On Thu, 19 Nov 2009 10:14:48 +0000, "J. Chisholm"
wrote:
I don't go with 'constant change' theory. More like a typical foundation
that has been undermined by a particular rainfall event.


That's precisely why I stated "It is probably a result of scour under
the foundations as a result of the extreme flows of water."

You obviously didn't bother to read that. However, you quoted it in
your reply.

Do you make a habit of replying to postings you cannot be bothered to
read? Why?

Bruce wrote:
On Thu, 19 Nov 2009 10:14:48 +0000, "J. Chisholm"
wrote:
I don't go with 'constant change' theory. More like a typical foundation
that has been undermined by a particular rainfall event.


That's precisely why I stated "It is probably a result of scour under
the foundations as a result of the extreme flows of water."

You obviously didn't bother to read that. However, you quoted it in
your reply.

Do you make a habit of replying to postings you cannot be bothered to
read? Why?

Sorry. No need to be agressive... I read the last para which implied a
different mode of failure, although I support the fact that modern
bricks and cement based motors, result in increased cracking. I was
always told that mortar is to keep bricks apart, not to stick therm
together.
I think engineers are going back to lime based mortars in many
applications where twenty years ago they would have used cement based
ones without a thought.

Jim

"Bruce" wrote in message
...
On Wed, 18 Nov 2009 23:18:36 GMT, "Richard J."
wrote:

You're talking as though the problem is insufficient brickwork at the
top of the arch. But it's clear from the photo that the failure occurred
lower down, where a great mass of brickwork has moved. Looks like a
gross failure of the foundations.


Indeed it does. It is probably a result of scour under the
foundations as a result of the extreme flows of water.


There are suggestions doing the rounds that this structure wasn't built as a
water course, but as a 'subway' under Feltham Yard when first built. There
is a second course of the River Crane under the tracks further east, next to
the recently built PO sorting office.

As a non expert, I'm wondering if the foundations for a subway would meet
the requirements for a culvert.

OTOH if it was built as a culvert, maybe the majority of the flow now goes
through this route, as it is much straighter than the other?

Paul

J. Chisholm wrote on 19 November 2009 12:13:06 ...
Bruce wrote:
On Thu, 19 Nov 2009 10:14:48 +0000, "J. Chisholm"
wrote:
I don't go with 'constant change' theory. More like a typical foundation
that has been undermined by a particular rainfall event.

That's precisely why I stated "It is probably a result of scour under
the foundations as a result of the extreme flows of water."

You obviously didn't bother to read that. However, you quoted it in
your reply.

Do you make a habit of replying to postings you cannot be bothered to
read? Why?

Sorry. No need to be agressive... I read the last para which implied a
different mode of failure,

But the "last para" was in response to my speculation about what led to
the earlier brickwork replacement at the top of the arch, i.e. a
different event to the recent collapse.

Incidentally, was the rain in the Feltham area really that extreme last
week? (I was several hundred miles away at the time.)

There is another photo, of unsupported track, presumably above a point
further along the tunnel, at

http://rail-news.com/wp-content/uplo...Feltham-v2.jpg

(The report containing that photo is at
http://rail-news.com/2009/11/17/100-...-flood-damage/
)
--
Richard J.
(to email me, swap 'uk' and 'yon' in address)

On Thu, 19 Nov 2009 12:02:05 -0000, "Paul Scott"
wrote:
"Bruce" wrote in message
.. .
On Wed, 18 Nov 2009 23:18:36 GMT, "Richard J."
wrote:

You're talking as though the problem is insufficient brickwork at the
top of the arch. But it's clear from the photo that the failure occurred
lower down, where a great mass of brickwork has moved. Looks like a
gross failure of the foundations.


Indeed it does. It is probably a result of scour under the
foundations as a result of the extreme flows of water.


There are suggestions doing the rounds that this structure wasn't built as a
water course, but as a 'subway' under Feltham Yard when first built. There
is a second course of the River Crane under the tracks further east, next to
the recently built PO sorting office.

As a non expert, I'm wondering if the foundations for a subway would meet
the requirements for a culvert.


Probably not. There would be no requirement for the foundations of a
subway to be designed to resist the scouring action of flowing water.

