Re: New questions for rail experts

[signal_spotter@my-deja.com]

In article <392a7311$0$2628@news01.syd.optusnet.com.au>,
  "Greg Cantori" <greg@mpx.com.au> wrote:
> 1. On each platform there is a blue light called the "guards
indicator".
>    What is its purpose, and why does it turn on and off?
>
> 2. On the tracks every 50 metres or so is a metal switch-thing that
>    is up after a train has passed, then flips down when the train is
>    a safe distance ahead. Presuming this causes a following train to
>    brake if it goes over it while up, why doesn't the train that
>    set it up in the first place get caught when its last carraiges
>    go over it? (unless of course it's the last carriage that sets it
up!)
>
> 3. Why don't guards shut up and let passengers relax/sleep? Do we
>    really need to be constantly told where the train that we
deliberately
>    caught is going?  Inter-urban services are usually quite
considerate
>    in this respect, but city trips can be a barrage of repititious
>    chatter, and is totally unneccesary.
>
> 4. What's a "V" set that people on this list always talk about?
>    (Another name for a Tangara, taken from the shape of the 4th and
5th
>     carriages in a set of 8 cars?)
>
> --
>
> Greg Cantori   greg@mpx.com.au  and  gcantori@hcf.com.au
> The Griper
> http://www.mtgparadise.com/articles/columns/griper.shtml
> Poker, Magic, Astronomy, Journalism, Science, Truth
>

OK to answer everyones queries about trainstops, catch points I'll
explain it in technical detail. Guards Indicators have been pretty well
explained by the others so I won't elaborate.

Trainstops. The arm that you see raise and lower is a trainstop. When
the signal is at red it is raised. When the aspect is cleared ie
yellow, green etc it lowers straight away. Normally subsidiary shunts
don't drive the trainstops unless it's a specific passenger move under
a shunt signal. Not that normal but there are a few cases say at
Hornsby. Also if the signal is capable of showing a low speed aspect
then the lowering of the trainstop is acheived after proving the
approach speed of the train at 35kph. They are positioned at all
mainline signals (not ground shunts) to stop a train (ones fitted with
trip cocks) if it passes the signal at stop. There is also a
requirement for Intermediate Trainstops if there is little or no
overlap (the margin of error worked out using trip braking curves based
on the linespeed) after the next signal. These are what you may be
referring to every 50 m or so. They are positioned to prove the train
at 35kph, then 25kph and then 10kph. The latter 2 required if the
overlap is <100m. To answer another postee's gripe about catchpoints,
we are currently putting in Intermediate Trainstops throughout Sydney
on routes leading up to catchpoints. I personally have designed
Coalcliff, Scarborough, Dapto (that's not a CP but for another reason)
and a few others. Anyway what we hope to acheive is that for signals
reading up to open catchpoints the signal in the rear will display a
low speed (with a timed approach) and when the train has been proven at
35kph it's then tracked through the route (at 25kph and 10kph) dropping
the ITS's as he goes. What that means is that by the time he reaches
the end signal (that's at stop) and with an open catch his speed will
have been proven that if he does trip past it, it will be at a low
enough speed (10 kph) that he will not progress through and derail. If
his speed exceeds then he will trip on an ITS prior to the stop signal.

Anyway hope this explains trainstops.

regards Ian Hayes
Signal Design Engineer


>


Sent via Deja.com http://www.deja.com/
Before you buy.