What is a 'Fracture-Critical' Bridge?

"The bridge is fracture-critical. What that means is if a "member" fails, that would likely cause a portion of, or the entire bridge to collapse. There's no redundancy. The preferred method for building bridges today is that there is redundancy built in," Homendy said at a press conference on March 27, the day after the bridge collapse.

So, are fracture-critical bridges more suspectible to ship strikes? Shafer says no.

"In my personal opinion, I don't think the fact that this was a fracture critical bridge had anything to do with the collapse. It had everything to do with 110,000 ton vessel hitting a major support."

There are more than 17,000 fracture-critical bridges in the U.S., out of about 615,000 bridges total. Shafer says that number shouldn't worry you.

"The term fracture critical is really scary, right? You hear that word and you say, 'oh my gosh, that must be really bad.' We know a lot about these and we look at them differently. They are inspected on a much more frequent basis and maintenance is done in a different way such that any defects are addressed early and don't become a problem."