On Fri, 17 Mar 2006, Clive D. W. Feather wrote:

In article , Tom Anderson
writes

What might be sensible would be if preparatory work for the change was
done now - for instance, stringing catenary to Shepherd's Bush, but not
wiring it up to the mains.

Do you think it would still be there in 6 years time?

I have to admit that it had never occurred to me that people might steal
it. Okay, scratch that - but could there be other bits of work that could
be done cheaply now?

With any luck, the changeover could then be done just by setting some
jumpers in a cable cabinet somewhere, rather than having to get the
permanent way gang out again.

I would hope it would be deliberately made a lot harder than that. Do
you really want an accident waiting to happen?

You mean like maybe sticking some masking tape over it? Seems a bit
paranoid, but if you insist.

And I do not understand what the hell resignalling of the Hammersmith
and City Line has to do with this at all!

This, i have to admit, is a puzzle - how the hell is the H&C wired to
the WLL?

It isn't, but there are such things as earth leakage and induction.

Righto. I hadn't realised these things were powerful enough that you could
get coupling between two lines which simply cross one another on different
levels at one point.

I know someone involved in the electrification work on CTRL2. He has to
worry about the fact that the Underground tube tunnels, the King's Cross
station structure, the St.Pancras station structure, and the NLL all
have different values for "earth". He reckons that if he gets things
wrong, opening a breaker at Ashford could cause a lethal change in earth
voltage at the KXSP complex.

Eek.

tom

--
Why do we do it? - Exactly!

Clive D. W. Feather wrote:

Tom Anderson writes
What might be sensible would be if preparatory work for the change was
done now - for instance, stringing catenary to Shepherd's Bush, but not
wiring it up to the mains.

Do you think it would still be there in 6 years time?

Would the people who would otherwise steal it know whether it was
switched off?

With any luck, the changeover could then be done just by setting some
jumpers in a cable cabinet somewhere, rather than having to get the
permanent way gang out again.

I would hope it would be deliberately made a lot harder than that. Do
you really want an accident waiting to happen?

That depends what "an accident waiting to happen" means. How much money
is it worth spending to avoid the combination of two very unlikely
events?

And I do not understand what the hell resignalling of the Hammersmith
and City Line has to do with this at all!
This, i have to admit, is a puzzle - how the hell is the H&C wired to
the WLL?

It isn't, but there are such things as earth leakage and induction.

I know someone involved in the electrification work on CTRL2. He has to
worry about the fact that the Underground tube tunnels, the King's Cross
station structure, the St.Pancras station structure, and the NLL all
have different values for "earth". He reckons that if he gets things
wrong, opening a breaker at Ashford could cause a lethal change in earth
voltage at the KXSP complex.

Why would a change in earth voltage be lethal?

If extending the wires is such a problem, why don't they just extend the
third rail instead? The local passenger trains would no longer need to
be dual voltage, and would therefore be cheaper. The longer distance
electric trains may still have to stop, but as they could do so while
the local trains are in the station, pathing would no longer be such a
problem!

--
Aidan Stanger
http://www.bettercrossrail.co.uk

In article , Aidan Stanger
writes
Do you think it would still be there in 6 years time?
Would the people who would otherwise steal it know whether it was
switched off?

They tend to find out.

With any luck, the changeover could then be done just by setting some
jumpers in a cable cabinet somewhere, rather than having to get the
permanent way gang out again.
I would hope it would be deliberately made a lot harder than that. Do
you really want an accident waiting to happen?
That depends what "an accident waiting to happen" means. How much money
is it worth spending to avoid the combination of two very unlikely
events?

I'd want it to require two separate highly non-trivial actions in
different places (e.g. installing several metres of cable) to energise.
This shouldn't require spending extra money. And, in any case, you'd
need to get the gang out to check all was okay before energising - how
would you know a wire hasn't come lose and is touching another?

I know someone involved in the electrification work on CTRL2. He has to
worry about the fact that the Underground tube tunnels, the King's Cross
station structure, the St.Pancras station structure, and the NLL all
have different values for "earth". He reckons that if he gets things
wrong, opening a breaker at Ashford could cause a lethal change in earth
voltage at the KXSP complex.
Why would a change in earth voltage be lethal?

Because when one "earth" is 90V from another "earth", anyone bridging
the two is going to get a nasty shock.

25000 V AC and 5000 A in complex combinations is hard to get right.

If extending the wires is such a problem, why don't they just extend the
third rail instead?

Because it's even more expensive - you need substations every few km and
there are severe limits on power.

