Federal officials will lead bridge investigation

NTSB chair Rosenker
NTSB chair Mark Rosenker, bottom, says investigators will try to reassemble the section of the I-35W bridge that collapsed and fell into the Mississippi River. The NTSB will be heading the investigation into the cause of Wednesday's I-35W bridge collapse.
MPR Photo/Jeff Horwich

Thursday morning NTSB chair Mark Rosenker cautioned that it might take a year or more to pinpoint the cause of the bridge collapse. He said part of the investigation involves the salvaging of the broken concrete and steel bridge debris from the river and reassembling it. But he says now the NTSB won't have to completely reconstruct the bridge to find out why it fell.

"I am optimistic that we can do this a lot faster today -- than I was earlier this morning when I didn't know we had this failure analysis program."

The failure analysis program created by an employee of the Federal Highway Administration. Rosenker refused to name the employee but says the man developed it as part of his PhD program at the University of Minnesota.

He says the program will create a digital image of the bridge structure based on data from inspection reports, eye witness accounts and a piece of video taken of the collapse from a nearby security camera. Rosenker says they will be able to take away virtual structural pieces of the bridge until it falls down.

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"When we do this through the computer model. It will speed up the process of understanding which one of the components -- which one of the elements failed. And that's going to help us a great deal. That probably this program, along with the video, is going to probably improve the ability of the NTSB to get the facts, and do its analysis by months."

Rosenker says the first part of the investigation is the 'documentation phase.' A 19 member team of investigators are gathering crucial documents, such as inspection reports on the bridge, eyewitness accounts and photos. The team members are experts in different areas such as bridge and highway engineering. Rosenker says investigators will study every bit of evidence very closely.

"I can assure that we will be looking at every single document we can get our hands on. If we need to issue a federal subpoena, I will sign one. We will get what we need in order to understand what happened here. I'm confident of that."

The NTSB has investigated several significant bridge disasters in the last 24 years. In 1983, an interstate bridge in Connecticut fell and killed three people. In 2002, 14 people died when a barge hit a bridge pier in Oklahoma causing a 500-ft section of bridge to collapse.

The NTSB is asking anyone with eyewitness accounts or photos of the collapse to call them at 866-328-6347.