> 1. Is there such a thing in CTC - seems they
> aren't 'controlled' (so they would be a 'gap' if
> in the middle of an otherwise CTC route?)?

Keep in mind that regardless of the modern signal system, they are supposed to be designed as "fail safe" so there are safeguards designed in to prevent a conflicting movement to be authorized by signal. In CTC/TCS, the dispatcher can only request that the system clear a signal for movement, the actual on-site signal circuits have the final say to display a proceed signal.

To the best of my knowledge, for a diamond/at grade crossing in CTC, the dispatcher must request that the signal clear for movement on any route.

>
> 2. Are any being integrated with PTC - or are they
> even still an 'automatic' once that's done?

They would have to be integrated into PTC, assuming the line crossing the diamond was PTC equipped. That doesn't do any good if the other route/line doesn't have PTC, but that was the reason some were equipped with derails or smashboards in the first place.

>
> 3. How common are these in the west anymore /
> examples?

I've had to deal with plenty of them in various places I worked. Usually they aren't much of an issue. Get a distant clear, blow on through. Get a distant approach, stop at the diamond and wait your turn. The one I hated was at Erskine, Minnesota. Minnesota Northern had bought a bunch of BN branchlines, a combination of former NP and GN. The MNN operated out of Crookston, and had two different branches south out of there. They had trackage rights on the BN main east to Tilden Jct where there was a short branch to the north to an active gravel pit. Tilden used to be a crossing - you could see the footings for the pipeline on a manual interlocker. From Tilden the line used to go to Thief River Falls and further north to Warroad, but a trestle over a river was failing due to soft ground. Instead, BN arranged for trackage rights on the Soo Line from the diamond at Erskine to Thief River Falls where they could get back on the original line.

The problem at Erskine was the connector was not only an active interchange bu connected off the BN in the wrong direction to the south on the Soo. So when you got to Erskine, if you had a short train you could get just over the diamond, shove the interchange track back, take the connector, clear your BN warrant and get a Soo warrant, pull out on the Soo, shove across the diamond and run around your train on the Soo side. But - if you had a unit train - it got real interesting. You had to hold a warrant for both BN and Soo, and often make multiple moves across the diamond. We usually had a floating brakeman in a vehicle to deal with the rear as far as switches and crossings. It wasn't unusual to end up with 4 engines in the middle of 100+ cars trying to do all this, and in the meantime you've got both railroads tied up.

The problem with automatic interlockings is that they get confused if you try to do any switching over them. There is a pushbutton that might get you clear signal, otherwise you have to wait so many minutes before flagging the crossing and making your move. Even though we usually held a work between on both routes, there was no provision to allow us to ignore the signals and simply stop and proceed at restricted speed. We were joint with a Soo mainline local once that did confirm by radio we were going to stay stopped and went through the crossing, but they had job insurance. Nothing unsafe about that, the rules just didn't cover it.