LOCATING FACILITIES 129 G 15 B 10 10 5 10 15 15 10 Figure 5.14 Road network showing travel time in minutes between locations 1 | Covering problem Distance matrix Maximum Single location Maximum time Two locations 10 mor 10 Maximum time Figure 5.15 Solution to the covering problemWORKED EXAMPLE Figure 5.14 shows part of a road network, with the travel time (in minutes) shown on each link. Where would you locate a depot to give best customer service? How many depots would be needed to give a maximum journey of 15 minutes? Solution We could, of course, do the calculations for this covering problem, finding the maximum time for each town and identifying the best, and then finding the combination of towns that gives service times of less than 15 minutes. There is no need for this, as a lot of soft- ware solves network problems and Figure 5.15 shows a printout from a simple package. As you can see, if a single location is needed the package recommends town C, giving a maximum journey of 25 minutes. If this is too much, facilities at A and I will reduce the maximum journey to 15 minutes