  In many applications of vehicle routing, a set of time windows are feasible
for each visit, giving rise to the Vehicle Routing Problem with Multiple Time
Windows (VRPMTW). We argue that such disjunctions are problematic for many
solution methods, and exemplify this using a state of the art Adaptive Large
Neighbourhood Search heuristic. VRPMTW comes in two variants depending on
whether the time used en route must be minimised. A more compact and corrected
mathematical formulation for both variants of the problem is presented, and new
best solutions for all but six benchmark instances of VRPMTW without time
minimisation is found. A new solution representation for VRPMTW with time
minimisation is presented, its importance is demonstrated and it is used to
find new best solutions for all but one benchmark instance of VRPMTW with time
minimisation.
