Re: ATP

["MattyQ" <matticue@corplink.com.au>]

mcfergus@my-dejanews.com wrote in message
<7cs732$mf6$1@nnrp1.dejanews.com>...
>For the benefit of the rest of us, could someone please elaborate on the
above
>conversation? I for one would probably find it interesting if I knew what
you
>were talking about!


I will explain what I know of ATP. This is how it is supposed to work as I
understand it but they seem to be having much problems with it at the
moment.

ATP is the Westinghouse continuous Automatic Train Protection system being
introduced to QR's diesel locomotive, tilt train and soon, IMU fleet. It
performs a similar task to the Ericsson Automatic Train Control system
fitted to 3900 class electric locomotives and ICE units.

Both ATC and ATP are cab based computer systems designed to receive
information about the track geography, signal aspects and temporary
worksites etc. and keep the speed of the train in check accordingly. The two
systems differ in many ways. ATC is manufactured by Ericsson and is regarded
as "intermittent". Information can only be fed to the locomotive by means of
track mounted beacon groups. The drivers ATC displays show what speed you
should be doing now and if required to slow down, what speed you must slow
down to.

ATC has proven to be much more reliable than ATP even though it is a more
primitive system. The only source of information to a loco is via beacon
groups. If a loco crosses a beacon group associated with a signal at stop,
the system will force the driver to stop the train at the signal. If,
however, the signal clears after the loco has crossed the beacon group, the
computer will keep the loco under restriction until it crosses the next
beacon group and the restriction is lifted hence the term "intermittent".

The idea behind ATP is that it is a "continuous" system. Track mounted
transponders are placed at strategic locations on the track but only really
hold information on track geography such as curves and stations. In other
words, information which never changes. ATP has a second source of
information which is transmitted to the loco by means of radio waves. This
information is usually parameters which can change and affect the trains'
performance, such as signal aspects. If a signal is at stop, the ATP system
will force the driver to stop the train as does the ATC system. The
difference is, if the signal clears, the on board computer is updated
straight away and the restriction is immediately lifted.

As I said earlier, this is my interpretation of how ATP is SUPPOSED to work.
If I have made any errors, Daryl Georgee may wish to comment.

Regards

Matt Smith
Brisbane, Queensland
Reply to matticue@hotmail.com

You can't slam a revolving door.