Federal inspectors Thursday released images showing cracks in the concrete of a pedestrian bridge -- larger than what had been seen before -- on the campus of Miami's Florida International University days before it collapsed and killed six people.
The photos were released by the National Transportation Safety Board (NTSB) as part of another preliminary report in the investigation of the March 15 collapse.
The agency previously released photos taken on Feb. 24, documenting small cracks at the ends of the bridge. The new photos featuring larger cracks were taken after March 10, when the prefabricated bridge was transported from a casting yard and set into place on permanent piers.
Investigators interviewed employees from eight companies involved in the bridge's design and construction, the report said. Experts have also tested concrete, steel rods and a hydraulic jack. The report didn't include any test results or conclusions about what might have caused the collapse.
The bridge was to span a busy highway and canal and connect FIU's campus to the neighboring community of Sweetwater. Five people in vehicles and a bridge worker were killed in the collapse; eight other people were hurt.
The bridge had been highlighted by FIU officials as an achievement for an accelerated construction method that was supposed to reduce risks to workers and pedestrians and minimize traffic disruption.
When the bridge fell, construction was behind schedule and millions over budget, in part because of a key change in the design and placement of one of the span's supports, public documents showed.
The Associated Press contributed to this report.