Signalling Practices for Interlocking (SP Donner Pass)

[kc9jts]

The signals on that particular line (around Truckee as the diagram says) would have been primarily 2-heads at the control points (regardless of number of routes); from what I can tell there would not have been any 3-head signals.  Most of the signals (but not all) would have been searchlights but there would have been some colorlights.  Aspects of course vary by location but intermediates had Stop, Approach, and Clear along with some locations having Advance Approach (flashing yellow), or approach diverging (yellow/yellow) if preceding a control point with a diverging route.  Control points would be about the same other than the addition of diverging approach (R/Y), Diverging Advance Approach (R/FY), and Diverging Clear (R/G).

I don't believe that restricting/lunar aspects were used much in this area but typical SP practice would have been to use a lunar only into a dark track or in some scenarios for a following move into an occupied track (such as a facing move into a siding).

Nick

[jagged ben]

Thanks Nick.

I'm aware we're using quite a bit of modelers license here anyhow.  The actual Truckee is Track Permit control on the main that's next to the station, and there's only those two main tracks.   I've been rebuilding the Truckee section of the layout for a more prototypical feel, but I'm still working with an inherited  track arrangment that would be too much work to completely 'fix.'   Hence we have a track arrangment that I believe SP would have signalled with some three lights if the real Truckee had ever been like it, but it wasn't, so they didn't.  So at a certain point I just kind of dropped consideration of specific signals on the pass.  Considering that with our compressed version of the pass we'd be changing signalling systems every five feet or so if we tried to be prototypical.  And we're also trying to keep the signalling fairly consistent across the layout so it's not too confusing for operators.

[draskouasshat]

Western railroads weren't big 3 head signal users. For the most part it's an eastern thing. I'm not saying they're not our there because I know that are. Just use a two aspect signal. You're making this way to hard. If it's a move through a normal switch point, g/fy/y over red, if the route goes through any switch sitting reverse, red over g/fy/y/fr/lunar. I guarantee you liars were used here if a signal was lined into a dark track or any unsignalled territory or a track specifying restricted speed.

Also, there are signals that most definitely display the next signals aspect or are repeaters that display the next signals complete aspect to keep trains out of areas with numerous crossings where a train sitting would cause major problems.

[jagged ben]

I still think we want a different aspect for crews entering the station than for just crossing over to take the other main.  Crews will actually use these signals to confirm that routes are lined correctly, this being a model railroad.

[draskouasshat]

Yes a model of an operating railroad. Might as well make it accurate and easier to wire.