Signals and CTC were not prerequisites for PTC on the railroad that runs past my house on its way to the Canadian border.

In 2011, UP's AVP-Transportation Systems gave a presentation at the UPHS convention in Spokane. He said at that time that about a dozen wayside appliances for PTC had been installed on the Spokane Sub (former Spokane International) between Spokane, WA, and Eastport, ID. Plus several UP and CP units had been equipped with PTC gear.

The Spokane Sub was specifically chosen as an early candidate for PTC implementation and testing because of two criteria: it carries a high volume of TIH hazmat traffic, and it's mostly dark/TWC territory. Over the years since 2011, PTC antennas have sprouted up at turnouts throughout the Spokane Sub, and in-service testing and use of PTC has been ongoing (though not without its challenges due to software and other issues).

CTC now reaches from CP Lee Street in Spokane north to the new siding at Garwood/Chilco, ID, which is now getting the final touches of ballast and surfacing. Still dark/TWC from there north to the border. Might be worth noting there are signals in the dark/TWC zone for approach to the BNSF diamond in Sandpoint and for a slide fence just north of Bonners Ferry.