The speeds called for by the contract with the city introduced motive
power requirements which were unprecedented in any existing railway
service, either steam or electric, and demanded a minimum weight
consistent with safety. As an example, it may be stated that an
express train of eight cars in the subway to conform to the schedule
speed adopted will require a nominal power of motors on the train of
2,000 horse power, with an average accelerating current at 600 volts
in starting from a station stop of 325 amperes. This rate of energy
absorption which corresponds to 2,500 horse power is not far from
double that taken by the heaviest trains on trunk line railroads when
starting from stations at the maximum rate of acceleration possible
with the most powerful modern steam locomotives.
Such exacting schedule conditions as those mentioned necessitated the
design of cars, trucks, etc., of equivalent strength to that found in
steam railroad car and locomotive construction, so that while it was
essential to keep down the weight of the train and individual cars to
a minimum, owing to the frequent stops, it was equally as essential to
provide the strongest and most substantial type of car construction
throughout.
Owing to these two essentials which were embodied in their
construction it can safely be asserted that the cars used in the
subway represent the acme of car building art as it exists to-day, and
that all available appliances for securing strength and durability in
the cars and immunity from accidents have been introduced.
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