Why use relays?

Why not just wire the feeders for those last isolated couple feet of track through switches that will open when the liftout is removed? 

Although, with all the new keep-alive technology out there, I don't think that cutting the power is going to be quite as useful as it used to be. I'm starting to think in the direction of a mechanical block instead. Perhaps you could use those limit switches to run a servo that would lift a pair of strong wires into place? 

Photo sensors?

Jeff's comment is funny but my engines run solely on battery power so maybe a retractable pin would work for me!

Check out Rob Clark, Pierre, or Dr. Geoff's blogs using the Arduino along with photo sensors to disable the sections prior to the abyss. When the section is open the sensors would become active and, if occupied or triggered, could shut off power or, as you suggest, send a DCC stop command to that block. That way the entire layout wouldn't shut down. How to do this is one I'd be interested in hearing about. Battery powered engines get dcc commands via the transmitter so a solution that can send a packet to a specific engine(s) would be really interesting. It has been suggested that RFID chips in the loco or tender could be used to identify the train and dcc commands would address only that engine. 

"my engines run solely on

   Drill a hole in the center of the track and stick a phillips screwdriver in there when the lift out is removed. Never failed to stop O scale run a ways and I always knew where two screwdrivers were......DaveB 

Lift Out Section Wiring

Thanks guys. I forgot about those darn keep alive circuits. Damn.

I actually like Dave's idea. It couldn't be more "low tech", which I always like. Keep it Simple Stupid!

There are two tracks so a block of wood with two pins is starting to look real good!

It's fairly straight forward...

Try using this as a guide, has worked a treat on my layout...

Just beware of keep alive circuits.  Jas...

Keep Alive vs Liftout!!!

l have a swing gate across a door way on my layout and the latch to lock it into position controls the power feed to the gate track and 10" of track on either side of the opening. It works great!

Then someone in there wisdom to move our hobbies technology to the next level, came up with Keep Alive circuitry. This circuitry allows locos to operate on dirty track sections, dead frogs. This circuitry allows the loco, depending on the DCC decoder to keep moving for 3 seconds and more, some for as much as 10 seconds. As a result of this new technology, I can NOT use decoders with Keep Alive, because the will keep moving beyond my 10" of dead track.

I guessing but I think, at yard speed that movement translates to about 5' of travel before it comes to a stop, and more at higher speeds! 

This is something to consider when designing your track work for the lift out!

Ralph Renzetti (CN 6401)

physical barrier

I put a physical barrier in place for my drop bridge across the doorway, mostly because if I didn't one of my kids (or me) will inattentively drive a train into the open gap.

https://forum.mrhmag.com/post/a-different-kind-of-interlocking-system-12199579 is the blog post.

Marc Simpson

Lift Out Section Wiring

Instead of, or better yet, in addition to interrupting the wiring:

Why not a mechanical pin or plate which is held in the up (blocking) position by a spring or counterweight?  It would be pushed down out of the way when the lift-out is in place. 

The electrical solution would prevent most floor dives, but the mechanical stop would add a fail-safe barrier.

Bill B.

N Scaling in south Okaloosa