Wimbledon branch of District line - why us?
 

Whenever there is a signal failure, etc. anywhere on the District line it
always seems to affect the Wimbledon branch more than any other.

Today there were several Ealing Broadway trains and an Olympia train from
Earls Court (all nearly empty) while a platform full of people waited for a
Wimbledon train. When it eventually did arrive it was there for a while
because it was "over an hour late" and the driver had to have a "frank
discussion on the platform" over whether it was going to Wimbledon. It's a
good thing it did because despite being 2015 it was as full as the morning
peak services into the city are and lots of passngers sounded annoyed

My questions a
1. Why did the only audiable announcment say "because of an earlier
incident" instead of a reason and why did the LU chap on the platform with
the white wand not do any announcments?
2. Why couldn't the empty Ealing Broadway train which was immediately
behind another Ealing bdy train have been made into a Wimbledon one?
3. Why were there no C stock trains around in either direction
4. Why is it always the Wimbledon branch that is most affected?
and finally 4. When will the tubes ETA service be expanded to the District
line

I thought that since a lot of drivers post here it's better to ask this way
than via customer services who "can only appologise" and hope "with the
onset of PPP" everything will be sorted out

--
Chris

Wimbledon branch of District line - why us?
 

Chris wrote:
My questions a
1. Why did the only audiable announcment say "because of an earlier
incident" instead of a reason and why did the LU chap on the platform
with
the white wand not do any announcments?

You have my sympathies, Chris. Today was a complete cock-up for the
entire District Line, and you're right, the Wimbledon branch always
seems to suffer more than Ealing or Richmond!
To try and answer your questions, the announcements at Earl's Court are
now generally made using the pre-recorded voice system they've just had
installed. Not sure why it was saying an 'incident' rather than
'signal failure/emergency engineering work', I have no idea.
As for the SA with the baton, I can't answer for him!

2. Why couldn't the empty Ealing Broadway train which was
immediately
behind another Ealing bdy train have been made into a Wimbledon one?

If there was a train running empty, it would have been defective in
some way, and on its way to the depot at Ealing Common. I've never
known a train be permitted to run empty just because of late running
etc.

3. Why were there no C stock trains around in either direction

The C stocks were around, but because of the delays through the City,
everything was being queued up waiting to get into Earl's Court because
of train crews being in the wrong places etc. I would guess that the C
stocks must have been stuck up towards Edgware Road.

4. Why is it always the Wimbledon branch that is most affected?

Usually when there's a problem, the Wimbledon branch still gets a
reasonable service. The main problem with that branch is the large
amount of failures which actually occur on it! The section between
East Putney and Wimbledon is signalled and controlled by Network Rail,
and there is a long standing problem down there with signals 'bobbing'
with the slightest shower of rain! Hopefully this will be addressed
before too long.

and finally 4. When will the tubes ETA service be expanded to the
District
line

That's the million pound question! I wouldn't hold your breath...

I thought that since a lot of drivers post here it's better to ask
this way
than via customer services who "can only appologise" and hope "with
the
onset of PPP" everything will be sorted out

Good old Customer Services! All I can say is that we drivers can't
control where we go! If the Line Controller tells us to divert to
Ealing or Richmond, there's nothing we can do about it! The controller
should be monitoring each of the branches to make sure that there's a
fair service to each. It really depends on which controller is working
at the time, and whether he's been given orders from the Duty
Operations Manager.
Ealing Broadway also suffered a bit, as I noticed 4 consecutive
Richmond services passing through Earl's Court at around 2100ish.

Hopefully that's answered your questions. I know it's frustrating (LU
staff have to use the District Line to commute as well!) but until we
get a huge investment in the line and replace the old 'technology' with
something a bit more reliable, these delays will, sadly, continue.

Wimbledon branch of District line - why us?
 

DistrictDriver wrote:
Chris wrote:
The section between
East Putney and Wimbledon is signalled and controlled by Network
Rail,
and there is a long standing problem down there with signals
'bobbing'
with the slightest shower of rain! Hopefully this will be addressed
before too long.

Can you explain what bobbing is.

Kevin

Wimbledon branch of District line - why us?
 

Wimbledon branch of District line - why us?
 

