of the model and high performance of MOLNS for solving large-scale SLCPs with MOLNS outperforming state-of-the-art methods on multi-objective benchmarks. Sensitivity analysis results indicate the significant carbon emission reduction benefits of ship speed optimization and provide insights of key parameter impacts on SLCP performance.