The Weber problem in congested regions with entry and exit points

The Weber problem is about finding a facility location on a plane such that the total weighted distance to a set of given demand points is minimized. The facility location and access routes to the facility can be restricted if the Weber problem contains congested regions, some arbitrary shaped polygonal areas on the plane, where location of a facility is forbidden and traveling is allowed at an additional fixed cost. Traveling through congested regions may also be limited to certain entry and exit points (or gates). It is shown that the restricted Weber problem is non-convex and nonlinear under Euclidean distance metric which justifies using heuristic approaches. We develop an evolutionary algorithm modified with variable neighborhood search to solve the problem. The algorithm is applied on test instances derived from the literature and the computational results are presented. (C) 2014 Elsevier Ltd. All rights reserved.