An iterative MILP-based approach for the maritime logistics and transportation of multi-parcel chemical tankers

• Iterative MILP-based approach to the ship routing and scheduling problem.
• Operation of a fleet of heterogeneous multi-parcel chemical tankers.
• Optimal routes for the ship fleet with maximum profit.
• Solution of a real case study of a company operating in South-East Asia.
• Better computational results than other alternative reported solution techniques.

The cost-effective routing and scheduling of a fleet of multi-parcel chemical tankers represents a central decision making process in both chemical and shipping industry. Ships designed for the transport of liquid or gas in bulk are called tankers. Shippers seek to choose the cargos to transport and determine the optimal route that the ship should follow to maximize its profit. Due to determining the optimal assignment and routing decisions of a large set of cargos transported by a ship fleet is inherently NP-hard, real-world problems are either intractable or result in poor solutions when solved with pure optimization approaches. To overcome this limitation, this work introduces a new continuous time precedence-based MILP mathematical formulation that is then embedded within a heuristic-based algorithm in order to obtain near-optimal solutions to large-scale problems. The applicability and efficiency of the proposed approach is illustrated by solving a real case of study corresponding to a sea-cargo shipping company operating in South-East Asia. Computational results show notable improvements and better performance when compared to other alternative reported solution techniques.