Maintaining ageing road infrastructure

Cowley

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It’s a simple question with no doubt a very complicated answer...
We have many thousands of miles worth of motorways/dual carriageways etc in this country, with many of the concrete bridges/viaducts etc having been built in the past six or so decades, and we were probably in a heyday of road building from the late 1960s up to the early 1990s I guess?

I’ve been wondering recently though how long some of these structures can reasonably last?
Obviously there was the terrible bridge collapse in Genoa, Italy last year which shows how a flawed design and poor maintenance can cause a catastrophic failure:
https://en.m.wikipedia.org/wiki/Ponte_Morandi
That was an exceptional case obviously. However are we edging towards a time in perhaps thirty or forty years where a huge amount of the road networks infrastructure will need replacing as life expired?
I’m thinking of things like the elevated section of the M4 coming into London for instance.
I mean can you imagine the cost and disruption of replacing something like that?

I’m hoping some people on here might be knowledgeable on such things..?
 
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HOOVER29

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I was thinking what would happen if the elevated parts of Spaghetti junction near Birmingham wanted replacing. I passed under it not so long ago on the Cross-City line & close up it kinda looks ropey in parts. I’m no engineer so it might be rock solid. I’m just glad I don’t use it that often (maybe 4 or 5 times a year). After all surely concrete has a set lifespan. Some parts of concrete Plymouth are starting to look a bit past it.
Give it another 30 odd yrs & Milton Keynes will look the same. Parts of Birmingham a lot sooner.
 

thejuggler

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Glenfinnan viaduct has stood for almost 120 years. A testament to how long concrete can last.

All major highways structures receive regular inspections and repairs are then planned Unless there is an inherent consruction defect it is unlikely the whole of flyovers such as M4 or Spaghetti Junction would need complete replacement in one go. Tinsley viaduct has had major repairs over the years, but the M1 has remained open.
 

Geezertronic

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They always seem to be doing work on Spaghetti - it feels like a rolling maintenance schedule :)

They are also doing a lot (and causing a lot of disruption) doing repairs to the elevated section of the M5 by the junction with the M6. There is also a large elevated section between M6 J5 & J6
 

HOOVER29

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Yeah the M5 junction to the M6 is a right old mare at the moment. I went that way to Walsall last week & wished I hadn’t.
Normal journey time about 45 mins through shortcuts.
M42/M6/A34 took me 90 mins.
 

DarloRich

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I was thinking what would happen if the elevated parts of Spaghetti junction near Birmingham wanted replacing. I passed under it not so long ago on the Cross-City line & close up it kinda looks ropey in parts. I’m no engineer so it might be rock solid. I’m just glad I don’t use it that often (maybe 4 or 5 times a year). After all surely concrete has a set lifespan. Some parts of concrete Plymouth are starting to look a bit past it.
you would have to do what they do with the railways: take it under possession and rebuild trying while trying to keep the show on the road. No doubt you would try and do half the bridge at time.


Give it another 30 odd yrs & Milton Keynes will look the same. Parts of Birmingham a lot sooner.
which areas of MK are you thinking of?
 

HOOVER29

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I remember visiting the place years ago.
I’ve been driving over 33 yrs now so If my memory serves me well it would be around the late 80’s & the place was all roundabouts. I defo saw concrete & not those cows either.
Not been back since.
Not really wanted to to be honest
 

AM9

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Glenfinnan viaduct has stood for almost 120 years. A testament to how long concrete can last. ...
Here's an even blacker cat: The Pantheon in Rome was completed 1894 years ago!

Yet what must be one of the most treasured concrete creations in the UK, the listed Waterloo Bridge - opened in 1942!, looks none too smart when you walk under it on the South Bank path. Some of the cladding is crumbling and what seems like reinforcement bars can be seen.
 

Lucan

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Glenfinnan viaduct has stood for almost 120 years. A testament to how long concrete can last.
I understand that those early concrete structures are basically masonry designs - ie the concrete is entirely in compression and therefore does not rely (or even have?) any steel reinforcement. In that respect they are not much different from Roman structures, including arches, that have lasted 2000 years. It is the corrosion of the steel reinforcement that will limit the life of modern structures.

