VRP with Interdependent Time Windows — A Case Study for the Austrian Red Cross Blood Program

This work shows our endeavors to assist the fleet management division of the Austrian Red Cross blood programme by developing an algorithm for the VRP with interdependent time windows. Usually, blood donation campaigns are operating all day long and the collected blood must be transported from campaign locations to a central blood processing facility, where it has to be further processed within a certain amount of time. By considering this constraint, each location must be visited for a number of times during the course of a day. Certain vehicles are scheduled for picking up the stored blood donations and delivering it to the processing facility within the given tim e window. Time windows for each location show a dynamic behaviour as they depend on previous pickup times. In order to solve the problem we develop a savings-based constructive procedure for the VRP with interdependent time window const raints. First, our algorithm calculates the minimum number of pickups for each location and then it determines possible combinations when constructing a tour. Preliminary results on real life data show that we can easily decrease overall tour lengths.