I'm not really seeking a master kill switch here. I have one of those. The way it went down was, the layout was off and I turned it on. Because the trains are parked with only a couple of car lengths between them, if one takes off there isn't enough time to react. It's like tailgating with your car. I flipped the power off as soon as I heard it move, but it was too late.
The original question was not about modifying the layout, it was about modifying the engines to disable conventional operation. I.E. TMCC only.
Back in the days before TMCC, I wanted my trains to run forward only, because I was using relay controls to start and stop trains. The old mechanical e units were OK, but the electronic ones were problematic because, even after they were locked, they would occasionally "forget" and begin to cycle again. The ultimate solution was to remove them, and hard wire the engines to forward only.
This is really just a high tech version of the same issue. Somewhere on the control board has to be circuitry that detects if there is no TMCC signal. There are switches to turn odyssey and sound on or off. Why not conventional off?
