Solving a location-routing problem with a multiobjective approach: the design of urban evacuation plans

Fires, earthquakes, floods, acts of terrorism, nuclear accidents and other catastrophes that may occur in (or affect) urban areas, constitute an important concern for emergency and rescue services, such as fire departments and medical assistance. This paper introduces a multiobjective approach to identify evacuation paths and the location of shelters for urban evacuation planning. Six objectives including risks associated to paths and shelter locations, evacuation path lengths, and the final evacuation time from shelters to, for instance, hospitals, were considered in a mixed integer linear programming model. The proposed approach was tested for a simulated fire situation concerning the historical urban city center of an old European city (Coimbra, Portugal). The modeling approach may also support other emergency situations for which evacuation plans are pertinent. The solutions generated are compared in the objective space via various graphical techniques and represented via color-coded graphics in a Geographic Information System (GIS) where evacuation routes, rescue facilities and the respective building assignments are shown.

► We introduce a multiobjective approach in a urban location/routing problem.
► Urban evacuation plans are conceived considering path lengths and path risks.
► Shelter sites are chosen according to objectives related to risk and evacuation time.
► Test results were obtained for the historical center of an old European city.
► Efficient solutions were generated, and were compared and represented in a GIS.