Thanks traveler a lot for your response. I thought defining each service as a shipment is a bit overkill and I was thinking about defining for each vehicle (e.g. veh1) a number of vehicle_routes (e.g. veh1a, veh1b, veh1c…) which are essentially the same vehicle except that there are hard constraints requiring:
veh1a.end <= veh1b.start etc.
but I don’t know where/how to start. I would appreciate if anyone has any suggestion. Thank you.