Bobbing is where the signal changes from red to green and back again or vice
versa. Its caused by something causing the track circuit to be made, like
water lying on the track, imitating a train. So signalers dont know whats in
the area, the train stops raise up and everything stops. Then once its been
found the area is empty and its a fault, drivers can go past the signal but
at reduced speeds etc....a little more detail but i wont bore you. This
causes a backlog and the cycle of delay starts.......


wrote in message
oups.com...

DistrictDriver wrote:
Chris wrote:
The section between
East Putney and Wimbledon is signalled and controlled by Network
Rail,
and there is a long standing problem down there with signals
'bobbing'
with the slightest shower of rain! Hopefully this will be addressed
before too long.

Can you explain what bobbing is.

Kevin

Wimbledon branch of District line - why us?
 

"TheOneKEA" wrote in message
ps.com...

"Bobbing" is when the signal rapidly changes
from aspect to aspect without warning or reason.

Naturally this is a major problem because a signal
could bob despite an occupied track in front of the
train; thus, if it goes to green and the driver passes
it in the correct way at speed, CRUNCH.

I doubt that, because it would violate the concept of "failsafe".

--
John Rowland - Spamtrapped
Transport Plans for the London Area, updated 2001
http://www.geocities.com/Athens/Acro...69/tpftla.html
A man's vehicle is a symbol of his manhood.
That's why my vehicle's the Piccadilly Line -
It's the size of a county and it comes every two and a half minutes

Wimbledon branch of District line - why us?
 

John Rowland wrote:
"TheOneKEA" wrote in message
ps.com...

"Bobbing" is when the signal rapidly changes
from aspect to aspect without warning or reason.

Naturally this is a major problem because a signal
could bob despite an occupied track in front of the
train; thus, if it goes to green and the driver passes
it in the correct way at speed, CRUNCH.

I doubt that, because it would violate the concept of "failsafe".


Maybe, maybe not. If the signals are bobbing at all then you have a
problem; under the right circumstances, a soaking wet relay cabinet
would probably produce a wrong-side failure. Knowing very little about
signal design I can't say how likely it is to happen.

Wimbledon branch of District line - why us?
 

"Bobbing" is when the signal rapidly changes from aspect to aspect
without warning or reason. ...

Over here they call that "cascading".
--
Mark Brader "He added a 3-point lead" is pronounced
Toronto differently in Snooker than in Typography...
-- Liam Quin

Wimbledon branch of District line - why us?
 

I doubt that, because it would violate the concept of "failsafe".

Even failsafe systems have a small but finite chance of not failing
safe (ask Airbus!).
However I'm not an electrical/electronics engineer so I could be
talking ******** but I'd
imagine if you've got some seriously old and knackered equipment along
with some
dodgy weather then shorts could occur , critical components in the
failsafe system
could fail etc.

Any engineers reading this who could clarify?

B2003

Wimbledon branch of District line - why us?
 

Boltar wrote:
I doubt that, because it would violate the concept of "failsafe".

Even failsafe systems have a small but finite chance of not failing
safe (ask Airbus!).
However I'm not an electrical/electronics engineer so I could be
talking ******** but I'd
imagine if you've got some seriously old and knackered equipment along
with some
dodgy weather then shorts could occur , critical components in the
failsafe system
could fail etc.

Any engineers reading this who could clarify?


I'm not an engineer, but it has been known for externalities to enter the
system and cause a foul up.

Wimbledon branch of District line - why us?
 

and finally 4. When will the tubes ETA service be expanded to the
District
line

i'd love to see it on the northern line:)

Wimbledon branch of District line - why us?
 

In article om,
TheOneKEA writes
"Bobbing" is when the signal rapidly changes from aspect to aspect
without warning or reason.

You mean "or apparent reason".

By far the commonest reason for bobbing is that one of the controlling
track circuits is being intermittently shorted out or failing open
circuit. For example, if one of the wires bonding adjacent rails is
loose, the circuit can break and re-make under the vibration of trains
on adjacent tracks.

Naturally this is a major problem because a signal could bob despite an
occupied track in front of the train; thus, if it goes to green and the
driver passes it in the correct way at speed, CRUNCH.

Bobbing *to* green is extremely unlikely, because it requires a false
feed at an appropriate point (and circuits are usually designed to
require two false feeds for a wrong-side failure). There's no obvious
situation, comparable to the one above, to cause this.