--
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:

On Sun, 26 Mar 2006 00:01:44 +1030, (Aidan Stanger)
wrote:

Clive D. W. Feather wrote:

Tom Anderson writes
What might be sensible would be if preparatory work for the change was
done now - for instance, stringing catenary to Shepherd's Bush, but not
wiring it up to the mains.

Do you think it would still be there in 6 years time?

Would the people who would otherwise steal it know whether it was
switched off?


When I lived in Newcastle (admittedly 15 years ago) it was a fairly
standard occurence that the Metro line would be closed for a few days
on one of the sections around Longbenton, Wallsend, or Pelaw, because
someone had hooked a landrover to the signal cabling in the troughs or
the catenary and pulled massive lengths of it out/down in order to
steal it for scrap.

I don't live there any more so don't know if it still goes on.

On Fri, 17 Mar 2006 13:44:19 +0000, Paul Terry
wrote:

In message , Dave Arquati
writes

I should make clear that it's not a *huge* drop - about three metres I
guess. It's also at the top of the current embankment - so I wondered
if the railway had been shifted slightly eastwards too to allow it to
drop downwards. Of course, it could just be something entirely
uninteresting! It just looks a little platform-like.

There are some photos that might help at:
http://www.subbrit.org.uk/sb-sites/s...ad/index.shtml

Wow. It's hard to imagine that area *without* the Shepherd's Bush
Roundabout, as those pics and map show. It having been there the whole
of the time I've lived in London (20 years) and being so big and
important, you kind of imagine it's always been there!

Peter Frimberly wrote:
On Fri, 17 Mar 2006 13:44:19 +0000, Paul Terry
wrote:

In message , Dave Arquati
writes

I should make clear that it's not a *huge* drop - about three
metres I guess. It's also at the top of the current embankment -
so I wondered if the railway had been shifted slightly eastwards
too to allow it to drop downwards. Of course, it could just be
something entirely uninteresting! It just looks a little
platform-like.

There are some photos that might help at:
http://www.subbrit.org.uk/sb-sites/s...ad/index.shtml

Wow. It's hard to imagine that area *without* the Shepherd's Bush
Roundabout, as those pics and map show. It having been there the
whole of the time I've lived in London (20 years) and being so big
and important, you kind of imagine it's always been there!

I remember that roundabout being built in the early 70s. I don't see any
reason why the railway would have needed to be lowered or shifted east.
The whole area was cleared apart from the existing roads, and the
roundabout constructed from scratch, including two new bridges over the
railway either side of the Uxbridge Road. The roundabout is quite a bit
higher than the Uxbridge Road towards Shepherds Bush, and I particularly
remember the slope between the two being constructed, apparently by
laying huge thicknesses of tarmac on top of the existing road.

It's possible of course that the new bridges were built with enough
headroom for OHLE in the future. It was only a few years after the WCML
electrification, and I don't think the WLL had the DC third rail in
those days, so OHLE would have seemed the logical way forward.
--
Richard J.
(to e-mail me, swap uk and yon in address)

In article ,
(Richard J.) wrote:

It's possible of course that the new bridges were built with enough
headroom for OHLE in the future. It was only a few years after the
WCML electrification, and I don't think the WLL had the DC third rail
in those days, so OHLE would have seemed the logical way forward.

WLL electrification came many years later.

--
Colin Rosenstiel

Peter Frimberly wrote:

When I lived in Newcastle (admittedly 15 years ago) it was a fairly
standard occurence that the Metro line would be closed for a few days
on one of the sections around Longbenton, Wallsend, or Pelaw, because
someone had hooked a landrover to the signal cabling in the troughs or
the catenary and pulled massive lengths of it out/down in order to
steal it for scrap.

I don't live there any more so don't know if it still goes on.

Presumably not, in those days scrap metal was worth something!

On 16 Mar 2006 06:29:12 -0800, "TheOneKEA"
wrote:


Dave Arquati wrote:
In case anyone is interested, progress on this is now truly underway,
with work going on from the northbound carriageway of the West Cross
Route to clear the area below for the southbound platform, and what
looks like preparatory work to lower the embankment on the northbound side.

Is there any sign of extension to the OHLE? It has always been said
that the stop at Mitre Bridge Junction to change voltage eats paths.
Extending the OHLE to the new station and allowing the voltage change
to occur during station duties a la Farringdon would be sensible IMO.

The original thread about the new WLL line seems to have mostly
disappeared from my news service now, but I was passing the site today
and took a few pictures of how the excavations are going: see
http://www.ian-n.com/whitecity.

They're taken on my camera phone as that's all I had with me, but
they're not bad.

I also went round to the other side of the site, and grabbed a shot of
the new H&C line bridge, and peered over in to the Central Line tracks
and saw some new track work presumably something to do with the
revised depot layout.