Without getting too complicated about logistics, I find that simply putting railheads and dumps onto the table gives decent appreciation of why breakthroughs are so devastating to an army. Marauding enemy finds itself amongst a rich array of depots stuffed full of goodies, and the disrupted army finds itself similarly short. Modelling opportunities for NAAFI, PX and soup kitchens abound.
You can see below a schematic representation of the chain from the railhead on the left of the picture through to the fighting troops on the right. I just run the trucks in a line between the depots to mark out the logistic routes used for supply. For a division of perhaps 10 fighting vehicles, suddenly having up to 20 trucks in a logistic tail gives a better appreciation of why modern armies are perhaps not as nimble as we would all like to think. The yellow lettering above the trucks lists the German designation for the transport columns and the green lettering below the dumps gives the level of depot. Depots can be co-located if roads are sparse.
Full marks to Tim Gow for spotting that there were not enough trucks in the picture above. Each division should have its own transport companies as well as the corps level transport and army level transport shown above. The labels below of ‘A’ and ‘B’ echelons apply properly to battalion level units, not divisions as we see here.