Subway Tracks Stationing Data

[Cameron Howley]

Hi everyone, 

TLDR: how does the MTA internally store/handle track stationing data for the whole subway system?

For those unfamiliar, the system used to refer to the location of equipment on or near the subway tracks is called track stationing or chainage, and it consists of a unique name for the track (e.g. B1, C2, E4...) and a footage from some arbitrary fixed point given in the format XXX+XX, so if the track starts at 0+00 and 15,328 feet down the track B1 would be referred to as B1 153+28. This footage is railroad distance, not distance by the most direct route, so it accounts for the twist and turns of the tracks. 

I am curious about how the MTA internally keeps tabs on stationing and track names with how massive the subway system is and how many different lines there are. And if there is a system -- is it proprietary information or is it publicly accessible. If anyone who previously or currently works at the MTA knows anything about this it would be much appreciated. Thanks!