Re: Train Accident in Blue Mountains

[billboltonREMOVE-TO-EMAIL@computer.org (Bill Bolton)]

"Dave Proctor" <daproc@spambait.umpires.com> wrote:

> And this was clearly either a SPAD or a faulty signal.

Since there are numerous reports that the driver phoned in, as
required by regulations, after stopping within 30m metres of the
signal as it was a danger, its clearly not a SPAD.

> So you are saying that it is not the case that reducing the level of safety
> from what is possible makes for an unsafe system?

Yes, that's what I'm saying.

All sorts of things are "possible" but may not be realistically
implementable under any given set of circumstances.  Railway
signalling has always been a trade off between the "possible" and the
affordable.  That's why so much of Australia's rail track is not
continuously signalled.

> If a level of safety is possible, anything less than that is unacceptable.

Again, this is clearly not the case for most railway signalling
systems in Australia, never has been and probably never will be.

> And your point?

The driver would have tripped through the signal with a short movement
from stand at Glenbrook platform.  ~35 metres would have had an
insignificant effect on the speed of the train ~1.3 kilometers or so
down the track from the signal.

> So you made the point above that the train would travle about 20 metres.
> Tripping through would have stopped the train 50 metres from the station.

No, it would have stopped it probably 5 meters or less past the trip
stop.

> Given the time for the brakes to reset

How long is that?  From observation it seems to be less than 20
seconds on suburban trains.

> it is highly possible that the train would have been going *much*
> slower when the driver saw the IP

By what reasoning do you come to that conclusion? It doesn't seem
"highly possible" at all given the circumstances as we know them now.

> since he would have been starting from 50m closer to it.

35 metres or 50 metres in ~1.3 km is still an insignificant
difference.  Similarly. given that the IP was just starting its own
cautionary move past a signal at danger at low speed, 20 or even 30
second in time is unlikely to have made any difference.

Also if the signal was trip equipped, its my understanding that it
would have been unlikely under the present regulations that the driver
would have had to call the Penrith box, so *may* have completed the
necessary standing time plus trip through quicker than the phone call
and return to the cab actually took.

> So let me get this straight. A train that trips through a signal 30 m from
> the end of the platform, and travels 5 to 10 metres after tripping through,
> therefore coming to a complete stand 35 to 40 metres from the end of the
> platform, will be travelling at the same speed a few hundred metres further
> down the track as a train that was constantly accelerating from the time it
> left the platform. Yeah, right......

Where did you get the "constantly accelerating" and the "few hundred
metres" from?  Neither is supported by reports of the accident to
date.

Cheers,

Bill