I'm going to double down on the suggestion of powering the rails simply on account of the fact the main product is VR camera on a train and a web service built

I'm going to double down on the suggestion of powering the rails simply on account of the fact the main product is VR camera on a train and a web service built around it. Reinventing the way model rail systems work from the ground up will get you side tracked. You can always figure out how to construct battery based, wifi enabled smart locomotives later on. There's already a ton of standardization and interoperability in model train building. You don't have to reinvent it unless you insist on avoiding track electrification. That said, if you're really committed to designing from scratch and are looking at the ability to climb steep grades like stairs and chimneys, and if you happen to be in San Fransisco (as many here are), I strongly recommend the cable car museum. Admission is free and its extremely educational. The cable cars are a marvel of engineering. A wholly modern rapid transit built before there was even electricity. The way they accomplished this was by having a cable underneath the tracks that is constantly moving (powered by steam in the main depot). When the cable car operator wants to start moving, they pull a lever which holds the car to a fixed point on the cable (in the exact same manner as the friction brake holds it to a fixed place in the ground). The cable car museum shows in stunning detail how this system accomplished things all the basic railroad operations like turns, tracks crossing, and track switching. You might find some inspiration in seeing how they did it.