In article , (Roland Perry)
wrote:

In message , at 12:41:12 on
Fri, 13 Jan 2012, Paul Scott remarked:
A steady seepage of salt water into the structure, built in the 1960s,
has weakened the structure, but engineers said it was now safe to take
light traffic.

But no, the cheaper but potentially very damaging rock salt was used,
and this is what has caused the problems with the pre-stressing cables
within the concrete structure.

Presumably this isn't the only structure of this type on the road
network though?

Are many more due to be found before long?

There were extensive repairs to the M6 viaduct in the Castle Bromwich
area a couple of years ago, and the A14 flyover across Huntingdon
station is widely regarded as being about to fall down. One of the
bridges at the M6/M1 junction was replaced very recently.

http://www.bbc.co.uk/news/uk-england-16460505

Not sure how many of these are salt related.

Huntingdon viaduct already relies on extensive supplementary steelwork to
support it. Try driving underneath it to and from Hinchingbrooke sometime or
see http://snipurl.com/21owm92 [maps_google_co_uk].

--
Colin Rosenstiel

In message , Bruce
writes

So Hammersmith is very much a one-off. That doesn't mean that other
structures don't have problems of their own, but the design and
subsequent operation and maintenance practice related to the
Hammersmith flyover seems to have combined in a way that could only
end in tears.

No matter. There's little doubt that the prospect of all those Olympic
athletes and officials setting out in their limousines from Heathrow,
only to encounter the traffic jams that those of us who live in the area
currently suffer, will ensure that it is all fixed in record time.
--
Paul Terry

Paul Terry wrote:
In message , Bruce
writes

So Hammersmith is very much a one-off. That doesn't mean that other
structures don't have problems of their own, but the design and
subsequent operation and maintenance practice related to the
Hammersmith flyover seems to have combined in a way that could only
end in tears.

No matter. There's little doubt that the prospect of all those Olympic
athletes and officials setting out in their limousines from Heathrow,
only to encounter the traffic jams that those of us who live in the area
currently suffer, will ensure that it is all fixed in record time.


If it is for the Olympics, it will be Money No Object.

In message , at 12:36:40
on Fri, 13 Jan 2012, remarked:
There were extensive repairs to the M6 viaduct in the Castle Bromwich
area a couple of years ago, and the A14 flyover across Huntingdon
station is widely regarded as being about to fall down. One of the
bridges at the M6/M1 junction was replaced very recently.

http://www.bbc.co.uk/news/uk-england-16460505

Not sure how many of these are salt related.

Huntingdon viaduct already relies on extensive supplementary steelwork to
support it.

But why does it *need* the support? Is the underlying issue one of salt
corrosion.
--
Roland Perry

On Fri, 13 Jan 2012 13:09:44 +0000, Roland Perry
wrote:



There were extensive repairs to the M6 viaduct in the Castle Bromwich
area a couple of years ago, and the A14 flyover across Huntingdon
station is widely regarded as being about to fall down. One of the
bridges at the M6/M1 junction was replaced very recently.

I recall the Sunday Times getting excited about the M6 viaducts being
at risk of collapse in Birmingham, must have been in the 1970s or
'80s. The recent works are the second time they have had a thorough
going over that I am aware of.
The M6 bridge over the M1 was propped about 10 years ago. I don't know
what weakened it: poor design, over-use or salt, could have been any
of them.

Peter Johnson wrote:
On Fri, 13 Jan 2012 13:09:44 +0000, Roland Perry
wrote:
There were extensive repairs to the M6 viaduct in the Castle Bromwich
area a couple of years ago, and the A14 flyover across Huntingdon
station is widely regarded as being about to fall down. One of the
bridges at the M6/M1 junction was replaced very recently.

I recall the Sunday Times getting excited about the M6 viaducts being
at risk of collapse in Birmingham, must have been in the 1970s or
'80s.


80s. The problem was that the client deleted the sliding bearings
that were needed to allow for movement, including thermal expansion
and contraction, and replaced them with grease. Literally.

Within months, the grease dried out and the beams seized on to their
supports. So movement was no longer possible and temperature changes
put massive stresses into the structure.


The M6 bridge over the M1 was propped about 10 years ago. I don't know
what weakened it: poor design, over-use or salt, could have been any
of them.


As with many highway structures, the vast increase in the allowable
gross weight of the biggest lorries has created no end of problems.
The damage done to the road itself is proportional to the fourth power
of the axle weight of the vehicle. There must be a comparable
relationship between gross vehicle weight and the effect on
structures.

In article , (Roland Perry)
wrote:

In message , at
12:36:40 on Fri, 13 Jan 2012, remarked:

Huntingdon viaduct already relies on extensive supplementary steelwork to
support it.

But why does it *need* the support? Is the underlying issue one of
salt corrosion.

I don't think so. I think it's to do with the quality of the original
concrete construction.

--
Colin Rosenstiel

On Sat, 14 Jan 2012 15:34:09 -0600,
wrote:

In article , (Roland Perry)
wrote:

In message , at
12:36:40 on Fri, 13 Jan 2012, remarked:

Huntingdon viaduct already relies on extensive supplementary steelwork to
support it.

But why does it *need* the support? Is the underlying issue one of
salt corrosion.

I don't think so. I think it's to do with the quality of the original
concrete construction.

I don't think that it's just the concrete, it's a broader design
concept than that;

http://londonist.com/2012/01/will-so...th-flyover.php

E&OE etc.
JonH

In article ,
() wrote:

On Sat, 14 Jan 2012 15:34:09 -0600,
wrote:

In article ,
(Roland Perry) wrote:

In message , at
12:36:40 on Fri, 13 Jan 2012, remarked:

Huntingdon viaduct already relies on extensive supplementary steelwork
to support it.

But why does it *need* the support? Is the underlying issue one of
salt corrosion.

I don't think so. I think it's to do with the quality of the original
concrete construction.

I don't think that it's just the concrete, it's a broader design
concept than that;


http://londonist.com/2012/01/will-so...wrong-with-the
-hammersmith-flyover.php

E&OE etc.

Thanks for the link to an interesting article (with a few errors picked up
in the comments) but I was referring to quite a different structure on the
A14.

--
Colin Rosenstiel

wrote:

On Sat, 14 Jan 2012 15:34:09 -0600,
wrote:

In article , (Roland Perry)
wrote:

In message , at
12:36:40 on Fri, 13 Jan 2012, remarked:

Huntingdon viaduct already relies on extensive supplementary steelwork to
support it.

But why does it *need* the support? Is the underlying issue one of
salt corrosion.

I don't think so. I think it's to do with the quality of the original
concrete construction.

I don't think that it's just the concrete, it's a broader design
concept than that;

http://londonist.com/2012/01/will-so...th-flyover.php

E&OE etc.


Errors and Omissions Excepted??

There are plenty of potential errors in that article, but no
omissions. Rarely have I seen someone make such a complex explanation
of a very simple problem. Probably due to his lack of knowledge of
this particular structure, the author seems to have wanted to cover
all the possible problems in all possible concrete bridge structures.
Perhaps he did omit two possibilities - cosmic rays and UFO impact.
And then there's terrorist attack, so let's make that three. ;-)