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And that structure probably existed because the bridge has fewer longer spans, probably since the seabed below the bridge is deeper (and needs to be deeper to s

And that structure probably existed because the bridge has fewer longer spans, probably since the seabed below the bridge is deeper (and needs to be deeper to support container ships passing below). The Öresundsbron (connecting Sweden and Denmark) features both short segments but also with an overhand section in the middle for larger ships to pass through. (1) The great belt bridge (inside Denmark) is slightly higher but has the same kind of profile, one of the largest cruise ships barely making it under it is shown passing in the video below (2). I think the simple truth is that we're vulnerable to these kinds of accidents unless we build far far sturdier bridges, but at these scales to allow passage of ships of these sizes the cost would just make many bridge projects prohibitably expensive. 1: https://www.norden.org/sites/default/files/styles/content_size_800/public/2021-03/%C3%98resund.jpg?h=0583ede9&itok=vfdhJoKL https://www.norden.org/sites/default/files/styles/content_si... 2: https://www.youtube.com/watch?app=desktop&v=j1Cs0C8LkeU https://www.youtube.com/watch?app=desktop&v=j1Cs0C8LkeU

Symbiote 3y ago
The Øresundsbron is a bridge and a tunnel, and although it's not required most ships choose to cross over the tunnel rather than under the bridge. I was curious about Zealand's other connection, the Great Belt Fixed Link: > The West Bridge has been struck by sea traffic twice. While the link was still under construction on 14 September 1993, the ferry M/F Romsø drifted off course in bad weather and hit the West Bridge. At 19:17 on 3 March 2005, the 3,500-ton freighter MV Karen Danielsen crashed into the West Bridge 800 metres from Funen. All traffic across the bridge was halted, effectively cutting Denmark in two. The bridge was re-opened shortly after midnight, after the freighter was pulled free and inspectors had found no structural damage to the bridge. > The East Bridge has so far been in the clear, although on 16 May 2001, the bridge was closed for 10 minutes as the Cambodian 27,000-ton bulk carrier Bella was heading straight for one of the anchorage structures. The ship was deflected by a swift response from the navy. In Danish [2], but it looks like there's someone always monitoring the sea traffic, and able to close the bridge at very short notice — I assume with the red flashing lights which are used to close motorways in emergencies. > The eastern end through the Great Belt is international water, and therefore even the largest ships must be able to sail under the bridge. The 254 meter high pylons are therefore dimensioned so that they should be able to withstand the approach of tankers of 250,000 tonnes dead weight (DWT) at a speed of 10 knots. Artificial islands protect the anchor blocks as well as the three outermost piers on the Zealand side and the two outermost ones on the Sprogø side. [1] https://en.wikipedia.org/wiki/Great_Belt_Bridge https://en.wikipedia.org/wiki/Great_Belt_Bridge [2] https://web.archive.org/web/20090116051425/http://ing.dk/artikel/78326-storebaeltsbro-naer-paasejlet-af-fragtskib https://web.archive.org/web/20090116051425/http://ing.dk/art...
fl7305 3y ago
Öresundsbron is claimed to be designed to be resistant against ships hitting it. They have placed artificial underwater reefs around the pylons. The pylons themselves can also take quite a beating.
- Kye 3y ago
  The twin towers were designed to take a hit from an airliner and survive[0]. Sometimes even the best design fails when reality crashes into it. [0] They expected fuel leaking to cause a devastating fire, but not that the fire would weaken the structure enough to cause the cascade failure that brought the towers down. https://archive.seattletimes.com/archive/?date=19930227&slug=1687698 https://archive.seattletimes.com/archive/?date=19930227&slug...
  - AnimalMuppet 3y ago
    They survived for roughly an hour after the airliners hit. That hour let roughly 40,000 people make it out. The towers failed, in the end, but withstanding the initial hit mattered a lot.
    - Kye 3y ago
      That's great, but the topic is engineering things to survive serious damage, period. Not just long enough for people to escape before it succumbs. A failed structure is still a failed structure with all the socioeconomic trouble that entails.
      - fl7305 3y ago
        You're mixing up two different things. If the design requirement for the twin towers was "be fire resistant enough to let most people out of the building", then I'd say they met that requirement, right? If the design requirement for a bridge is "continue operating at normal capacity", then that is a very different requirement.
      - AnimalMuppet 3y ago

Symbiote 3y ago

The Øresundsbron is a bridge and a tunnel, and although it's not required most ships choose to cross over the tunnel rather than under the bridge. I was curious about Zealand's other connection, the Great Belt Fixed Link: > The West Bridge has been struck by sea traffic twice. While the link was still under construction on 14 September 1993, the ferry M/F Romsø drifted off course in bad weather and hit the West Bridge. At 19:17 on 3 March 2005, the 3,500-ton freighter MV Karen Danielsen crashed into the West Bridge 800 metres from Funen. All traffic across the bridge was halted, effectively cutting Denmark in two. The bridge was re-opened shortly after midnight, after the freighter was pulled free and inspectors had found no structural damage to the bridge. > The East Bridge has so far been in the clear, although on 16 May 2001, the bridge was closed for 10 minutes as the Cambodian 27,000-ton bulk carrier Bella was heading straight for one of the anchorage structures. The ship was deflected by a swift response from the navy. In Danish [2], but it looks like there's someone always monitoring the sea traffic, and able to close the bridge at very short notice — I assume with the red flashing lights which are used to close motorways in emergencies. > The eastern end through the Great Belt is international water, and therefore even the largest ships must be able to sail under the bridge. The 254 meter high pylons are therefore dimensioned so that they should be able to withstand the approach of tankers of 250,000 tonnes dead weight (DWT) at a speed of 10 knots. Artificial islands protect the anchor blocks as well as the three outermost piers on the Zealand side and the two outermost ones on the Sprogø side. [1] https://en.wikipedia.org/wiki/Great_Belt_Bridge https://en.wikipedia.org/wiki/Great_Belt_Bridge [2] https://web.archive.org/web/20090116051425/http://ing.dk/artikel/78326-storebaeltsbro-naer-paasejlet-af-fragtskib https://web.archive.org/web/20090116051425/http://ing.dk/art...

fl7305 3y ago

Öresundsbron is claimed to be designed to be resistant against ships hitting it. They have placed artificial underwater reefs around the pylons. The pylons themselves can also take quite a beating.

Kye 3y ago
The twin towers were designed to take a hit from an airliner and survive[0]. Sometimes even the best design fails when reality crashes into it. [0] They expected fuel leaking to cause a devastating fire, but not that the fire would weaken the structure enough to cause the cascade failure that brought the towers down. https://archive.seattletimes.com/archive/?date=19930227&slug=1687698 https://archive.seattletimes.com/archive/?date=19930227&slug...
- AnimalMuppet 3y ago
  They survived for roughly an hour after the airliners hit. That hour let roughly 40,000 people make it out. The towers failed, in the end, but withstanding the initial hit mattered a lot.
  - Kye 3y ago
    That's great, but the topic is engineering things to survive serious damage, period. Not just long enough for people to escape before it succumbs. A failed structure is still a failed structure with all the socioeconomic trouble that entails.
    - fl7305 3y ago
      You're mixing up two different things. If the design requirement for the twin towers was "be fire resistant enough to let most people out of the building", then I'd say they met that requirement, right? If the design requirement for a bridge is "continue operating at normal capacity", then that is a very different requirement.
    - AnimalMuppet 3y ago