Naked Science Forum

Non Life Sciences => Technology => Topic started by: techmind on 28/09/2008 13:32:02

Title: How did they put the top on this bridge?
Post by: techmind on 28/09/2008 13:32:02

Since moving to Cambridge in August, I've been watching them build this bridge on the new Addenbrookes access-road.

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As at 25 Aug.

I'm fairly sure the triangular concrete bits were cast in-situ using wooden frames.

Title: How did they put the top on this bridge?
Post by: techmind on 28/09/2008 13:34:29

... but how did they put the top (horizontal) bit on?

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as at 21st Sept.

It's right above the railway, so it'd have to be fairly quick.
And I'm sure you'd need an unfeasably huge crane to lift that amount of concrete.

So how did they do it?

Title: How did they put the top on this bridge?
Post by: techmind on 28/09/2008 13:35:58

Bonus picture

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Title: How did they put the top on this bridge?
Post by: chris on 28/09/2008 17:10:03

Is it definitely made from concrete? Not steel box or similar?

Title: How did they put the top on this bridge?
Post by: decepticon on 28/09/2008 17:44:44

i would doubt the deck is made from one big slab of concrete but made up from several precast concrete beams which would be individually lifted and an insitu deck laid over the top to form road surface.
im more amazed that those massive concrete triangles have not toppled over when formwork was removed.
cheers
neil

Title: How did they put the top on this bridge?
Post by: lightarrow on 28/09/2008 19:53:59

Quote from: decepticon on 28/09/2008 17:44:44

i would doubt the deck is made from one big slab of concrete but made up from several precast concrete beams which would be individually lifted and an insitu deck laid over the top to form road surface.
im more amazed that those massive concrete triangles have not toppled over when formwork was removed.
cheers
neil

Don't know, is it possible they added ground under it from the left, at the same time removing formwork piece by piece from the left?

Title: How did they put the top on this bridge?
Post by: LeeE on 28/09/2008 21:50:53

I reckon they probably used several sub-unfeasibly large cranes to do it.

Title: How did they put the top on this bridge?
Post by: DoctorBeaver on 28/09/2008 22:19:33

Quote from: LeeE on 28/09/2008 21:50:53

I reckon they probably used several sub-unfeasibly large cranes to do it.

Yup

Title: How did they put the top on this bridge?
Post by: daveshorts on 29/09/2008 17:51:34

I think they probably could have done it in one piece using two infeasibly large cranes - which you can see in the first photo. large cranes can carry 2-300 tonnes each at least. I would have thought that this is probably enough to do it in one, and you could probably get it up there on a weekend or even a day.

Title: How did they put the top on this bridge?
Post by: techmind on 29/09/2008 20:49:14

I wonder if the construction of this bridge goes part way to explaining the closure of the railway between Royston and Cambridge, on various Sundays recently...

Title: How did they put the top on this bridge?
Post by: techmind on 29/09/2008 20:56:54

Quote from: decepticon on 28/09/2008 17:44:44

I'm more amazed that those massive concrete triangles have not toppled over when formwork was removed.

Me too. I don't -yet- see the point of them (if you'll excuse the pun).

Title: How did they put the top on this bridge?
Post by: daveshorts on 29/09/2008 21:45:03

I think they are there to increase the maximum slope of the pile of soil creating the onramp, otherwise it would flow down onto the railway.

The other reason they have been stopping the railway is for the construction of the misguided bus

Title: How did they put the top on this bridge?
Post by: DoctorBeaver on 30/09/2008 08:17:32

Quote from: daveshorts on 29/09/2008 21:45:03

The other reason they have been stopping the railway is for the construction of the misguided bus

Now you've got me pondering the possibilities of a misguided bus. Does it still believe in Santa, possibly? Or that the LibDems will win the next General Election?

Title: How did they put the top on this bridge?
Post by: techmind on 30/09/2008 23:36:37

What's the theory behind misguided buses? I mean the proponents' theory?

The council in Crawley has been very keen on them too.
They still require a driver, so the self-guiding technical wizardry is completely unnecessary - they could run equally well on a painted lane (or conventional dedicated road) with the driver doing the steering.

So why do they spend vast sums of money rebuilding roads with special curbs. What is the supposed point?

Misguided? I suspect so.