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NTSB Recommends 68 Bridges in US be Evaluated for Risk of Collapse from Vessel Strike

Is it reasonable to assume that this could have terrorism implications? E.g terrorist hijack a shipping vessel with the intention of crashing the vessel in to supports of the Verrazano bridge or the San Francisco bay bridge.
 
Plenty of ships hit bridges without any terrorism. The Bay Bridge has already been hardened against collision after 9/11 but ships are 2-3x the size today vs 2001 and it's simply becoming impossible to protect bridges from so much energy.

A real solution is to require ships over a certain size to have tugboat escort when transiting under key bridges. A tug escort comes with a 6 knot speed limit.
 
I imagine a tug escort for container ships involves multiple tugs, therefore no single point failure either.
 
Tankers already require escorts when loaded. A single tug is used. The tug only expected to act as brakes or a rudder. The key is the speed limit. Tugs aren't effective above 6 knots. If we impose escort conditions on container ships they won't have so much energy, either.
 
If a ship is deliberately going to crash into a bridge, can a tug stop them?
 
No. The ships are faster than the tugs and when speeds exceed 6 knots the tug is using most of its power to traverse through the water and has little left to do any maneuvering of the ship. Certain designs of tugs with large skegs can exert very high braking forces at higher speeds but these tugs are not common in modern ports. We're more focused on how quickly we can get the ship to and from the dock.

A naval architect that I hold in very high regard did some studies. These have been impactful on the industry.


Sorry, scribd has turned to garbage like every other website.
 
Plenty of ships hit bridges without any terrorism. The Bay Bridge has already been hardened against collision after 9/11...

I didn't find any mention of this in the Wikipedia page for the bridge.........

I do know that the western span was real-life tested in 2007 by the Cosco Busan, and passed with flying colors. Evaluation of that event may have concluded that that bridge was "adequately protected". Which it was, in that particular case.

And it was tested again in 2013 by Overseas Reymar--passed again.



Looking at the Golden Gate bridge, the north tower is almost on land, and the south tower is nicely surrounded by a great hulking concrete wall. Might as well double check, but that bridge looks pretty safe.


spsalso
 
Remember that the Busan is less than half the weight of the Dali and experienced only a glancing blow.
 

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