In this paper we considered a vehicle routing problem that
arises when a set of customers have waste that must be collected
by vehicles. Empty vehicles leave the depot and collect waste
from customers, emptying themselves at waste disposal facilities
as and when necessary (so typically a vehicle route would involve
multiple disposal facility visits). In the problem we considered
there were a significant set of constraints relating to real-world
considerations. Specifically we took into consideration time
windows associated with customers, disposal facilities and the
depot. We also took into consideration a driver rest period.