Automatic Train Control

If it were me for TMCC/Legacy equipment I would use software instead of hardware.  More specifically, instead of interrupting power to the approaching block I would send a command sequence to throttle down the engine entering the approaching block to zero using the TMCC/Legacy Protocol sent by a computer (which could be a PC, or an Arduino, or a Raspberry Pi) fitted with software that:

1. Is programmed with the TMCC/Legacy protocol in order to know what commands specifically to send
2. Is connected to a command base (Base 1, 1L, 2, or 3) in order to get the commands transmitted to the layout
3. Also watches the block ahead of the approaching block to detect when it's occupied (this block will need a Lionel SensorTrack, or, if you're handy with wiring, some block-occupancy hardware wired into the computer to do this, perhaps an Lionel 153IR or equivalent MTH IR detector)
4. When a stop is necessary in the approaching block, this software sends a command sequence mimicking pushing the buttons "ENG" and "XX", where "XX" is the TMCC/Legacy ID for the approaching engine, then it also sends the command sequence to that engine equivalent to manually turning the big red knob down to zero speed
5. The only tough part (moderately) in all this comes because this software must know and track each engine, and its respective ID ("XX"), as it goes around the layout so that it knows precisely which ID to send when the corresponding engine enters the approaching block; get this wrong and the approaching engine will not stop but some other engine moving somewhere else on the layout will (if it has that 'wrong' ID)

This is a simplified description, but probably more than you expected, especially if you're more of a hardware person than software, however it's not hard.

Follow the steps in reverse once the lead block clears to restore movement to the stopped engine in the approaching block, i.e.  when a resume is necessary in the approaching block, this software sends a command sequence mimicking pushing the buttons "ENG" and "XX", where "XX" is the TMCC/Legacy ID for the approaching engine, then it also sends the command sequence equivalent to manually turning the big red knob back up to its previous speed setting

Does this approach sound doable to you?

Mike

Thanks for the info Mike. It looks like I'll just be using my Postwar on that loop. LOL. I know a little bit about programing an Arduino but this sounds way above my pay grade.