[IshKebab]

Do trains have real time position sensing and reporting now? Feels to me like that should be something that could (and should) have been done 20 years ago at least. You don't even need GPS - even wheel-based odometry should work very well. Visual odometry can be used to detect wheels slipping if necessary. Hell you could probably count sleepers.

[greengreengrass]

I believe some Tube stock uses wheel revolution counters to track where the train is and trigger announcements, although a lot of signalling will be going over to using balises to tell the trains where they are (if not already) and to provide supervision.

[waiwai933]

Newer fleets will have GPS units on board that report back to Control, but it's not universal and I don't believe there are industry-wide standards or APIs. Signalbox is definitely extrapolating from TD/TRUST/Darwin, not GPS reports.