Forth road bridge closure

[219]

Wonder if they've x-rayed any of the other 15 to see if they're also cracked?

I had that very thought the day this was announced : a pal used to be an industrial radiographer and spent his time checking ( mainly ) concrete supports for bridges and the like .

I thought there was more than one of these pieces affected , was six defective ones not mentioned ?

Sir William will truly be spinning in his grave .

 

[219]

The Forth Road Bridge was built 50 years ago, for 50 years ago traffic volumes and built out of whatever was the best materials available at the time. The same analogy could be said of the M1, built over 50 years ago for 50 years ago traffic volumes and the M1 is hopelessly outdated . In fact most of the motorways in the UK are running at full to overload most of the time, every day there are queues and they really need at least 4 lanes to cope, who could have ever expected the volume of traffic that is encountered in 2015 to be so great, and of course it will only get worse. Is it time to restrict the numbers of vehicles available in the country? but that can be another topic for discussion.

.

Only 30 years ago they thought we'd all be driving flying DeLoreans and riding hoverboards by now .

That , of course , was before JZ met his demise .

 

[grober]

I had that very thought the day this was announced : a pal used to be an industrial radiographer and spent his time checking ( mainly ) concrete supports for bridges and the like .

Every time I hear industrial radiography I get shivers down my spine. Heard too many stories about inadvertant exposure to GAMMA sources for comfort. Get it wrong just once and you're dead- and not in a good way.

 

[D-18]

A friend sent me a short verse in the style of the Scottish poet McGonagall lauding the Dear Leaderette's engineering credentials:

As i wis walkin doon the brig
A bit fell aff
Shyte.

 

[grober]

Giant crane arrives on site on a barge with two tugs.- may have been diverted from the new bridge site??

 

[grober]

FMQs: Nicola Sturgeon under fire over Forth Road Bridge - The Scotsman

 

[Druk]

FMQs: Nicola Sturgeon under fire over Forth Road Bridge - The Scotsman

An dth efat ugly one has the temerity to say... “I don’t think the First Minister can avoid the fact that the budget for the Forth Road bridge was hammered.”

As if her lot would have spent a bean more. NOT.

 

[Mr Kripling]

...the fat ugly one...

Can you narrow it down a bit?

 

[grober]

https://www.youtube.com/user/ScottishParl

I don't want this thread to degenerate into political name calling. I include these posts as background information for people to make up their own minds as to whether this was a preventable problem or simply something the ravages of time made inevitable. Its political with a small " p" sure but has relevance to many motorists in Scotland and perhaps for the many heading North during the festive season so it would be a pity if it was closed.

 

[Druk]

https://www.youtube.com/user/ScottishParl

I don't want this thread to degenerate into political name calling. I include these posts as background information for people to make up their own minds as to whether this was a preventable problem or simply something the ravages of time made inevitable. Its political with a small " p" sure but has relevance to many motorists in Scotland and perhaps for the many heading North during the festive season so it would be a pity if it was closed.

Appreciate that Graham Thanks and sorry for the diversion. (pun there, did you spot it?)

Can you narrow it down a bit?

Follow Grober's link FMQs: Nicola Sturgeon under fire over Forth Road Bridge - The Scotsman
then Google that responsible for the quote.



.

 

[Mike Walker]

Apologies if this has been mentioned earlier but it would be interesting, from a "Structural Engineering" viewpoint to know the following:-

1. Original design life assumed.
2. Original loadings allowed for.
3. Current maintenance strategy and inspection periods.
4. Current vehicular loadings.

Not ignoring the cost issues at all but the sad fact is that the applied loads are likely to be way above what was originally allowed for, and the impact of that can be seen now. Cracking such as this is possibly caused by fatigue, which can happen without warning hence the need to close the bridge and undertake repairs and further comprehensive investigations/surveys. Not easy of course at this time of year.

 

[grober]

Originally envised 30,000 vehicles per day per carriageway now running at approx 60,000 vehicles per day per carriageway. Not sure of the design life but 120 year figure at its design loading quoted .

 

[Charles Morgan]

60000 rather larger and heavier vehicles too.

 

[Mike Walker]

Exactly and the "fatigue" issue is a complex one that was probably not understood at original design stage.

 

[cb1965]

Should have got Brunel to build it. His Tamar Bridge has suffered no serious structural issues since it was opened in 1859 and requires nothing more than routine maintenance. Even the track bed has only needed replacing twice in 150 years!

 

[Bellow]

Should have got Brunel to build it. His Tamar Bridge has suffered no serious structural issues since it was opened in 1859 and requires nothing more than routine maintenance. Even the track bed has only needed replacing twice in 150 years!

He'd been dead 100 years.

I'm not sure why this is newsworthy. It's in Scotland so who cares?

Anyway, what do you care?...

 

[cb1965]

He'd been dead 100 years.

Really? I didn't know!

Anyway, what do you care?...

REMOVED

 

[grober]

Should have got Brunel to build it. His Tamar Bridge has suffered no serious structural issues since it was opened in 1859 and requires nothing more than routine maintenance. Even the track bed has only needed replacing twice in 150 years!

Bit like the Forth Rail bridge then! Unfortunately the nearby Tamar suspension road bridge had to have its entire concrete deck replaced with steel in the 90's. https://en.wikipedia.org/wiki/Tamar_Bridge.
It begins to look as if suspension bridges designed to move as part of their inherent design characteristics are much more likely to break down when faced with loadings far in excess of their initial design

 

[cb1965]

Bit like the Forth Rail bridge then! Unfortunately the nearby Tamar suspension road bridge had to have its entire concrete deck replaced with steel in the 90's. https://en.wikipedia.org/wiki/Tamar_Bridge.
It begins to look as if suspension bridges designed to move as part of their inherent design characteristics are much more likely to break down when faced with loadings far in excess of their initial design

Interestingly the Forth Bridge, to give it its correct name, was designed in the main by John Fowler who succeeded Brunel as chief engineer on the Great Western Railway in 1859 following the great man's death!

As for suspension bridges designed to move your theory is probably correct due to the additional movement from the additional loads leading to stress and metallurgical property changes that come with that over time especially where metal has been formed by various processes during manufacture. You see the same issues in airliners where the wings join the fuselage.

 

[grober]

http://www.atkinsglobal.com/~/media...-expansion-joints-onthe-forth-road-bridge.pdf