Cracks found on FIU pedestrian bridge weeks before collapse, report shows

MIAMI — A key concrete support truss in the doomed Florida International University pedestrian bridge developed worrisome cracks 10 days before the structure was lifted into place over the Tamiami Trail, photographs and an internal email unintentionally released by the school show.

The documents, released in response to public records requests from the Miami Herald, show that FIU’s construction and engineering team discovered potentially problematic cracks in the bridge earlier than officials have previously acknowledged.

The cracks were found in late February at the base of a diagonal support member at the north end of the span. Independent engineers have identified that as the point where the structure shattered on March 15 while under construction, sending the 950-ton bridge crashing onto the roadway below and claiming six lives.

Three independent engineers who examined the photos, records and bridge blueprints at the Herald’s request concurred that the cracks were a red flag signaling potentially critical structural problems. Outside experts have zeroed in on that truss member, Cracks were discovered in the Florida International University bridge 10 days before it was raised into the air above busy Tamiami Trail. The bridge collapsed on March 15. identified in plans as No. 11, as being “underdesigned” — that is, not strong enough to withstand the pressure from the weight of the bridge it was supposed to hold up.

The location and diagonal shape of the cracks shown in the FIU team’s photos support that theory, the engineers said. They said the cracks should have prompted work on the bridge to stop for an in-depth review that likely would have resulted in the truss connection being re-engineered and significantly reinforced.

“Knowing the stresses that member was under and what happened, that crack was something that in hindsight should have been investigated,” said David Beck, a New Hampshire engineer who helped uncover mistakes in Boston’s $10.8 billion Big Dig project.

Linwood Howell, who runs a Texas engineering firm that specializes in bridge design and inspection, said the cracks were signs of the structure’s “imminent failure.”

“There’s nothing they could have done short of starting over and redesigning the structure,” Howell said.

A third engineer consulted by the Herald concurred with the first two but asked not to be named.

A fourth bridge engineer, Ralph Verrastro of Naples, said the cracks did not appear significant to him.

“The photos don’t clearly provide any clues to me related to ultimate failure,” Verrastro said in an email. “I would assume these cracks would have been repaired by epoxy injection before the bridge was moved.”