--
Clive D.W. Feather | Home:
Tel: +44 20 8495 6138 (work) | Web: http://www.davros.org
Fax: +44 870 051 9937 | Work:
Please reply to the Reply-To address, which is:

Wimbledon branch of District line - why us?
 

"Chris" wrote in message
. ..

I have now had a reply from customer services....


snip

My questions a
1. Why did the only audiable announcment say "because of an earlier
incident" instead of a reason and why did the LU chap on the platform with
the white wand not do any announcments?

Apparently it is now the tubes policy to provide the shortest announcment
possible. Don't know why, we were standing there long enough to hear a more
precise announcment


2. Why couldn't the empty Ealing Broadway train which was immediately
behind another Ealing bdy train have been made into a Wimbledon one?

She completely missed my point and said sometimes trains are swapped around
and this is done to the best of the signalers ability, If that was the case
there wouldn't have been Ealing Bdy trains with 6 or so people per carriage
and then eventually a Wimbledon train with commuter style two rows of people
between the seats, body parts touching, not all fitting on.


3. Why were there no C stock trains around in either direction

She said there were. Wonder were they were - we didn't pass any after
leaving Earls Ct. There were long gaps of time when they could have come
into platform 4 aswell. Could they have all been queueing for Edgware Road?

4. Why is it always the Wimbledon branch that is most affected?
and finally 4. When will the tubes ETA service be expanded to the
District line


Apparently the whole line is always affected as badly - hmm in that case I
must have imagined the overcrowding

Wimbledon branch of District line - why us?
 

Clive D. W. Feather wrote:

You mean "or apparent reason".

Indeed.


By far the commonest reason for bobbing is that one of the
controlling track circuits is being intermittently shorted out
or failing open circuit. For example, if one of the wires
bonding adjacent rails is loose, the circuit can break and
re-make under the vibration of trains on adjacent tracks.


True. District Dave once described a track circuit failure involving
a broken wire; he was involved in its repair.


Bobbing *to* green is extremely unlikely, because it requires
a false feed at an appropriate point (and circuits are usually
designed to require two false feeds for a wrong-side failure).
There's no obvious situation, comparable to the one above, to
cause this.

I don't know much about the trackside arrangements for track circuits,
so I accept what you've said.

Is it possible for a wet track circuit to short out in such a way that
a green aspect could be obtained? You've stated that track circuits
require a pair of false feeds to turn green; in the case of East Putney
- Wimbledon, what would need to get wet to cause such a wrong-side
failure?

Wimbledon branch of District line - why us?
 

In article . com,
TheOneKEA writes
Is it possible for a wet track circuit to short out in such a way that
a green aspect could be obtained?

Extremely difficult.

The basic design of a track circuit is very simple:

Supply Relay
| | | |
| | | |
=:=+==========+= =+===========+= =+==========+= =+=======+==:==
| \---/ \---/ \---/ |
/--/ \-\
| /---\ /---\ /---\ |
=:=+==========+= =+===========+= =+==========+= =+=======+==:==

=== running rail
=:= insulated gap
= = ordinary gap between rails
=+= wire bonded to rail
|

The supply will be DC in some areas, but AC at a specific frequency on
LU. The relay will be tuned to the same frequency (so a feed from an
adjacent track circuit won't trigger it). The wheels and axles of the
train short the rails, causing the relay to de-energise. Any fault in
the wiring causes the relay to de-energise. But to get a false clear on
the relay you've got to feed significant amounts of 83 1/3 Hz (or
whatever) current into the circuit to the right of the location of the
train.

You've stated that track circuits
require a pair of false feeds to turn green;

More that "double fault" is a general principle. In-the-field circuits
are often double cut (that is, both supply and return are switched by
the controlling relay) so that a false feed or false earth doesn't
trigger it.

in the case of East Putney
- Wimbledon, what would need to get wet to cause such a wrong-side
failure?

I'd be surprised if simply having water in the wrong place would
suffice. A wiring fault would be much more likely.

Are you talking about a specific event, or just a general enquiry?

--
Clive D.W. Feather | Home:
Tel: +44 20 8495 6138 (work) | Web: http://www.davros.org
Fax: +44 870 051 9937 | Work:
Please reply to the Reply-To address, which is:

Wimbledon branch of District line - why us?
 

In article , Clive D. W. Feather
wrote:
In article . com,
TheOneKEA writes
Is it possible for a wet track circuit to short out in such a way that
a green aspect could be obtained?