I have seen a claim that in 25,000 years time those early un-reinforced concrete viaducts will be the only non-trivial artifacts that will survive intact from our present day. Unlike the Roman arches and medieval bridges, which are assemblies of smaller blocks, they could even withstand large earthquakes.
 

Cowley

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As far as it goes with exposed and corroding reinforcement bars - is it possible to treat these with some kind of rust inhibiting compound and cover them back over with fresh concrete?
There must be some structures that were built in certain decades that are far more susceptible to concrete cancer than newer ones I’d assume?
 

DarloRich

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I remember visiting the place years ago.
I’ve been driving over 33 yrs now so If my memory serves me well it would be around the late 80’s & the place was all roundabouts. I defo saw concrete & not those cows either.
Not been back since.
Not really wanted to to be honest
well don't make silly statements then! It is a great town with an undeserved reputation built on such statements! Cant see much concrete in front of me today. MK Council have been pretty good at a rolling programme of removing and replacing older buildings. Your statement may well stand for other new towns but not, really, MK

@Bletchleyite or similar will know more.
 

edwin_m

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Quite a lot had to be done to the M6 around Washwood Heath, must be 15-20 years ago now. I think they had to replace all or part of each of the lateral beams that link the vertical columns and support the road. Most of the original bridges over the M1 still seem to be there now (the Marples Must Go type for anyone with a long memory).
 

HOOVER29

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Quite a lot had to be done to the M6 around Washwood Heath, must be 15-20 years ago now. I think they had to replace all or part of each of the lateral beams that link the vertical columns and support the road. Most of the original bridges over the M1 still seem to be there now (the Marples Must Go type for anyone with a long memory).
Some really ropey looking bridges towards the north end of the M1 around Leeds. Obviously they are still structurally sound otherwise they’d be road base by now.

I was down in Cornwall 3 wks ago & the A38 passing through Plymouth was an eye opener.
Again it must be ok otherwise they’d be hacking it down by now.
 

DelW

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As far as it goes with exposed and corroding reinforcement bars - is it possible to treat these with some kind of rust inhibiting compound and cover them back over with fresh concrete?
There must be some structures that were built in certain decades that are far more susceptible to concrete cancer than newer ones I’d assume?
There are specialist concrete repair contractors whose bread-and-butter job that sort of repair is. Around 15 years ago I was involved with such a company (they were part of the same group as my employer and I helped them set up a graduate training scheme). There are more sophisticated techniques as well, including passing electric currents through the reinforcement (but don't ask me to explain the chemistry).

The problem usually called "concrete cancer" (AKA alkali aggregate reaction - AAR, or alkali-silica reaction - ASR) mainly affects structures from the 1970s and 1980s when particular types of cement reacted with particular aggregates (often from the Thames Valley), but that became well understood quite quickly and has been avoided since that era.

The main problems with bridges of the last 50 years or so are around seized movement bearings, or corroded pre-stressing cables. In general those can be repaired, or the structure modified not to need them, although there are cases where demolition and reconstruction is a more economic option for extended life.

(I spent most of the 1970s and '80s building concrete bridges, and AFAIK they are still in good order!)
 

DarloRich

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It certainly applies to a lot of Scottish new towns (Glenrothes, Livingston, East Kilbride etc). I’m sure the people in these places are nice but from the outside they don’t look like appealing places.
it applies to the one lived in as a kid: Newton Aycliffe

But NOT MK

The problem usually called "concrete cancer" (AKA alkali aggregate reaction - AAR, or alkali-silica reaction - ASR) mainly affects structures from the 1970s and 1980s when particular types of cement reacted with particular aggregates (often from the Thames Valley), but that became well understood quite quickly and has been avoided since that era.

The main problems with bridges of the last 50 years or so are around seized movement bearings, or corroded pre-stressing cables. In general those can be repaired, or the structure modified not to need them, although there are cases where demolition and reconstruction is a more economic option for extended life.
A very good post.
 

