Re: ARTC Vic Train Control

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

In article <79duf2$ijo$1@news.mel.aone.net.au> dbromage@fang.omni.com.au (David Bromage) writes:
>From: dbromage@fang.omni.com.au (David Bromage)
>Subject: Re: ARTC Vic Train Control
>Date: 5 Feb 1999 05:09:54 GMT

>Ray Gomerski (ELECTROWELD@bigpond.com) wrote:
>> The main reason is for safeworking.  A train order is required at Tottenham
>> for the section from Newport to Manor Loop.  There are no crossing loops
>> between Tottenham Loop SG and Manor Loop SG.

>Why does the end of a section have to be a loop? Why can't Newport be an
>sg block point? The section can then be Newport - Manor Loop. Certianly
>you can't cross at Newport, but you can have follow-on movements.

>If Paisley also became a block point (in preparation for becoming a loop),
>even better. Ditto Elders BP.

>Cheers
>David


Because a driver on SG entering the SG line at Tottenham has to be absolutely 
sure that there isnt a conflicting movement , ie he has to know that there is 
no possibility of an up SG train leaving Manor Loop.
The only way he can know that is to be in possesion of an order when he enters 
the single line section , as the departure home signals at the down end of 
Totty Loop are in no way interlocked with the ASW system.
You could theoretically get a red over green from the down end of No 1 road at 
Totty Loop if there was a train approaching manor Loop with an authority to 
continue on .
This is one of the fundamental weaknesses of ASW and train orders, no 
electronic feedback from track ccts to tell you where the trains actually are.

MD