The pipelines and cable trays location problem in naval design

This paper deals with the determination of optimal locations for pipelines and cable trays in naval design. The problem consists of finding the number and types of cable tray routes to be created between various devices in order to minimize a user defined cost function. We reduce the problem to an ad hoc min-cost multicommodity flow problem with additional constraints imposed by technical requirements. This problem is solved for small-sized instances by using off-the-shelf optimization solvers. We also develop an exact relax-and -cut strategy that allows to handle medium-sized instances. For larger instances, we propose a family of heuristic algorithms consisting on the combination of two phases: (I) Construction of initial cable trays paths; and (II) Transformation to feasible cable trays verifying the technical requirements. For each of them, we also propose different strategies which give rise to several algorithms. These algorithms are compared on a computational experience using two types of instances: the first one based on random instances of different sizes and the second one based on instances with well-defined corridors to asses the availability of our methodology to enforce the creation of cable trays. Finally, we also analyze a real size case study provided by our industrial partner, Ghenova, a leading Naval Engineering company, validating our proposal to find solutions for this problem.