Hacker News Reader

Comment by zitterbewegung | Hacker News Reader

There is no bridge design that can be practically created and stop a multi ton shipping vessel. If you want to design something that can't then the solution would be to create a underground tunnel instead and this is much more expensive such as the channel tunnel https://en.wikipedia.org/wiki/Channel_Tunnel#:~:text=The%20C....

View on HN

There are already two tunnels underneath Baltimore Harbor. When they built the Key Bridge, they didn’t have the money to build another tunnel.

Situations like this might be the best time to make meaningful change. The "outcome to avoid" is front and center in everyone's mind, but no decision makers were at fault.

If this was a bridge collapse that could have been prevented with proper maintenance, there would be a lot more panic-induced buck passing.

EDIT: nevermind the article is terrible

I’m neither an engineer nor an architect, so this may come off as incredibly naive, but why wouldn’t layers of reinforcement — eg a retaining wall or guardrail — some distance out and around the main pillars help mitigate this kind of risk?

It would. Places, where rivers freeze, manage to build bridges that do not get crushed by the moving ice using this technology.

The amount of force involved is much greater than involved with moving ice.

Yeah the condition is irrelevant there, bad photo/timing for this article. Just trying to drum up fear.

I would describe that article as more of a call-to-action than drumming up fear. The article is quite clear that the problem in this particular case was due to design. On top of that, there was no suggestion that it was a faulty design. Rather, it's design does not reflect the realities of today.

I am not suggesting the article is perfect. There are lingering questions about which types of bridges fit in that 7.5%. Not all bridges have to deal with shipping traffic, heavier vehicles, or even more traffic. There are also questions as to why such large ships were permitted to pass under the bridge if it did not fit the design parameters of the bridge. But that is more indicative of an incomplete analysis rather than of fear mongering.

That bridge brand new, same result.

People see the headline and the image and walk away misinformed.

These ships have the mass of a skyscraper. Building a bridge you can throw a apartment building at doesn't make sense even if it was possible.

If we can't find crews who can manage this, we may need to pay them more and have higher standards for them.

This is a ship problem not a bridge problem.

The above post is somewhere between flat out wrong and malicious misinformation.

One can easily reinforce the pries of the bridge to ensure that any ship is deflected. The Francis Scott Key Bridge didn't implement these because it was deemed too expensive.

You have a funny definition of easily. The impact force has been estimated as between 120MN and 230MN. I doubt there exist many bridges that can take that hit. The kind of ship impact protection that bridges usually have are not built to take a 150000t ship at 8kn.

Bridges can be designed to handle that kind of collision. This article discusses some of the ways it can be done [1].

[1] https://www.cbsnews.com/news/how-to-protect-bridges-from-shi...

From the article :

Theoretically, you could build a structure that would never fail, but you'd have to put infinite money into it. For a critical bridge of this type, we would consider an acceptable chance for failure to be 1 in 10,000 years.

And at that point why not do a cost benefit analysis of a tunnel?

Reply on news.ycombinator.com