Re: "lost" trains

[John Dennis <jdennis@mpx.com.au>]

On Fri, 07 Jan 2000 03:58:15 GMT, Michael Kurkowski
<mk@netstra.com.au> wrote:

>The GPS unit is a reciever only. From what I know (And I am far from a GPS 
>expert) it will recieve signals from multiple satellites at the one time 
>measure the doppler shift to determine it's location. The beacons may also 
>play a part in this, for a more accurate result. The beacon can't tell 
>which track a train is on, the beacon only transmits the time signal which 
>the GPS recieves and calculates accordingly, according to above. 
>
>You can however, combine track circuits to a telemetry unit which will tell 
>tell the unit in the train which track it's on. The train's computer can 
>then put two & two together, and send which track is on, combined with it's 
>GPS co-ordinates, including speed, and just about any information that you 
>want. For this to happen however, radio communication between the train and 
>reciever, being either the signal box or central control has to work with 
>no break whatsoever.
[snip]
>For the small benefit that you get out of GPS (exact location, exact train 
>information, ability for a controller to view real time log information) is 
>it really worth the extra expense?

A couple of years ago I was working with a software company in Perth
who, amongst other things, were running the system monitoring the free
bus service around the city centre.  Their computer system was able to
determine where each bus was, and transmit signals to each bus stop
advising how many minutes until the next bus arrives.

They also have provided GPS-based systems to (at least one) sugar cane
railway in Queensland, where if a collision is imminent all sorts of
sirens, etc, go off in the loco cabs.

I think that modern GPS systems could be used as an aid to safeworking
on mainline railways.

Cheers...JD

==========================================================
John Dennis                             jdennis@mpx.com.au
Melbourne                                  denjo02@cai.com
Australia                   Home of the Dutton Bay Tramway
DBT URL:  http://members.optusnet.com.au/~jdennis/dbt.html