CTC 'Call-On' switches

NW Mailing List nw-mailing-list at nwhs.org
Sat Apr 22 21:35:16 EDT 2017

I am not familiar with road crews getting "fleet" signals, and rather doubt they did, but I do know that on the switching leads on both ends of Roanoke Terminal yard crews performing a lot of switching moves would request the dispatcher to set the signals on fleet. When the engine passed a signal, then reversed movement on the lead, when they cleared the circuit in the opposite direction, the signals automatically set back up for the crew to continue working by it. The crews "had" the signal until they released it back to the DS, or until the DS asked for it back.

It eliminates a lot of radio traffic plus saves time since the crew doesn't lose any time trying to contact the DS every time they need the signal.
Jeff Sanders

      From: NW Mailing List <nw-mailing-list at nwhs.org>
 To: NW Mailing List <nw-mailing-list at nwhs.org> 
 Sent: Friday, April 21, 2017 6:44 AM
 Subject: CTC 'Call-On' switches

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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