On Jun 25, 1:12 am, "John Rowland"
wrote:
Christopher A.Lee wrote:
On Sun, 24 Jun 2007 14:32:52 GMT, wrote:

My normal experience of Tube trains going through temporarily closed
stations is that they may slow to 5-10 miles, but they don't stop. I
guess that they are similar to draw up signals in that they will
clear if approached at a certain speed, assuming that there is no
train ahead of the one in the station.

I suspect the approach control signals are still there so they have to
slow for them.

It's actually to do with the lengths of the signal overlaps on the exit from
the station. A train departing a closed station at full speed can crash into
another train without being stopped by the signalling. A train departing the
station having stopped, or crawled, can't.



I guess that a lot of reasons coincide, and that slowing to a crawl
solves all of them. There must also be a risk of things falling on
the line if work is going on, and at a slow speed there would be a
better chance of stopping before a collision (or maybe swerving around
them, if LU trains have the same facilities as Pendolinos).

On Mon, 25 Jun 2007, MIG wrote:

On Jun 25, 1:12 am, "John Rowland"
wrote:
Christopher A.Lee wrote:
On Sun, 24 Jun 2007 14:32:52 GMT, wrote:

My normal experience of Tube trains going through temporarily closed
stations is that they may slow to 5-10 miles, but they don't stop.

There must also be a risk of things falling on the line if work is going
on, and at a slow speed there would be a better chance of stopping
before a collision

Putting up a hoarding between the platform and the track would surely be
an alternative, and better, way of doing this.

tom

--
sh(1) was the first MOO

In message . com, MIG
writes
On Jun 25, 1:12 am, "John Rowland"
wrote:
Christopher A.Lee wrote:
On Sun, 24 Jun 2007 14:32:52 GMT, wrote:

My normal experience of Tube trains going through temporarily closed
stations is that they may slow to 5-10 miles, but they don't stop. I
guess that they are similar to draw up signals in that they will
clear if approached at a certain speed, assuming that there is no
train ahead of the one in the station.

I suspect the approach control signals are still there so they have to
slow for them.

It's actually to do with the lengths of the signal overlaps on the exit from
the station. A train departing a closed station at full speed can crash into
another train without being stopped by the signalling. A train departing the
station having stopped, or crawled, can't.



I guess that a lot of reasons coincide, and that slowing to a crawl
solves all of them. There must also be a risk of things falling on
the line if work is going on, and at a slow speed there would be a
better chance of stopping before a collision (or maybe swerving around
them, if LU trains have the same facilities as Pendolinos).

Let's not guess then.

John was quite correct with the real reason. When a train runs out of
service (or non-stops a station) the rules state it must be travelling
at no more than 5 mph at the station starter - there is no rule about
the rest of the station platform.

This rule is in place solely because of the overlaps of the signalling
system. All LU signalling has been designed to assume that all trains
will stop at all stations; there are a few exceptions of course, such as
the fast lines Hammersmith to Acton Town on the Piccadilly. The
stopping distances for the overlaps have been calculated assuming this.
Therefore, a non-stopping train still has to be virtually stopped at the
station starter so that if a SPAD occurs, when the train is tripped it
will stop within the calculated stopping distance short of any train in
front.

This policy is now being enforced by starting signals that are held at
danger until a suitable time has elapsed from a timing point on the
track, they usually go to green just as the train stops. Not all
signals are fitted this way yet, but I understand that any upgraded
will include this feature.

There is nothing in the rules that says a train has to pass along the
platform at anything other than normal speed and, in fact, when I run
out of service, I do a normal stop into the platform and release the
brakes and start motoring again as I hit about 7-8 mph (the brakes are
slightly delayed releasing, so I am actually doing 5 mph before I start
motoring again).
--
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)

On Jun 25, 1:26 pm, Steve Fitzgerald ] wrote:
In message . com, MIG
writes





On Jun 25, 1:12 am, "John Rowland"
wrote:
Christopher A.Lee wrote:
On Sun, 24 Jun 2007 14:32:52 GMT, wrote:

My normal experience of Tube trains going through temporarily closed
stations is that they may slow to 5-10 miles, but they don't stop. I
guess that they are similar to draw up signals in that they will
clear if approached at a certain speed, assuming that there is no
train ahead of the one in the station.

I suspect the approach control signals are still there so they have to
slow for them.

It's actually to do with the lengths of the signal overlaps on the exit from
the station. A train departing a closed station at full speed can crash into
another train without being stopped by the signalling. A train departing the
station having stopped, or crawled, can't.

I guess that a lot of reasons coincide, and that slowing to a crawl
solves all of them. There must also be a risk of things falling on
the line if work is going on, and at a slow speed there would be a
better chance of stopping before a collision (or maybe swerving around
them, if LU trains have the same facilities as Pendolinos).

Let's not guess then.


Well that's told me.

Still, what you are saying is that there is a rule which always
applies, and for which there is the reason that you have given, such
that any other reasons for slowing don't require any additional rules.

That doesn't mean that there couldn't be any other reasons, just that
there may not need to be any other rules.



John was quite correct with the real reason. When a train runs out of
service (or non-stops a station) the rules state it must be travelling
at no more than 5 mph at the station starter - there is no rule about
the rest of the station platform.

This rule is in place solely because of the overlaps of the signalling
system. All LU signalling has been designed to assume that all trains
will stop at all stations; there are a few exceptions of course, such as
the fast lines Hammersmith to Acton Town on the Piccadilly. The
stopping distances for the overlaps have been calculated assuming this.
Therefore, a non-stopping train still has to be virtually stopped at the
station starter so that if a SPAD occurs, when the train is tripped it
will stop within the calculated stopping distance short of any train in
front.

This policy is now being enforced by starting signals that are held at
danger until a suitable time has elapsed from a timing point on the
track, they usually go to green just as the train stops. Not all
signals are fitted this way yet, but I understand that any upgraded
will include this feature.

There is nothing in the rules that says a train has to pass along the
platform at anything other than normal speed and, in fact, when I run
out of service, I do a normal stop into the platform and release the
brakes and start motoring again as I hit about 7-8 mph (the brakes are
slightly delayed releasing, so I am actually doing 5 mph before I start
motoring again).
--
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)- Hide quoted text -

- Show quoted text -

I think that a stipulated restricted speed when passing stations is standard
procedure on many undergrounds throughout the world for a number of reasons.

"Steve Fitzgerald" ] wrote in message
... .

John was quite correct with the real reason. When a train runs out of
service (or non-stops a station) the rules state it must be travelling at
no more than 5 mph at the station starter - there is no rule about the
rest of the station platform.

Still on-topic (although not for this thread!) but a nice way to end
the week and topic

The London Underground Song
http://www.fridaytowers.com/fitness/gig.php

A bit sweary, so not for kids.