So here’s a funny one: each time the Saturday operators use the Richmond Yard, the Mainline automation totally goes berserk and fails. Upon examining the logs from the automation computer, I noticed that some of the mountain blocks were seen as active even though there were no trains in the mountain. What’s going on here?

As a reminder: the automation uses current-sensing block sensors. A block is deemed occupied by a train if there is current flowing through that block. The sensors are located on the mountain panel, one per block.

The Richmond Yard and its panel. Mountain division is in the background.
They are not far away yet both should be totally isolated from each other.

This happened twice, and we narrowed it down to only two of the mountain blocks becoming active -- blocks B340 and B360 seen as active -- these are the ramp up and the curve before Summit on the Mountain. Basically the automation thinks there are trains at odd places and goes into error mode. Hilarity ensues. This happens when we have any train consuming power on the Richmond Yard. It’s enough for the trains to be sitting in the yard and not moving.

The yard panel has a power selector for “Cab 1”, “Cab 2”, and “Valley” DC input power. That’s a remnant of the DC power scheme of the layout and we don’t use anything but “Cab 1” for the DCC. To try to isolate things, in the terminal block behind the panel, I disconnected “Cab 2” and “Valley” since we don’t use them:

I tried to trace the “Cab 2” and the “Valley” wires and quickly lost my way. It’s not clear to me where they are coming from.

“Cab 1” is easier because it goes directly to the DC / DCC relay nearby:

And this one is, in turn, connected to the DC / DCC relay from the Branchline. This is as expected as they are both on the same circuit breaker -- which, again, is an isolated circuit not connected to anything on the Mountain power district.

The Richmond Yard has two power supplies and we don’t use the other part of the yard so I disconnected everything there:

Nothing seemed amiss immediately, but it’s not the first time that disconnecting something “apparently” unused has unintended consequences. Looking at you, Mountain Panel 1.

For now I just cannot find a connection between that panel and the blocks on the mountain. I wonder if somehow they are sharing a common ground when they should not. I’ll continue investigating later, and this time trying to trace wires from the mountain towards the yard.

In between, the immediate workflow is to leave all the track unpowered in the Richmond Yard, and turn off the automation before getting a train in and out. That’s ok since that’s already more or less what the Saturday operators do. I updated my “written notes” on the panel to remind operators as such:

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