response has been given, the order to the superior train becomes a holding
order and cannot be delivered until it has been repeated and completed.
Suppose, for example, that the power failed after the order had been
copied but before it had been completed. The "X" response has already been
given and a copy of the completed order to the inferior train has already
The inferior train would execute its part of the order.
However, the superior train could not pass the office holding an order for
it which lacked the dispatcher's final approval. The operator would set a
train-order signal against the superior train and cause it to stop. Even
then, when the operator and the crew knew the contents of the order, the
crew could not act on it. Flagmen would have to be sent both forward and to
the rear of the waiting train until power was restored or until the
dispatcher could get additional instructions to the operator holding the
When a train prepares to leave its starting point, the crew has no way
of knowing whether all superior trains have arrived and departed. Neither
has the crew any way of knowing whether any superior trains that have passed
were displaying signals for following sections (par. 4.7).
localities, the dispatcher advises a crew by a form R order of the superior
trains for which they must wait before going out on the main track.
other locations, train registers are maintained to furnish this information
for all concerned. When a train arrives at a station where it has work or
when it reaches a junction point, the conductor signs the register.
writes in the number, class, and arrival time of his train, and the type of
signals it is displaying, if any.
Just before the train leaves, the
conductor checks the register for other arrivals or departures that may be
superior and then enters his departure time. Generally, extra trains having
no stops where the register is located are not stopped simply to register,
and timetables of most railroads provide that they may register without
stopping. Instead, the crew throws off a message containing the necessary
information and the operator enters it.
Information from the register is conveyed to a passing crew in the form
of a train order which might read as follows:
Extra 198 West
All Superior Trains Due at RK Before 2130 Hours
Have Arrived and Left