The investigative team has confirmed that workers were adjusting tension on the two tensioning rods located in the diagonal member at the north end of the span when the bridge collapsed. They had done this same work earlier at the south end, moved to the north side, and had adjusted one rod. They were working on the second rod when the span failed and collapsed. The road was not closed while this work was being performed.
The investigators have appointed a company to remove components that they believe warrant additional examination and testing. These components include sections of the floor, the canopy, a vertical member and a diagonal member; all from the north end of the structure in the area of where the failure occurred. In addition, they obtained additional core samples from this area to supplement samples obtained earlier.
The investigative team has obtained an exemplar tensioning rod and hydraulic unit used by the construction crew to make tension adjustments to the tensioning rods. .
The larger bridge components the investigative team is removing are being stored at a secured Florida Department of Transportation facility, under the control of the NTSB. Additional examinations and forensic deconstruction of these components will occur there.
Ongoing work includes:
- removal of the post-tensioning device to a temporary storage area and preparing it for shipment;
- preliminary comparison of bridge schematics to measurements obtained during the investigators’ examination of the collapsed structure;
- interviews with first responders.
“While segments of the bridge are being transported to and stored at an FDOT facility, there are no plans to reconstruct the bridge as part of the NTSB investigation into why the bridge collapsed,” said the NTSB. “The nature of the structure and the way it failed make reconstruction impractical.”
The next update on the progress of the investigation will likely be the preliminary report. Preliminary reports are generally completed within a few weeks following completion of field work. They do not contain analysis and do not address probable cause, said NTSB.