Highway maintenance in Australia15 is performed by crews operating out of maintenance depots. The Victoria region is planning a major realignments of its depots to provide more effective service to the i = 1,

c, 276 highway segments in the region. A total of 14 sites must be selected from among the possible depot locations j = 1,

c, 36. Review of the possibilities has determined the indicators ai,j ! c 1 if a depot at j is close enough to provide good service to segment i 0 otherwise Not all segments will be able to receive this good service, so planners wish to select 14 locations to minimize to sum of service requirements si at segments with inadequate service. Formulate an ILP model to select an optimal collection of depots using the decision variables (i = 1,

c, 276;

j = 1,

c, 36)

xi ! e 1 if depot j is selected 0 otherwise yi ! e 1 if segment i goes inadequately covered 0 otherwise