Re: Derailment at Concort West - Reason

[McFergus@my-dejanews.com]

In article <897394643.663904@woody.hotkey.net.au>,
  "Michael Walker" <walker@hotkey.net.au> wrote:
>
>
> shouldn't the loco driver take at least some of the blame. After all, he DID
> misread the signal. Or are signals in New Zealand prone to ambiguity?

Let me change the conversation to NSW signals. If I trip up somewhere, someone
please let me know!

The normal sequence that a driver sees for an advance signal at danger
assuming double light four aspect signalling is as follows:

G            G            G            R
G   ----->   Y   ----->   R   ----->   R

And the sequence for a turnout (assuming that the line ahead through the
turnout is clear) is:

G            G            Y  [tn'out]  G
G   ----->   Y   ----->   Y   ----->   G


For a suburban train with good braking capabilities travelling on a line
without a turnout, a driver may reasonably pass a Green over Yellow without
significant adjustment to speed, as depending on signal spacing a suburban
train could comfortably stop in the distance between the Green over Red and
the Red over Red. The Green over Yellow is an advanced warning, and allows
closer headways by giving freight trains with their longer braking distances
enough warning before a danger signal.

Therefore, if you give a driver of a suburban EMU a Green over Yellow, he may
well think that it is just warning him of a Green over Red, rather than a
Yellow over Yellow, unless he can see the Yellow over Yellow ahead (e.g. a
dead straight line with good forward visibility) and continue on at line
speed.

In some locations (e.g. Cabramatta, Merrylands) the Green over Yellow warning
of a divergence is replaced with the normal aspect (the aspect the driver
would get if they *weren't* taking the turnout) together with British Rail
style lunar lights indicating the route the driver is to take. Instead of a
Yellow over Yellow at the junction, they get the normal aspect, with a
dot-matrix letter confirming the route:


           o
            o
             o           |B|
G            G            G  [tn'out]  G
G   ----->   G   ----->   G   ----->   G


Whilst I'm not sure of the signalling arrangement at Concord, it seems that
confusion over the meaning of signals may have been a contributing factor. The
above arrangement would help reduce such confusion.

Regardless, unless the driver showed some sort of intent to cause the
accident, or gross negligence (e.g. being drunk), it is unfair that he should
take the blame. All humans are fallible, and if we are to put drivers in
charge of trains without suitable technological aids (e.g. ATP), then we
should expect a certain amount of errors.

How many people participating in this newsgroup can honestly say that they
perform their own jobs 100%, 100% of the time? If you are a receptionist, you
may accidently photocopy a wrong number of copies of a document. If you are a
postman you may occasionally place a letter in the wrong person's letterbox.
If you are a baker, you may forget an ingredient in a batch of bread dough.
However if you are a train driver, any mistake you make (even when committed
at some ungodly hour of the morning when you are a little on the tired side,
just like the baker) can cost lives.

Drivers should not be held accountable for being human. If we were that
serious about rail safety, we would look at implementing measures such as ATP
to ensure that a 'superhuman' was monitoring the efforts of the human driver.


Rob

Sydney (Australia)

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