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Author Topic: 3rd Bosphorus Bridge: what is the point of the suspension part?  (Read 579 times)

MCRoads

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Why not just do a cable-stayed bridge? Why have like a 1000 foot section be the entire point of the hybrid? If you are going to do a hybrid, why not make it half and half? Not 90/10?
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english si

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Re: 3rd Bosphorus Bridge: what is the point of the suspension part?
« Reply #1 on: March 24, 2018, 10:34:35 AM »

So the suspension cables from the towers hold up the middle, while cable stays hold the rest up.

It's a very tall bridge (only one whose structure is taller), and rather long too (not that many that have longer spans).

To have the whole bridge cables would need taller towers or a tower in the middle of the strait - neither really an option. Thus suspension is needed to fill in the middle (plus there were probably aesthetic reasons to go with a hybrid). But if cables can reach most of the way to the middle, then do that as it allows less load on the suspension cables. There's no reason why a hybrid needs to be 50/50 - that way lies nonsense.

BTW, the span is 4619ft, so 1000ft is over 20%. Looking at a picture it seems that about that isn't covered by the cables, but the suspension bridge bit overlaps, giving something more like 60/60 than 50/50 anyway.
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1995hoo

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Re: 3rd Bosphorus Bridge: what is the point of the suspension part?
« Reply #2 on: March 24, 2018, 11:49:56 AM »

The combination reminds me of the Brooklyn Bridge.
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Revive 755

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Re: 3rd Bosphorus Bridge: what is the point of the suspension part?
« Reply #3 on: March 24, 2018, 12:12:42 PM »

I think the better question is why not have it as a pure suspension bridge since the main span is about 2,000 feet shorter than the current record holder (Wikipedia list)?  Does it have to do with the railroad on the bridge?
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SteveG1988

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Re: 3rd Bosphorus Bridge: what is the point of the suspension part?
« Reply #4 on: March 27, 2018, 12:36:44 AM »

To flex their engineering muscles?
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english si

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Re: 3rd Bosphorus Bridge: what is the point of the suspension part?
« Reply #5 on: March 27, 2018, 06:33:32 AM »

Indeed, it's a statement piece, so asthetics and engineering prowess are more important than simple-and-cheap.
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SteveG1988

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Re: 3rd Bosphorus Bridge: what is the point of the suspension part?
« Reply #6 on: March 27, 2018, 06:00:00 PM »

Indeed, it's a statement piece, so asthetics and engineering prowess are more important than simple-and-cheap.

Yup, Flexing their muscles. "we can build this...so why not?" I mean, there are not many long span bridges to be built in the years going forward. We could see a long span bridge over the Delaware Bay, or the Long Island Sound bridge, or even the Raritan Bay bridge to staten island. And these are just the three most sane ones i could think up.
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Re: 3rd Bosphorus Bridge: what is the point of the suspension part?
« Reply #7 on: March 28, 2018, 12:11:35 AM »

Indeed, it's a statement piece, so asthetics and engineering prowess are more important than simple-and-cheap.

Yup, Flexing their muscles. "we can build this...so why not?" I mean, there are not many long span bridges to be built in the years going forward. We could see a long span bridge over the Delaware Bay, or the Long Island Sound bridge, or even the Raritan Bay bridge to staten island. And these are just the three most sane ones i could think up.
You're only thinking in the USA though. There are many gaps around the world, especially in countries with fjords or multiple islands.

english si

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Re: 3rd Bosphorus Bridge: what is the point of the suspension part?
« Reply #8 on: March 28, 2018, 04:51:04 AM »

Turkey is building at least one more transcontinental bridge outside of Istanbul (this time further south, across the Dardenelles).

China is building all sorts of massive bridges - not least the Hong Kong-Macau (plus branches) one.

Saudi Arabia want a bridge to Egypt, mostly to avoid and annoy Israel.

Western Europe seems to be going tunnels for new long crossings now. The Queensferry Crossing and Mersey Gateway that opened last year are big bridges that supplement and replace other ones that are in need of closure and repair - this is (with two or three possible exceptions) the future of long bridges in Europe.
« Last Edit: March 28, 2018, 05:01:18 AM by english si »
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SteveG1988

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Re: 3rd Bosphorus Bridge: what is the point of the suspension part?
« Reply #9 on: March 29, 2018, 07:28:23 AM »

Indeed, it's a statement piece, so asthetics and engineering prowess are more important than simple-and-cheap.

Yup, Flexing their muscles. "we can build this...so why not?" I mean, there are not many long span bridges to be built in the years going forward. We could see a long span bridge over the Delaware Bay, or the Long Island Sound bridge, or even the Raritan Bay bridge to staten island. And these are just the three most sane ones i could think up.
You're only thinking in the USA though. There are many gaps around the world, especially in countries with fjords or multiple islands.

I forgot about Slartibartfast's award winning work
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