The Elixabeth Line runs 24 trains per hour automatically through a 10-station tunnel in central London. It mainly uses axle counters to measure where the train is.
> The signalling is essentially hands off and is timetable driven. The latter includes GoA3 reversing moves at Paddington and Abbey Wood which are fully automatic as are all entries into and out of a depot. The line uses axle counters for secondary train positioning information other than where neutral sections for the overhead power exist, where track circuits are deployed, these being seen as less vulnerable to any spark interference from the overhead catenaries.
But it’s not an odometer. It’s a sensor on the track that counts axles. The system knows the precise location of the sensor, and how far axles are spaced.
That's interesting. Do you know if they are used to keep track of the trains' positions with axle-spacing precision everywhere, or only at stations and track-section boundaries? (my somewhat cursory search suggested probably the latter.)
I don't know for certain, but they'd have to have at least one set on both tracks in each ventilation section, to enforce ventilation rules (read the rest of the article about the tunnel's ventilation management). It also points out that axle counters can sense backward movements, should a stuck train require the ones following it to reverse out of the tunnel
https://www.railengineer.co.uk/controlling-the-elizabeth-lin...
> The signalling is essentially hands off and is timetable driven. The latter includes GoA3 reversing moves at Paddington and Abbey Wood which are fully automatic as are all entries into and out of a depot. The line uses axle counters for secondary train positioning information other than where neutral sections for the overhead power exist, where track circuits are deployed, these being seen as less vulnerable to any spark interference from the overhead catenaries.