On Thursday, March 15th of this year a pedestrian bridge weighing 950 tons of steel and concrete, still under construction, suffered a deadly collapse over a roadway outside of Miami. The disaster injured many and killed one construction worker and five civilians in cars stopped at a red light beneath the overpass. Engineering experts are speculating that this incident will be cited in the education of future structural engineers along with other historical structural engineering failures like the collapse of a pedestrian walkway at the Hyatt Regency Hotel in Kansas City, Missouri in 1981 fatally injuring 114 civilians.
With much to analyze, structural engineering experts from all over the world have weighed in to try and pinpoint the cause of this tragic accident. Without any of the preliminary construction plans which have yet to be released to the public, they are left scrutinizing any photo or video content of the aftermath in search of any indication of faulty design or construction. The National Transportation Safety Board is overseeing an investigation into the collapse, but until any official findings are released, which could take months, here are a few structural engineering expert hypotheses as to the cause of the collapse.
- One expert suggested in a YouTube video receiving over 600,000 views that a support rod located in the north diagonal truss was damaged during the one-day installation process, pushing it to a breaking point. The YouTuber hypothesizes that construction personnel were tightening rods in the trusses when the rod snapped, causing the collapse.
A related hypothesis suggests that, in response to some seemingly superficial cracking which had occurred in the concrete at the end of the bridge, engineers had decided to tighten the rods:
- Several well-respected engineers on an online forum have suggested that tightening the rods wouldn’t have made sense as the trusses were already under the substantial load of the bridge. In their expertise, they say it is more likely that crew members were loosening rods as planned which also could have led to the collapse.
- Those structural engineering experts examining photos of the aftermath suggest the strength of the joint located at the deck was inadequate, putting it under more strain than it could handle. Under these conditions, adjustment tension of the support rods could have pushed it over the edge, ultimately causing the collapse.
This is the sort of failure that strikes fear into the hearts of structural engineers everywhere — a fear that a simple overlooking of a literally fatal flaw within their work could cause a disaster like this one. Structural engineer experts all over the world are working to ensure that this kind of accident will never happen again.