This, 100%. I forget the specific numbers but regardless, the kinetic energy of a thing with that much mass, even moving at a very slow speed, is off the charts. Designing a bridge or protections for a bridge to survive that would at a minimum be cost prohibitive, if even possible with today’s materials and construction technologies.
> The NTSB found that the Key Bridge, which collapsed after being struck by the containership Dali on March 26, 2024, was almost 30 times above the acceptable risk threshold for critical or essential bridges, according to guidance established by the American Association of State Highway and Transportation Officials, or AASHTO.
> Over the last year, the NTSB identified 68 bridges that were designed before the AASHTO guidance was established — like the Key Bridge — that do not have a current vulnerability assessment. The recommendations are issued to bridge owners to calculate the annual frequency of collapse for their bridges using AASHTO’s Method II calculation.
Energy doesn't mean squat without a time component over which it's dissipated.
Stopping a car normally vs crashing a car. Skydiving with a parachute vs skydiving without a parachute.
For something like ship vs bridge you have to account for the crunch factor. USS Iowa going the same speed probably would've hit way harder despite having ~1/3 the tonnage.
Plan the bridge so any ship big enough to hurt it grounds before it gets that close. Don't put pilings in the channel. It's just money. But it's a lot of money so sometimes it's better to just have shipping not suck.
Alternatively, the Chunnel will almost certainly never get hit with a ship.
capyba|3 months ago
sitkack|3 months ago
> The NTSB found that the Key Bridge, which collapsed after being struck by the containership Dali on March 26, 2024, was almost 30 times above the acceptable risk threshold for critical or essential bridges, according to guidance established by the American Association of State Highway and Transportation Officials, or AASHTO.
> Over the last year, the NTSB identified 68 bridges that were designed before the AASHTO guidance was established — like the Key Bridge — that do not have a current vulnerability assessment. The recommendations are issued to bridge owners to calculate the annual frequency of collapse for their bridges using AASHTO’s Method II calculation.
Letters to the 30 bridge owners and their responses https://data.ntsb.gov/carol-main-public/sr-details/H-25-003
potato3732842|3 months ago
Stopping a car normally vs crashing a car. Skydiving with a parachute vs skydiving without a parachute.
For something like ship vs bridge you have to account for the crunch factor. USS Iowa going the same speed probably would've hit way harder despite having ~1/3 the tonnage.
potato3732842|3 months ago
Plan the bridge so any ship big enough to hurt it grounds before it gets that close. Don't put pilings in the channel. It's just money. But it's a lot of money so sometimes it's better to just have shipping not suck.
Alternatively, the Chunnel will almost certainly never get hit with a ship.
jacquesm|3 months ago
Have a look at the trajectory chart that I posted upthread and tell me how in this particular case you would have arranged that.