In message ,
writes

I tentatively think this focus on the lack of signals is a bit
misleading. Ultimately, all safety on non-ATO lines depends on
drivers correctly responding to signals (barring tripcocks - am i
right i thinking these are only present at a fraction of signals?).
If we accept that stopping at a red is an acceptable part of the
safety mechanism, why can't we also accept that stopping at the
absence of a green, or the absence of any signal, is?

Tripcocks are present at all home signals on LUL lines.

You meant to say:

Tripcocks are present at all stop signals on LUL lines.

Didn't you?
--
Steve Fitzgerald has now left the building.
You will find him in London's Docklands, E16, UK
(please use the reply to address for email)

In article , ] (Steve
Fitzgerald) wrote:

In message ,
writes

I tentatively think this focus on the lack of signals is a bit
misleading. Ultimately, all safety on non-ATO lines depends on
drivers correctly responding to signals (barring tripcocks - am i
right i thinking these are only present at a fraction of signals?).
If we accept that stopping at a red is an acceptable part of the
safety mechanism, why can't we also accept that stopping at the
absence of a green, or the absence of any signal, is?

Tripcocks are present at all home signals on LUL lines.

You meant to say:

Tripcocks are present at all stop signals on LUL lines.

Didn't you?

Yes. I wondered whether I'd got it wrong when I wrote it. I meant to
exclude distant signals.

--
Colin Rosenstiel

In message ,
writes

Tripcocks are present at all home signals on LUL lines.

You meant to say:

Tripcocks are present at all stop signals on LUL lines.

Didn't you?

Yes. I wondered whether I'd got it wrong when I wrote it. I meant to
exclude distant signals.

We don't have a concept of distant signals on LUL, only stop signals and
repeaters where sighting is restricted.

There are of course station starters (as far as I know at every station
but I'm sure someone will come along and tell me otherwise) and approach
signals to stations (known as outer, intermediate and inner home
signals). Long sections between stations are also split up into
sections with running signals (usually automatic). The key point is
that they are all stop signals (ie can show a red aspect) and as such
have an associated train stop. A repeater only being able to show a
green or yellow aspect does not have a train stop.

I think the point that has been made in this discussion (I've avoided
comments due to where I work) is that the train in question was routed
where it shouldn't have been but with normal signals exiting the sidings
and as such the driver would then have no signals to observe (and thus
no associated train stop to trip the train). I can't disagree with the
observation that the driver's route knowledge should have told them that
something was not right and I believe from the initial RAIB report this
is what happened and the driver realised and stopped the train.

I look forward to seeing the full report if the RAIB to find out what
lessons can be learned for future safety.
--
Steve Fitzgerald has now left the building.
You will find him in London's Docklands, E16, UK
(please use the reply to address for email)

In article , ] (Steve
Fitzgerald) wrote:

In message ,
writes

Tripcocks are present at all home signals on LUL lines.

You meant to say:

Tripcocks are present at all stop signals on LUL lines.

Didn't you?

Yes. I wondered whether I'd got it wrong when I wrote it. I meant to
exclude distant signals.

We don't have a concept of distant signals on LUL, only stop
signals and repeaters where sighting is restricted.

There are of course station starters (as far as I know at every
station but I'm sure someone will come along and tell me otherwise)
and approach signals to stations (known as outer, intermediate and
inner home signals). Long sections between stations are also split
up into sections with running signals (usually automatic). The key
point is that they are all stop signals (ie can show a red aspect)
and as such have an associated train stop. A repeater only being
able to show a green or yellow aspect does not have a train stop.

I think the point that has been made in this discussion (I've
avoided comments due to where I work) is that the train in question
was routed where it shouldn't have been but with normal signals
exiting the sidings and as such the driver would then have no
signals to observe (and thus no associated train stop to trip the
train). I can't disagree with the observation that the driver's
route knowledge should have told them that something was not right
and I believe from the initial RAIB report this is what happened
and the driver realised and stopped the train.

I look forward to seeing the full report if the RAIB to find out
what lessons can be learned for future safety.

Thanks for correcting my terminology, Steve. I was exactly meaning to
exclude repeaters which don't have train stops. Does that include fog
repeaters, BTW?

What seems to be rare on LU is three aspect signals. There used to be one
at the entrance to the Southbound platform at East Putney but that might
be BR practice.

--
Colin Rosenstiel

In message ,
writes

I look forward to seeing the full report if the RAIB to find out
what lessons can be learned for future safety.

Thanks for correcting my terminology, Steve. I was exactly meaning to
exclude repeaters which don't have train stops. Does that include fog
repeaters, BTW?

Yes it does. There are no fog repeaters with red aspects (after all,
they wouldn't be a repeater then would they?)

What seems to be rare on LU is three aspect signals. There used to be one
at the entrance to the Southbound platform at East Putney but that might
be BR practice.

On LU They are generally speed controlled signals and work in a subtly
different way although they are still stop signals and have a train
stop.

If they show green, there is a clear route set and no speed checking is
in place.

If they show red, speed checking is in place and the signal will show a
yellow aspect and the train stop will drop when the train's speed has
been proved below a set figure.

