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MIAMI (CBSMiami) – The National Transportation Safety Board provided an update into the early stages of their investigation into the deadly FIU pedestrian bridge collapse.

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NTSB Chairman Robert Sumwald addressed the media Friday evening.

He explained that there are seven other agencies and offices assisting NTSB with their investigation, which is focused on safety, the bridge design, construction, why the bridge collapsed and how something like this can be avoided in the future.

“We look at the emergency response,” Sumwald said. “We look at the roles and procedures of those organizations that responded to the event.”

Also, they will look into the overall emergency response, which is typical of any NTSB investigation.

Those agencies are the Federal Highway Administration, U.S. Department of Transportation, the Inspector General, OSHA, Miami-Dade Police, Florida Highway Patrol, FIU Police and Sweetwater Police.

They are expected to provide technical expertise to the investigation.

At around 6 p.m. on Friday an organizational meeting took place to designate the aforementioned assisting organizations.

Gallery: Scene of the FIU Bridge Collapse 

Sumwald provided information on what portion of the bridge was being worked on when it came down.

“The canopy, the top portion [of the bridge] and the walkway were integral parts of the structure that were connected by ten diagonal members,” he explained, pointing to a specific diagonal at the north end of the structure that crews were working on at the time of the collapse.

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“The construction crews were applying post-tensioning force that is designed to strengthen the diagonal member,” he said.

It is not yet known whether those tests are what caused the collapse.

Sumwald explained that recovery operation, which is run by local authorities, takes precedence but it hasn’t impeded NTSB’s investigation.

He said that the goal is to obtain as much “perishable evidence” while they can, as the bridge would no longer be on the scene in a couple days.

Robert Accetta, who is the investigator in charge of the NTSB’s investigation, was asked about reports of cracks in the bridge before the collapse.

Those reports were confirmed by the Florida Department of Transportation in a press release.

“A crack in the bridge does not necessarily mean that it’s unsafe,” Accetta said. “I know the crews were out there inspecting it and they were applying tension to strengthen a member. I don’t know if that was related to the cracks that they discovered. It’s still too early in the investigation for us to determine.”

Sumwald said he expects his team to be in South Florida for 5-to-7 days.

“Once our team leaves here, that’s really just the beginning of the investigation because there’s a lot of work that goes into this,” Sumwald said. “This will be a very complicated and very extensive investigation.”

Another big question which will need to be answered is why, if the bridge was still under construction, were cars allowed to travel underneath it.

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“We want to look at how the contractors identified risk and mitigated those risks associated with the construction of this bridge,” Sumwald explained, saying he knew they shut down all traffic when the bridge was installed on Saturday. “We want to understand what those decisions were and why they were made.”