Compact ILP formulations for a class of solutions to berth allocation and quay crane scheduling problems

In this paper, we consider an integrated berth and quay crane allocation and scheduling problem. Existing ILP formulations involve large number of variables and constraints making commercial solvers unsuitable for obtaining optimal solutions. We introduce a class of solutions and present compact ILP formulations to obtain them using commercial solvers on a fast track. The size of the formulations (number of variables and constraints) is very small compared to the existing formulations to find optimal solutions. Further, unlike general optimal solutions, the new class of solutions are easy to implement and thus are desirable from pragmatic angle. The quality of new solutions, evaluated through a number of numerical experiments, appears to be good.