On March 15, 2018, 6 people were killed and 8 others were injured when an under construction pedestrian bridge collapsed in Florida. Several months later, the National Transportation Safety Board (NTSB) released their preliminary report while conducting an official investigation. The NTSB has recently released an “Investigative Update” to their preliminary report.
Since the preliminary report was released in May, the NTSB has conducted many additional tests, which are highlighted in the most recent report. The post-tensioning rods, post-tensioning jacks, and concrete around the failure points have all been analyzed and the report states that there weren’t any “notable material issues,” found up to this point.
Interviews have also been conducted with the majority of people and businesses the agency plans to talk to, but they did note that the remaining interviews are scheduled to be completed this month.
Perhaps the most significant information that was released in the report were pictures showing cracking around diagonal member 11. Vertical member 11 was in process of being re-tensioned when the collapse occurred. The bridges diagonal members were de-tensioned, per the plans, on March 10, 5 days prior to the collapse.
The preliminary report included several pictures, which were dated in February, of very small cracks near diagonal member 11. The pictures released in the latest report, dated March 13 (2 days before the collapse), show much more substantial cracking.
The NTSB’s investigation is still under way and the group has not yet determined the probably cause of the incident.