A couple of things need to be fixed this this with the resupply system.
Here my List
Train & trucks go slower!
Train & Trucks need to be easly killed
Train & Trucks, should be damaged if Rail or Road in bombed. This bomb damage will take the train or truck one trip to repair. Unless a C47 drops goons to repair the track. This will enable bombers to bomber the rail way, with oww lets say 20 250lb bombs and the train will require 20 trips to repair the current line.
Just a thought