Another hint is to send each Steam train ONLY to Bobby. Those trains will finish in 2 hours. If, on the other hand, you are tempted to send a train to Bobby and to friends or other contractors at the same time . . . the train will not come back until the LONGEST round-trip.
I try to send enough trains to finish in 10 round trips or so. So for this Bobby mission, I sent 10 small Steam trains. Since I don't care how much material I send (because Bobby does not care what the cargo is) very small trains and then (if I need to conserve raw material) I send just the minimum cargo. The XP wagons are ideal for this because you get more experience per round trip. Also, you are not using up cargo you might want to stockpile at home for a later mission.
This is a good time to dispatch train SETS that use wagons that are NOT REWARDS. Wagons that are REWARDS do not count against your storage limit. To avoid running out of storage space, strive to put wagons that are not rewards onto trains whose cargo does not matter.