Extremely difficult.

The basic design of a track circuit is very simple:

Supply Relay
| | | |
| | | |
=:=+==========+= =+===========+= =+==========+= =+=======+==:==
| \---/ \---/ \---/ |
/--/ \-\
| /---\ /---\ /---\ |
=:=+==========+= =+===========+= =+==========+= =+=======+==:==

=== running rail
=:= insulated gap
= = ordinary gap between rails
=+= wire bonded to rail
|

The supply will be DC in some areas, but AC at a specific frequency on
LU. The relay will be tuned to the same frequency (so a feed from an
adjacent track circuit won't trigger it). The wheels and axles of the
train short the rails, causing the relay to de-energise. Any fault in
the wiring causes the relay to de-energise. But to get a false clear on
the relay you've got to feed significant amounts of 83 1/3 Hz (or
whatever) current into the circuit to the right of the location of the
train.


It is my understanding that 83 Hz is more complex and harder to beat than
this.

We have all seen induction motors. Sometimes they are 3 phase, but sometimes
they are single phase. A phase at right angles to the main supply is created
by passing the current through a capacitor and the rotor is rotated by
currents induced by the two magnetic fields. In railway practice, a relay
vane is lifted by the two fields, which MUST be at right angles to each
other. So, the 83 current is detected, not only because it is at the right
frequency, but ALSO because it is at right angles ("in quadrature") to a
pilot current supplied from the 83 generator. It is very difficult for a
false positive to be given.

Michael Bell
--

Wimbledon branch of District line - why us?
 

Clive D. W. Feather wrote:

Extremely difficult.

The basic design of a track circuit is very simple:

Supply Relay
| | | |
| | | |
=:=+==========+= =+===========+= =+==========+= =+=======+==:==
| \---/ \---/ \---/ |
/--/ \-\
| /---\ /---\ /---\ |
=:=+==========+= =+===========+= =+==========+= =+=======+==:==

=== running rail
=:= insulated gap
= = ordinary gap between rails
=+= wire bonded to rail
|

The supply will be DC in some areas, but AC at a specific frequency
on LU. The relay will be tuned to the same frequency (so a feed from
an adjacent track circuit won't trigger it).
The wheels and axles of the train short the rails, causing the
relay to de-energise. Any fault in the wiring causes the relay to
de-energise. But to get a false clear on the relay you've got to
feed significant amounts of 83 1/3 Hz (or whatever) current into
the circuit to the right of the location of the train.

Ah, I see. I'd never actually seen a proper diagram of a track circuit
before; this makes things nice and clear.


More that "double fault" is a general principle. In-the-field
circuits are often double cut (that is, both supply and return are
switched by the controlling relay) so that a false feed or false
earth doesn't trigger it.

OK.


Are you talking about a specific event, or just a general enquiry?


I'm making a general inquiry. Most of the stuff I've read from District
Line drivers states that the slightest wet down there causes massive
problems with the signalling. I was just curious as to whether or not
those problems could cause a wrong-side failure.

Wimbledon branch of District line - why us?
 

In article .com,
TheOneKEA writes
I'm making a general inquiry. Most of the stuff I've read from District
Line drivers states that the slightest wet down there causes massive
problems with the signalling.

This doesn't surprise me.

There's always a certain amount of current leaking between the rails
through the ballast; in effect you have to treat the circuit as having a
resistor there rather than a gap. The resistance varies *a lot* between
wet and dry conditions, and tuning the parameters of the circuit so that
this leakage doesn't look like a train is a bit of a fine art. If it's
got slightly wrong, the TC will drop out, looking to the rest of the
system like a train where no train should be. Hence problems.

The different electrical arrangements south of Putney, and the need to
interface with NR signalling, doesn't help either.

I was just curious as to whether or not
those problems could cause a wrong-side failure.

This would surprise me.

--
Clive D.W. Feather | Home:
Tel: +44 20 8495 6138 (work) | Web: http://www.davros.org
Fax: +44 870 051 9937 | Work:
Please reply to the Reply-To address, which is:

Wimbledon branch of District line - why us?
 

If you have a train out of service going through Earls Court to Ealing
Common, it gets described as Ealing Broadway, that's how crap the
description system is.

Wanderingjew698 wrote:
and finally 4. When will the tubes ETA service be expanded to the

District

line


i'd love to see it on the northern line:)