Scale test cars were ‘rear riders’ and had a speed restriction (25 mph I seem to recall). Needless to say the operating department wasn’t thrilled with moving them. When I wrote the Iron Mountain book I seem to recall the MP/IM having over 100 track scales. During my career we did our best to eliminate static scales and wrote business rules to use the hump scales. Some of our static scales were built when 40’ cars were the norm so larger cars had to be double weighted (double drafted) by placing the trucks on the center of the scale and the scale master (a railroad clerk) adding the two gross weights together. Besides railroad scales the test cars also were used to certify customer track scales. Scale tickets noted the gross, tare and net weights and any weather conditions as rain or snow would make the gross weight heavier and the shipper could ask for a reweigh.

Some commodities like molasses and tar were weighted loaded and then empty as all the contents couldn’t be completely unloaded due to clinging into the interior of the tank car. The consignee was given ‘commercial consideration’ by the shipper for the material that remained in the car. Where the ‘empty’ net weight was subtracted from the loaded net weight.