Branch signaling continued

[NW Mailing List]

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