Re: Beresfield Accident Findings

[matthew@mail.usyd.edu.au (Matthew Geier)]

David Johnson <trainman@ozemail.com.au> writes:

>MarkBau1 wrote:

>> Really? Would you mind explaining this system? Are you sure you were not just
>> reading a TRAINS magazine article about a proposal? To my knowledge no such
>> system (or the technology required to implement it) has ever existed on a US
>> railroad! Are you getting confused with L.A.R.S?

>It would be extremely simple to implement.  Whilever there is radio
>communication, this is possible.  Freight Corp's new train radio system will
>allow the controller to see an upcoming head-on collision via the GPS.  If the
>radio system was designed correctly, the controller should also be able to stop
>both trains.

 There is a pilot project online in the US that uses an 'overlay' radio system
and servers to plot all the trains via GPS location. If the system thinks two
trains are getting to close it warns both the dispatcher and the train. If
there is no acknowlegement from the trains, it issues a stop order and the 
oboard computer shuts down the train. The system comes under the name of
PTS (Positive Train Seperation). There are a number of different implementations
being trialed.

 Such a system might have prevented Beresford, but with the train density 
in the lower hunter, the system would be issuing warnings all the time. The
lower hunter is intensively signaled alredy, using transponders the existing
indications could be relayed to the cab, and acknowlegement enfored. Probably
pretty much the same cost as fitting trip arms to all the signals and
locomotives. 

 PTS might have prevented a number of accidents on the TAR, although Hines
Hill it couldnt have prevented. The trains were supposed to cross.  The PTS
server cant know that the tail end of a train isnt away, and even if it was
fed occupancy data from the loop, it would be throwing the crossing train
into emergency, when the other train still has some time to get clear. Some
things still need to be left to the judgement of the crew.