The extension & raising of FLL runway 9R - 27L has runway and taxiway bridges being built over the FEC & US-1. Evidently one of the 120 ft long pre tensioned concrete beams collapsed and took out 5 or 6 more that all fell on FEC tracks. One construction worker very slightly injured. This report is very brief.
Thank goodness no FEC train came upon these beams. Wonder if the impact on tracks and ROW will cause new rails to be needed and surfacing also needed.
ATL airport has much the same bridging for the new southern most runway running over I-285. There are s many beams very close together spanning I-285.
One has to wonder what caused this collaspe whether structural or otherwise. As a pilot it certainly would worry me landing on that section with the instantenous impact forces unless a full explanation is forth coming… Probably the most accurate report will come from Aviation Week. If anyone can access a report from Aviation Week please forward it to us.
This extension and raising of the runway is the reason for FEC’s extra siding at the construction site to short hauling the necessary fill for the rebuilt runway.
http://www.sun-sentinel.com/news/broward/fort-lauderdale/fl-structure-collapse-airport-20131102,0,2409694.story
From this article - a quote mentions the beams “rolling” - I suspect that they tipped over sideways in succession:
http://www.wsvn.com/news/articles/local/21012112635766/5-concrete-beams-collapse-at-fll/
The ‘steps’ down of the multiple beam bearings at the abutment wall seem to be pretty steep, and I could see where a beam tipping over would drop down and hit the next one at the top pretty hard, causing it to fall over too . . .
Blue Streak,
When finished, the bridge will be more than capable of handling a 747 " heavy" landing on it. I can’t quote the maximum landing weight for one but it is over 500,000 pounds.
I’m certain the investigation will reveal that someone forgot to secure one of the beams when it was set in place. In other words, a simple construction accident.
After a little further thought, I wonder if this was caused by a lack of lateral bracing - one example is the short (typ. 18" long or so) X-shaped wood or metal straps that are sometimes visible between the floor joists above your basement. On bridges, sometimes they’re much larger and heavier, and are called diaphragms.
Alternatively, without a deck in place on top yet - the portion of the beam that’s usually in compression - perhaps these beams were unable to resist the bending and deflection downwards caused by their own weight, and simply buckled down and then out to the side to relieve that stress.
The maximum landing weight of a 747-8F, the freighter version of the current in-production 747-8 series, is 757,000 lb (343,000 kg).
Until all permanent blocking, bracing and securements are in place - any and every construction project has less than the required stability and as such can relatively easily collapse if something unforseen happens. Generally with catastrophic results and loss of life.