There are suggestions doing the rounds that this structure wasn't built as a
water course, but as a 'subway' under Feltham Yard when first built. There
is a second course of the River Crane under the tracks further east, next to
the recently built PO sorting office.

As a non expert, I'm wondering if the foundations for a subway would meet
the requirements for a culvert.

Probably not. *There would be no requirement for the foundations of a
subway to be designed to resist the scouring action of flowing water.

Was there a plan to run the London LOOP walking route under Feltham
Yard? I remember having to make a long detour through Hounslow Heath
and through Whitton to get back to the river. It would seem a good
time to get a new subway built while they're replacing it, since I
doubt the LOOP could have justified it on its own.

Perhaps it was hiking extremists who caused the flood damage by
blocking up the other course!

"Paul Terry" wrote in message
...
In message , Paul Scott
writes

There are suggestions doing the rounds that this structure wasn't built as
a
water course, but as a 'subway' under Feltham Yard when first built.

No, the subway (in fact there appears to be two) runs parallel with the
river tunnel, as seen he http://www.geograph.org.uk/photo/108858

Right - well done for finding those pictures. I wonder if that more modern
looking ramped access visible in the various aerial view sites, eg Multimap,
just provides an access into the RH of the two smaller tunnels shown he
http://www.geograph.org.uk/photo/366747
to reduce its effective length, ie just to get under the railway?

I wonder if diverting the mill stream caused greater flow in the main
channel, exacerbating the problem?

AIUI the main flow will follow the path of least resistance. I imagine
under the conditions of heaviest rainfall the Crane drains surface run off
from a vast area?

Another possibility is that the smaller tunnels were some sort of flood
channel of course, as originally built.

Paul S

In message , Paul Terry
writes

No, the subway (in fact there appears to be two) runs parallel with the
river tunnel, as seen he http://www.geograph.org.uk/photo/108858

Sorry, that's the wrong URL. It should be:

http://www.geograph.org.uk/photo/366747
--
Paul Terry

In message , Paul Scott
writes

Right - well done for finding those pictures. I wonder if that more modern
looking ramped access visible in the various aerial view sites, eg Multimap,
just provides an access into the RH of the two smaller tunnels shown he
http://www.geograph.org.uk/photo/366747
to reduce its effective length, ie just to get under the railway?

I actually gave the wrong URL for the first photo, but you have quite
rightly spotted the correct one.

Yes, I think the ramp simply goes down to the old foot tunnel, which is
why someone earlier in the thread couldn't see where what appeared to be
a pedestrian subway emerged.

AIUI, there is a footpath above the pedestrian tunnel (which provides a
viable alternative to the long, unlit tunnel), and the ramp was put in
to take pedestrians down to the one bit of tunnel that is still used,
beneath the railway line. The Google satellite image shows this path
quite clearly.

AIUI the main flow will follow the path of least resistance. I imagine
under the conditions of heaviest rainfall the Crane drains surface run off
from a vast area?

I suspect that, like a lot of London's smaller rivers, it takes a huge
amount of surface water when the drains can't cope in heavy rain. The
Environment Agency's flood map shows the banks of the Crane (and its
tributary, the Yeading) virtually all the way from Northolt to
Twickenham.

Interestingly, the same map indicates little or no flood risk for the
mill stream on Hounslow Heath, which I presume means that it is now
pretty much cut off from the main channel. This again could have been a
contributory factor to the bridge collapse on the main channel.

Another possibility is that the smaller tunnels were some sort of flood
channel of course, as originally built.

At least one of them might have been - I can't see any reason for two
parallel foot tunnels. If so, their closure (probably dating back to
when the marshalling yard was built) would certainly have exacerbated
the problem.

--
Paul Terry

On Wed, 18 Nov 2009, Bruce wrote:

On Fri, 20 Nov 2009 02:07:19 -0600,
wrote:

Hmm. Looks to me like part of the top of the arch was filled with rubble.
LSWR jerry building?

The spandrels were always filled with rubble.

Next question?

Now that it's failed, does that make it a cockup spandrel?

tom

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Tubes are the foul subterranean entrails of the London beast, stuffed
with the day's foetid offerings. -- Tokugawa