g. Doubleheading trains or using pushers. If you use two of the
locomotives for each train, as in doubleheading, the GTL is 1,196
short tons which you find by adding the GTL for each locomotive. If
you were using steam locomotives, you would use only 90 percent of
the combined GTL because this is the efficiency that steam
locomotives retain when doubleheaded.
2.12. NET TRAINLOAD
The payload or actual weight of freight a train carries is the
net trainload (NTL). It is the difference between the total weight
of the cars under load and the same cars empty, or the gross trailing
load minus the weight of the empty cars. Military planners do not
total the weight of all cars in a train and subtract, but rather
assume that 50 percent of the gross trailing load is payload. Using
the example presented in the preceding paragraph, the GTL for a
single 0660 dieselelectric locomotive is 598 short tons. The net
trainload for that locomotive on that division is 50 percent of 598
short tons or 299.
If each train carries a net trainload of 299 short tons, you
find the total number of payload tons or net division tonnage that
can be moved over a rail division each day by multiplying the NTL by
the number of trains that run over the division each day. The
following paragraph explains how to determine just how many trains
you can safely operate.
2.13. TRAIN DENSITY
The number of trains that can be safely operated over a rail
division in each direction during a 24hour period is the train
density
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