Cowley

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There are specialist concrete repair contractors whose bread-and-butter job that sort of repair is. Around 15 years ago I was involved with such a company (they were part of the same group as my employer and I helped them set up a graduate training scheme). There are more sophisticated techniques as well, including passing electric currents through the reinforcement (but don't ask me to explain the chemistry).

The problem usually called "concrete cancer" (AKA alkali aggregate reaction - AAR, or alkali-silica reaction - ASR) mainly affects structures from the 1970s and 1980s when particular types of cement reacted with particular aggregates (often from the Thames Valley), but that became well understood quite quickly and has been avoided since that era.

The main problems with bridges of the last 50 years or so are around seized movement bearings, or corroded pre-stressing cables. In general those can be repaired, or the structure modified not to need them, although there are cases where demolition and reconstruction is a more economic option for extended life.

(I spent most of the 1970s and '80s building concrete bridges, and AFAIK they are still in good order!)
As above, great post DelW thanks for that.
 

175mph

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What makes me laugh is when people like my uncle insist that we, the UK has the world's worst condition roads, but when I tell them that from my experiences of traveling around different countries, certain parts of Russia have roads that are in such poor condition they make many of our bad roads seem like traveling across velvet carpets, he just ignores my point or gives me a look as if he thinks I'm deluded.
 

PeterC

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well don't make silly statements then! It is a great town with an undeserved reputation built on such statements! Cant see much concrete in front of me today. MK Council have been pretty good at a rolling programme of removing and replacing older buildings. Your statement may well stand for other new towns but not, really, MK

@Bletchleyite or similar will know more.
The only problem with MK is that people give you directions based on roundabout names but the council doesn't put these on the road signs. By the time you see the little plaque on the roundabout it is often too late to safely undertake the manouvre. Apart from that it isn't too bad although I haven't visited much since the M-i-L passed away.
 

Cowley

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eMeS

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I don’t know if anyone else watched this program about the Genoa Bridge collapse? ...
Yes, I did.
And back in 1969, 2 years after it was opened, we drove across the bridge and took photos. Even then my photos show that the deck was drooping away from the points of support - presumably because the axle weights were too high.
 

Cowley

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Yes, I did.
And back in 1969, 2 years after it was opened, we drove across the bridge and took photos. Even then my photos show that the deck was drooping away from the points of support - presumably because the axle weights were too high.
Interesting post eMeS.
 

Peter Mugridge

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Yes, I did.
And back in 1969, 2 years after it was opened, we drove across the bridge and took photos. Even then my photos show that the deck was drooping away from the points of support - presumably because the axle weights were too high.
Do you have the photos still? Would you be able to post them up on here?
 

talltim

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There’s also the other end of the scale, there’s miles of very minor roads, which while they don’t cost the same to maintain as the high profile structures, still have a very low CBR. If they were railways they’d have been closed years ago.
Been driving around Cornwall the last two weeks and our sat-nav seems to delight in taking us down the most minor roads. All of these probably need a twice yearly hedge cutting (if you’ve been on a minor road in Cornwall you’ll know what I mean) even if the tarmac lasts for years. Surely there should be a rolling program of closure of the duplicate routes?
 

edwin_m

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I don't see any expansion joints in that picture and a quick web search doesn't find any mention of whether they were provided. Is it possible that the "sag" shown is how the bridge coped with thermal expansion?
 

Tetchytyke

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I don’t know if anyone else watched this program about the Genoa Bridge collapse? But it’s quite interesting and raises a few interesting questions about ageing motorway bridges in the last ten minutes of the program.
A lot of these concrete bridges are going to have to be replaced long before it was expected to have to. It's the cable-staying in the concrete; there's no way of getting to the steel and it corrodes due to shoddy workmanship. We've seen it over here with the Forth Road Bridge and the Hammersmith Flyover; TfL under Boris left the flyover open knowing there was a risk of collapse.
 

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