CTC 'Call-On' switches

[NW Mailing List]

A road crew was unlikely to know a signal had been fleeted. A dispatcher could fleet a signal for his own convenience when he knew he wasn’t going to need to line up any conflicting moves. Set the signal on fleet and it would automatically clear for the next train in the fleet (hence the reason for the term “fleet”) without further action on the dispatcher’s part. Very useful when a number of trains were coming in short succession all doing the same thing so a train wouldn’t have to stop because the dispatcher was busy with other things and hadn’t lined up the next train.

Another reason for fleeting a signal, although this time by a signal maintainer under dispatcher authorization, would be to deal with signal or code line failure. A maintainer could locally fleet the signals so trains could move although without ability to throw switches or allow conflicting movements.

-- 
Larry Stone
lstone19 at stonejongleux.com





> On Apr 22, 2017, at 8:35 PM, NW Mailing List via NW-Mailing-List <nw-mailing-list at nwhs.org> wrote:
> 
> Joe,
> 
> 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:
> 
> https://acm.jhu.edu/~sthurmovik/Railpics/Towers/TOWER_A5/TOWER_A-5-console-unit-levers.jpg 
> 
> 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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