In message , Peter Masson
writes

"John Rowland" wrote in message
...
Snip
Something along the lines of a transponder at the start of each platform
which is detected by each door and enables the doors on the appropriate
side, and another one at the end of each platform which disables each door.
Other interlocking means that doors cannot actually open until the train has
stopped, and failsafe precautions could cancel the enabling if the train
hasn't stopped within, say, one minute of passing the transponder. Some
complications for platforms on reversible lines, but I can't help thinking
that something like this has the potential for being more reliable than the
GPS technology (Can GPS identify which line the train is on if adjoining
platforms are different lengths?)
Peter


With difficulty, because GPS has an accuracy of +/- 100m, unless of
course you are using Differential GPS, but that is mainly a maritime
system.
--
Regards,

James Christie

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