*This is a Copy*
-- David Johnson CityRail Guard trainman@ozemail.com.au http://www.ozemail.com.au/~trainman/
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Message-ID: <35290EE3.FC733E3B@ozemail.com.au> Date: Tue, 07 Apr 1998 03:20:36 +1000 From: David Johnson <trainman@ozemail.com.au> Reply-To: trainman@ozemail.com.au X-Mailer: Mozilla 4.03 [en] (Win95; I) MIME-Version: 1.0 Newsgroups: aus.rail Subject: Re: Another City Rail Signalling Question References: <6gahhg$dt2$1@wbn.sydnet.com> <1998040616304900.MAA14610@ladder01.news.aol.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit
MarkBau1 wrote:
> Perhaps the speed proving in Sydney is different to the way speed proving works > in Melbourne and the UK. In Melbourne you might have 3 train stops between > signals. If the speed proving thinks you are going too fast to stop at the > signal the trip will stay up, they do not enforce speeds past an actual signal. > Thus, they trip at different speeds. >
Quoting from the Sydney Area re-signalling book:
"Low Speed Signals
"The low speed signal displays a small green light below two redsand authorises a train to proceed at a maximum speed of 27 km/h prepared to stop at the next signal.
"The low speed aspect operates on a reduced overlap and this provides for earlier clearing of signals when there is a train ahead, thus giving increased track capacity and flexibility when traffic becomes congested. The train stop associated with a signal displaying a low speed is not lowered until an approaching train has been timed to be travelling at a speed of 27 km/h or less in a manner similar to City Railway and E.S.R. working. A measure of safety is provided in that a train exceeding 27 km/h is tripped with a braking distance available from that signal to the next plus the low speed overlap beyond it. Having passed the low speed signal at 27 km/h, the overlap available past the next signal is sufficient for a train which trips at up to 27 km/h.
"Time clearing of train stops with the caution indication as occurs on the underground system is not provided."
End Quote.
The last paragraph refers to the fact that the caution indication is also set to trip trains going too fast, as the signals in the underground are very close together.
> Perhaps the drivers that didn't "get it" haven't worked with speed proving for > very long. Is it a new thing in Sydney? Melbourne has had speed proving for > quite a long time at various locations.
It has been in Sydney since at least September 23rd, 1979, which was the commissioning date of stage 1 of the Sydney area re-signalling, and possibly even as far back as 1926, when the underground first opened. Skillful drivers know what they are doing, and rarely, if ever, get tripped by a low speed signal.
-- David Johnson CityRail Guard trainman@ozemail.com.au http://www.ozemail.com.au/~trainman/
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