Modeling Fill Tonnage.


Active Member
Nov 8, 2001
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I thought we would take a quick look at modeling fill tonnage.
First what is fill tonnage? Fill tonnage is extra cars added to a trains consist to bring it up to full tonnage.This is done for for movement of cars and to keep locomotive house power ratio to train tonnage.This why you may see empty hoppers or pig/stack cars in a general freight train or (say) a cut of covered hoppers in a coal train..
What type of cars is fill tonnage?
1.Empty covered hoppers,boxcars etc needed on another division.
2.Empty hoppers going back to the mines.
3.Empty stack/pig cars.
4.Empty or loaded foreign road cars.This will keep the old per diem charge down.
5.Loads that could not be added to a earlier train due to the consist of that train exceeding the tonnage limit if these cars was added.
So,if our model train has more horsepower then cars according to the train make up switch list then any extra cars we have going east or west can be added to that train by simply adding the car card and waybill if its loaded or just the empty car card to the train consist packet.


Active Member
Dec 30, 2000
Larry brings up a great subject that is generally ignored by modelers. This is largely a transition era phenomenon. Today's modern railroads don't operate with the same rigidity of the earlier era and are much more flexible because of it. (What they do with that flexibility is another discussion thread entirely, however.) The policy on fill tonnage varied from railroad to railroad and even by division on a particular line. The Nickel Plate, which built is reputation on speed and service, would be keenly aware of the tonnage rating for each locomotive on each train and would operate well within those limits to maintain a tight schedule. This would result in a number of fast, short trains across the system with a minimal number of fill tonnage added. A marginal railroad, like the Rock Island of its last two decades, would literally pull whatever cars were going out with whatever power was available. This would mean that a priority train on another railroad would be relatively short while the same train on the Rock would be filled out with whatever junk was going the same direction and probably be very underpowered. I've seen photos from the 1960s where the Rock would operate regular intermodal cars on the end of its passenger trains. While some railroads would do this as a way of handling express packages on passenger trains this was decidedly not the case on the Rock Island. Modern railroads, with their less rigid operating policies, utilize this practice less. The hottest priority trains are never filled out with other cars because the less that can go wrong with them en route the better off they are. On the other hand, many modern railroads under power most of their trains by the standards of old simply out of economy. Since there is no need for the vast majority of what travels by rail to get there in a hurry the railroad is less inclined to get it over the road in, what most railfans perceive to be, a timely manner.