Optimizing container relocation operations at container yards with beam search

- We developed a novel and efficient heuristic to obtain good solutions for the container relocation problem.
- The proposed heuristic is embedded in the beam search to further obtain better solutions.
- Three benchmark data sets were tested and the results were compared with state-of-the-art algorithms.
- The beam search can obtain better results than other state-of-the-art algorithms in the benchmark instances.

Container relocation problem (CRP) involves the retrieval of all containers from the container yard with a minimum number of relocations. The CRP is an NP-hard problem such that the large-scale instances cannot be solved to optimality by exact solution methods within a reasonable computational time. This article proposes a beam search (BS) algorithm embedded with heuristics to evaluate the problems. The proposed beam search is tested on benchmark instances and compared with other leading heuristics from the literature. Computational results demonstrate that the beam search algorithm is compatible with other heuristics and can obtain good solutions in short time.