They are mainly used to protect reduced overlaps on signals to ensure a
train doesn't go thundering through an area with the potential risk of
collision.

All speed control signals seem to work in slightly different ways
depending on the local requirements and road learning includes these
nuances.

Of course where we share with BR then their signalling practices are in
force.
--
Steve Fitzgerald has now left the building.
You will find him in London's Docklands, E16, UK
(please use the reply to address for email)

In article , ] (Steve
Fitzgerald) wrote:

In message ,
writes

What seems to be rare on LU is three aspect signals. There used to be
one at the entrance to the Southbound platform at East Putney but that
might be BR practice.

On LU They are generally speed controlled signals and work in a
subtly different way although they are still stop signals and have
a train stop.

If they show green, there is a clear route set and no speed
checking is in place.

If they show red, speed checking is in place and the signal will
show a yellow aspect and the train stop will drop when the train's
speed has been proved below a set figure.

They are mainly used to protect reduced overlaps on signals to
ensure a train doesn't go thundering through an area with the
potential risk of collision.

LU rules could have applied at East Putney then, with the speed control
for the approach to the junction at the platform ends.

All speed control signals seem to work in slightly different ways
depending on the local requirements and road learning includes
these nuances.

Of course where we share with BR then their signalling practices
are in force.

The example at East Putney was on non-shared track but I think has been
removed. It may have dated from the days when some trains non-stopped East
Putney.

--
Colin Rosenstiel

[Yes, I only just saw this thread.]

In message , Steve Fitzgerald
] wrote:
What seems to be rare on LU is three aspect signals. There used to be one
at the entrance to the Southbound platform at East Putney but that might
be BR practice.

On LU They are generally speed controlled signals and work in a subtly
different way although they are still stop signals and have a train
stop.

If they show green, there is a clear route set and no speed checking is
in place.

If they show red, speed checking is in place and the signal will show a
yellow aspect and the train stop will drop when the train's speed has
been proved below a set figure.

I'm not sure if any still do, but they used to show red+yellow (with
train stop up) to show the train had entered the timing track circuit,
then change to plain yellow (with train stop down) after sufficient time
to ensure the train had slowed enough (if it hadn't, it would be tripped
before the signal could change).

Of course where we share with BR then their signalling practices are in
force.

Only when it's their track.

There *are* true LU three- and four-aspect signals on the Metropolitan
Line north of Harrow-on-the-Hill.

--
Clive D.W. Feather | Home:
Mobile: +44 7973 377646 | Web: http://www.davros.org
Please reply to the Reply-To address, which is:

On 29/09/2010 06:58, Clive D. W. Feather wrote:
[Yes, I only just saw this thread.]

In message , Steve Fitzgerald
] wrote:
What seems to be rare on LU is three aspect signals. There used to be
one
at the entrance to the Southbound platform at East Putney but that might
be BR practice.

On LU They are generally speed controlled signals and work in a subtly
different way although they are still stop signals and have a train stop.

If they show green, there is a clear route set and no speed checking
is in place.

If they show red, speed checking is in place and the signal will show
a yellow aspect and the train stop will drop when the train's speed
has been proved below a set figure.

I'm not sure if any still do, but they used to show red+yellow (with
train stop up) to show the train had entered the timing track circuit,
then change to plain yellow (with train stop down) after sufficient time
to ensure the train had slowed enough (if it hadn't, it would be tripped
before the signal could change).

Of course where we share with BR then their signalling practices are
in force.

Only when it's their track.

Where do tube or sub-surface trains run that is strictly NR territory?



There *are* true LU three- and four-aspect signals on the Metropolitan
Line north of Harrow-on-the-Hill.

I thought those would be NR signals. I notice that they still have the
separate stop arms for LU stock and AWS for NR stock.

"Steve Fitzgerald" ] wrote in message
...
In message ,
writes

There are of course station starters (as far as I know at every station
but I'm sure someone will come along and tell me otherwise)

Croxley...
--
Cheers, Steve.
Change jealous to sad to reply.

On Sat, 11 Sep 2010, Steve Fitzgerald wrote:

In message ,
writes

I tentatively think this focus on the lack of signals is a bit
misleading. Ultimately, all safety on non-ATO lines depends on drivers
correctly responding to signals (barring tripcocks - am i right i
thinking these are only present at a fraction of signals?). If we
accept that stopping at a red is an acceptable part of the safety
mechanism, why can't we also accept that stopping at the absence of a
green, or the absence of any signal, is?

Tripcocks are present at all home signals on LUL lines.

You meant to say:

Tripcocks are present at all stop signals on LUL lines.

Didn't you?

Naturally.

Does 'stop signal' mean 'signal capable of telling a train to stop', ie
anything that can go red, as opposed to route indicators etc? If so, i
hadn't realised that, i stand educated, that's a very good thing, and i'm
surprised there wasn't something along those lines protecting the
wrong-way move that was possible here, some sort of always-on tripcock
alongside the board saying YOU ARE GOING THE WRONG WAY.

tom

--
Give the future a chance!