The Randall Museum in San Francisco hosts a large HO-scale model model railroad. Created by the Golden Gate Model Railroad Club starting in 1961, the layout was donated to the Museum in 2015. Since then I have started automatizing trains running on the layout. I am also the model railroad maintainer. This blog describes various updates on the Randall project and I maintain a separate blog for all my electronics not directly related to Randall.
2025-04-17 - Distant Signal: Turnout T330 Display Indicator
Category RandallI have installed my latest experiment at Randall: the Distant Signal project.
This displays the status of the turnout T330 to the Saturday Operators, using a LED Matrix Display.
The green and red lines show the state of the turnout: normal or thrown/divergent. “T330” is the number for the turnout being shown -- in this case the Sonora turnout, just in front of the train on the video above. The block numbers (B320, B321, and B330) reflect the track occupation as seen by JMRI -- the blocks are yellow when they are occupied.
The display is mounted in a way to be clearly visible for the Saturday Operators when they stand at the Stockton Yard -- that’s the location from which they operate their trains, and from this vantage point of view, it’s impossible to know how the turnout is aligned -- and that’s exactly what this new panel is supposed to clarify:
As explained in the first post about the Distant Signal project last month, the display connects to the main automation computer over wifi. Since it derives the state from JMRI and the NCE Command Station, the display is in sync with turnout changes whether they are initiated by the automation computer or by a user changing the turnout using a NCE controller.
For now, this is an early experiment. I expect changes based on usage feedback.
Eventually, if that’s well received, I would like to duplicate this effort to a few over turnouts which are either hard to view or impossible from the main Stockton Yard location: the Bridgeport turnout, and the mainline to Napa yard turnouts. The Bridgeport turnout is the first one where I added a LED indicator years ago to solve exactly that problem, and it can now benefit from a nicer display. The Napa yard turnout is on the other side of the mountain, and the only way to know its state is to actually walk over there. In this case I’d place a similar display in the Stockton Yard area so that it’s easy to know what’s going on the other side of the mountain.