Re: Question re: overlap

[signal_engineer <hayesipNOhaSPAM@yahoo.com.invalid>]

David Johnson <trainman@ozemail.com.au> wrote:
>I have a question, aimed mainly at Ian:
>
>On the Y-Link (Harris Park - Merrylands), the home signal is
the only protection
>for the points - there is only one stop signal, being the home,
and no
>catchpoints.  If a train was to be approaching Merrylands from
Harris Park at
>track speed (50), and pass the home at stop, it would probably
go far enough to
>foul the down old south.    Why is this protection set up this
way?
>
>--
>David Johnson
>trainman@ozemail.com.au
>http://www.ozemail.com.au/~trainman/
>------------------------------------
>These comments are made in a private
>capacity and do not represent the
>official view of State Rail.
>C.O.W.S. Page 11.
>
>
>
>
Hmmm, I'm not intimately familiar with the Y-link layout as it
was designed by RSA Signal Design (after I left them) and the
SSI and signalling was installed by GEC-ALSTHOM (now Alstom) our
competitor. Having said that, I can only assume that to set a
route up to that home signal would require the points be set
reverse in order to provide a valid overlap of the signal in
rear. Ordinarily that is not desirable as it could tie up the
junction (setting points reverse) however it could be worked
into the timetable. Other than that there could be a delayed
clearing of the aspect. If I could get my hands on the control
tables for Granville I could give you the exact reason. Sorry
but at this stage I'm only guessing.

regards Ian
Signal Design Engineer



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