Some advanced automobile alarms are equipped with GPS and a mobile
phone interface to report their location if stolen. As a byproduct
these can also detect air bag activation and automatically report that
an accident has occurred and the car's location.
The Alaskan rail system uses GPS to locate the train and a digital
packet radio to report it. I suggest the radio could also be equipped
with low cost accelerometers as used in car air bag controllers to
detect a large deceleration, indicating an accident. The digital radio
could then report the position of the train and signal a possible
accident. This could be done very quickly and automatically, in the
event the train crew was incapacitated.
This may seem superfluous, as a control centre monitoring the position
of each train should alert staff to a problem. Also it would be
expected the train crew would report an accident. However, it may be
difficult for the central system to infer the severity of a problem,
and the train crew may be unable to report. An automated alert from
the train showing excessive deceleration would be a less ambiguous
indication of a problem.
Such a system would have been of use in the Waterfall accident, 31
January 2003, as detailed in the "Waterfall Rail Safety Investigation
Final Report" <http://www.transport.nsw.gov.au/waterfall/>. Section
14.3 "Identification of the emergency" describes how the accident was
initially thought to be a track circuit failure. It was approximately
15 minutes before the guard was able to report the derailment and even
then there was difficulty with identifying the accident location for
If the train was equipped with an automated device it could have
reported the accident and its location within a few seconds. Such a
system could continually report the location of the train, report on
the driver's vigilance and act as a remotely scanned datalogger. The
VHF packet radios are relatively low cost (thousands of dollars for a
radio, millions for the network), as they have a long range and
operate on a low data rate. There may even be an existing government
or commercial digital radio infrastructure which could be used.
ps: I am a computer person, not a railway expert, so please excuse me
if this is all obvious (or plain wrong).
> In "A Sense of Place: GPS and Alaska Rail Safety" (GPS World, March 1,
> 2004 <http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=87472>)
> Andrew J. Schiestl describes a system using GPS and VHF radio for a
> collision avoidance system (CAS).
Also known as 'Positive train seperation'.
> The Alaskan rail system uses GPS to locate the train and a digital
> packet radio to report it.
In an urban area the trains are so close together that the collision
warning aspect is useless and GPS does not have suffcient resolution to
identify what track a train is on multitrack lines.
NSW freight locomotives are already fitted with GPS and digital radios.
It's probably only a software upgrade for them to warn each other that
there is another train around, but it's only going to be useful in
country areas - as a warning to 'wake up' the crew that they are
approaching a cross.