Tonnage Rating of Locomotives

nw-mailing-list at nw-mailing-list at
Wed Aug 2 14:37:47 EDT 2006

Up until about 1970 BC (means before computers), tonnage was calculated
by a "number dummy" (read clerk) adding the net weights of the loaded cars
(shown on the consist in tons) and assigning a tare weight of 24 tons for
every car in the train. As information, Southern Railway calculated the
tare (railroaders call it the light weight) weight as 22 tons.

There were many inaccuracies shown in the gross tonnage a train was
moving. If a car hadn't been scaled, an estimated weight was used. In
one instance on the Virginian, a fill had been added, but it wasn't added
to the consist, so the train left with more tonnage and more cars than
the crew knew. In later years, using a tare weight of 24 tons grossly
underestimated the weight of a train. In one instance, the Planning
Department attempted to simulate the operation of an empty train of
covered hoppers across the Fostoria District. When the bona fide
movement did worse than the computer simulation, investigation revealed
that although light weighs were calculated at 48,000 lbs., the actual
light weight of each covered hopper was around 60,000 lbs. In
calculating tonnage today, the computer goes to the UMLER file and
inserts the correct light weight.
Harry Bundy
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