Extra trains are not scheduled in the timetable, have no class, and
hence have no superiority.
When extras are moving without train orders
other than the ones that created them, they are said to be "operating with
respect to the timetable."
This means that they are adhering to the
provisions of rule S-87, by clearing the main track for trains scheduled in
the timetable.
When it is impossible to clear the track for a superior
train, the rules require that the train be protected against the movement of
other trains. To do this, a flagman is sent in the direction from which the
train is expected to flag it to a stop. On double track, one is sent to the
rear; but on single track, one must be sent to the front as well as one to
the rear to stop any trains. Rule 99 is the rule requiring such protecting
or flagging.
Proper clearing and clearing without delay are said to be
accomplished when the trains being cleared are not stopped or delayed, as
paragraph 1.4 explains.
If all extras on single track could always operate with respect to the
timetable only, the subject of train dispatching would be much easier to
understand. An extra train, after being allowed to move out of its starting
yard, would proceed on its way until the timetable, rule S-87, and the
crew's watches told the crew to "take siding."
After the superior train
passed, the crew would again consult the timetable.
They would know the
exact distance to the next siding, and the approximate number of minutes it
would take to reach there.
If the crew could make the siding without
sticking--delaying--a superior train that was close, they would proceed. If
they lacked sufficient time to clear a train in either direction or had the
least doubt that their train could clear in time, the crew would remain
where they were until they did have enough time. Thus, an extra train would
travel over a division in stages, heading into a siding when necessary and
remaining until the superior train passed. It might then possibly pass up
the next siding, and perhaps enter a third, to clear one or more scheduled
trains in either or both directions.
The method just described is cited primarily to show the principle of
extra movement, but it seldom works out in actual practice. The reason for
its being more theoretical than practical has not been taken into account:
the extra trains that may be, and generally are, operating in the opposing
direction. Regular trains have no way of knowing about extras, and extras
ordinarily do not know about other extras in the same or opposing direction.
Therefore, they are advised of the presence of opposing extras by the
dispatcher's train orders.
When operational difficulties occur, the
dispatcher's train orders affect scheduled--superior--trains. A
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