Branch signaling continued

NW Mailing List nw-mailing-list at
Wed Nov 13 09:47:57 EST 2013

On 11/13/2013 7:28 AM, NW Mailing List wrote:

> Although, sometimes depending on the location and signal setup, it's quite possible they would skip the advance approach and go straight from clear to approach diverging.

Unless there was a short block involved, there would be no "Advance
Approach". You would go from "Clear" to "Approach Diverging" (SOP).


> The way you wrote it is wrong, because when the train gets an approach diverging, the expectation is that the train would take a diverging route at the NEXT signal. If a train gets an approach diverging, then an approach, the lineup was changed.

As the dispatcher has no idea what intermediate signal the train
has last passed (the "Approach Diverging" could already have been taken
(passed) and the possibility of being too close to the control point to
safely stop), in order to change the aspect of a control point that has
already been lined, he would first have to call the train and have him
stop and the train, tell the dispatcher that he is indeed stopped and
give the dispatcher permission to change the signal. I have had this
happen many times. The exception to having the train stop would be a
clear understanding between the engineer and dispatcher that a signal
change is wanted by the dispatcher and the engineer confirming that he
is far enough away from the signal that is to be changed so that the
train can be safely stopped before that signal. The reason being that
the signal to be changed will have to be coded "Stop" first and that it
needs to "time off" before another favorable signal can be displayed.
Another exception would be if the train is far enough away from the
signal to be changed that it has other control point/s between the train
and the signal to be changed, the dispatcher will know that the change
will not effect the movement of the train.

Jimmy Lisle

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