Re: [WA] Zanthus collision 18 Aug

[mauried@commslab.gov.au (Maurie Daly)]

In article <aZNS3.4272$YE2.8294@ozemail.com.au> "Ray McDermott" <raymcd@ozemail.com.au> writes:
>From: "Ray McDermott" <raymcd@ozemail.com.au>
>Subject: Re: [WA] Zanthus collision 18 Aug
>Date: Sun, 31 Oct 1999 13:12:34 +1100



>--
>Ray McDermott   raymcd@ozemail.com.au
>Maurie Daly <mauried@commslab.gov.au> wrote in message
>mauried.355.381A88C7@commslab.gov.au">news:mauried.355.381A88C7@commslab.gov.au...

>> Its amazing the spin that can be put on the outcome of an inquiry to make
>it
>> look good.
>> Any "Rail  Safety System" that allows a set of facing points to be
>> reversed whilst a train on a main line is approaching them isnt a rail
>safety
>> system at all.

>Agreed!  AFAIK, all loops on TAR are ftted with power operated points and
>searchlight signals.  I visited the then ANR control centre a few years ago
>and  engineer explained system as follows:
>The searchlight is merely a point indicator:
>Flashing Green = Main
>Flashing Yellow = Loop
>Flashing Red = Points not set correctly
>Trains ordered to take loop let themselves in and out by push-button
>switches. He did not mention track-circuits. I am not sure by what means
>arrival-end points reverse after the train is in the loop.    Simple
>axle-count system comprising  proximity detectors and industrial PLC is used
>to check that complete train is out before resetting departure end points.
>They planned a more elaborate system with remote point operation etc when
>the fibre-optic cable was installed however this was not proceeded with (no
>money?).

>The IP train order would have specified the Main and you can see the point
>indicators from 10 km away at night so I wonder why the driver did not query
>the indication.  There is complete radio communication available on the TAR
>During long cab ride I noted that drivers advised each other of location
>when approaching for a cross.  Seems IP driver must accept some blame.

>Question:  Are Main Line Indicators at NSW crossing loops controlled by
>track circuits as well as points position??

>Ray .


Its somewhat unclear as to when the facing points were reversed.
If the IP was a fair way off from the loop, its quite possible that at this 
stage the points hadnt been reversed and he would have seen the flashing green 
, ie what he was expecting to see.
If the point reversing took place when the IP was fairly close to the loop , 
the driver wouldnt have been expecting the signal to change state ,and did 
what he could at the last minute.
Im not familiar with the rules that apply on the TAR when approaching loops 
where a cross is to occur and the order gives you the main , but is there any 
requirement to slow down , maybe not .

On NSW CTC and most  (all ??) other systems the arrival signals are controlled 
both by the track ccts of both the main and loop , and also by detectors in 
the point machine which senses where the blades of the points are .
Approach locking is applied directly to the point machine so that it cant be 
changed whilst a train is approaching or a train is over it.
Any half decent system simply woudnt have let the points be reversed whilst a 
train was sitting in the loop.
Common sense really.

MD