swt_passenger
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- 7 Apr 2010
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Do some ASDO systems not work with beacons so that the train "knows" how long the platform its sitting in is?
They might not be a sophisticated as that, I've no first-hand experience of them.
Yes they can. That's how the system recently fitted on the SWT network does it, there are passive devices (known as 'balises') in the four foot at all platform entries that the train reads by wireless, so that it knows which station the train is in, which platform and the direction of travel - because operational lengths can vary by direction of travel depending on signal positions.
An earlier ASDO system used on Southern generally uses GPS to define the station location, with beacons added as an extra when there's a need to define individual platforms as being different lengths, or when the GPS is obstructed.
In the SWT trainbourne equipment, the 450/444 ASDO is combined with the Train Management System, (TMS) and the system still relies on the driver stopping at the correct mark, as only the leading cab reads the data. In the older 458/5s though, the ASDO system is separate to the TMS, and every individual carriage has a reader, so the scheme on them is that all carriages that pass the balise have their doors opened.
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