Layout planning for facilities with fixed shapes and input and output points

This paper focuses on the facility layout problem in which each facility has a predetermined shape and input and output points. In the problem, facilities are placed within a given floor, and the spatial coordinates and orientation of each facility are to be determined. We give a mixed integer programming (MIP) model for the layout planning problem with the objective of minimizing the sum of rectilinear distances weighted by flow amounts between input and output points of the facilities. Using the MIP model, we develop a two-phase algorithm in which an initial layout is generated in the construction phase and is improved using four improvement methods applied iteratively in the improvement phase. Results of computational experiments show that the proposed algorithm gives better solutions than existing algorithms.