Title: Tramp ship routing problem considering the implementation of carbon intensity indicator

Authors: Ming Yin; Kaifei Chang; Dequan Zhou; Xufeng Tang

Addresses: College of Transport and Communications, Shanghai Maritime University, Shanghai, China ' College of Transport and Communications, Shanghai Maritime University, Shanghai, China ' College of Transport and Communications, Shanghai Maritime University, Shanghai, China; Shanghai International Shipping Institute, Shanghai, China ' College of Transport and Communications, Shanghai Maritime University, Shanghai, China

Abstract: In 2023, the International Maritime Organization (IMO) formally implemented the mandatory carbon intensity indicator (CII) rating requirements, linking ships' carbon emissions to transport activities. The introduction of CII has significantly impacted shipping companies' fleet operation planning. In this paper, we examine tramp shipping companies' market contract selection and fleet scheduling under the backdrop of CII implementation. By incorporating the CII ship rating requirements into the constraints of a tramp ship routing and scheduling optimisation model, we expand the current research on the tramp ship routing problem to consider new carbon emission regulations. Additionally, a tailored adaptive large neighbourhood search (ALNS) algorithm is designed to provide a solution tool for large-scale instances of the model. Finally, we perform sensitivity analysis experiments on the model using multiple sets of different scales. The multifaceted impact of CII implementation on the fleet operation of shipping companies is discussed based on the experimental results.

Keywords: carbon intensity indicator; CII; tramp shipping; ship scheduling; batched cargo selection; adaptive large neighbourhood search; ALNS.

DOI: 10.1504/IJSTL.2026.150451

International Journal of Shipping and Transport Logistics, 2026 Vol.22 No.1, pp.118 - 148

Received: 09 Mar 2025
Accepted: 21 Aug 2025
Published online: 14 Dec 2025 *

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