Optimal vehicle usage in heterogeneous fleet

[akitaylor]

Hi!

We have quite complex optimization scenario with 4 types of vehicles (from small trucks to heavy trucks). Small trucks are faster, cheaper (lower fix cost and dynamic cost also), while larger trucks tend to be slower and more expensive. The problem is that in the solution there are almost always obvious possibilities to change trucks to smaller vehicle class (for example use az unused small truck instead of a larger one). Often times the change could be done without any modification on the tour, no constraint is violated, in other cases some modification is needed.

My question is if there is a recommended way to tune the heuristics to help the optimizer find a better vehicle allocation? For example if ruining complete tours would happen more frequently, it might drive the optimizer to rebuild the same (or similar) tour using a cheaper vehicle. May the "random-route" parameter help this or other parameters should be tuned?

Any help or advice is warmly welcome!

Thanks,
Akos