CTC 'Call-On' switches

NW Mailing List nw-mailing-list at nwhs.org
Thu Apr 20 17:42:28 EDT 2017

Jim Cochran wrote:
> My assumption would be that there were special controls on the board for
> these locations that would allow the dispatcher to set the signal to
> Restricting overriding the occupancy signal.  If this is the case does
> anyone have/know of photos/diagrams of boards showing this facility?

Here is a non-N&W example of a board with a few "Call On" buttons from
off the web:


I presume the N&W boards would be functionally equivalent.

I believe the action order would be top-down - set the switches, line the
signal, press the call on button.

(The 'Fleet' switches in the picture are used for automatically lining
following trains through on the same route (based on standard ABS behavior)
without the dispatcher having to set the switch for each train. Useful in
certain high volume corridors, but I'm not aware that N&W ever used such.)

Joe Shaw
Christiansburg, VA

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