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...

Sure, precautions might not work as well as intended.

But my comment was in regards to having to build a really expensive bridge to make it crash resistant. I pointed out that you can instead build a cheap flimsy bridge and put the protection in the water around the pylons.

My impression is that the Baltimore bridge had no such extra protection (?) In that case, it's not really "the best design", right?

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.

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.

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.

"Failed" isn't the binary you're trying to make it.

Yes, the towers failed to survive serious damage. But the 40,000 more deaths would have been "socioeconomic trouble", in spades. Even by your own chosen measure, the survival for an hour was a partial success.