|Katrina triggered Miami-area bridge colloapse.|
Miami-Dade County officials have asked a projects designer, construction manager and a third party to investigate the Aug. 25 Hurricane Katrina-related collapse of two spans of an overpass under construction in suburban Miami, Fla. Thirty-two unbraced, prestressed concrete girders fell from the bridge onto State Road 836, the Dolphin Expressway, and a nearby grassy area.
County officials claim that prior to the hurricane they repeatedly urged the contractor, Miami-based DeMoya Group, to install lateral bracing but the contractor failed to act before it was too late.
Managers of the DeMoya Group could not be reached for comment on the allegations. An official of the construction manager and inspection consultant, Bolton Perez & Associates, Miami, declined to comment.
Florida Dept. of Transportation engineers inspected the collapse site Aug. 26 and found that DeMoya Group had not installed lateral bracing, claims William B. Nickas, FDOT state structures design engineer. FDOT engineers say they did not find ground instability.
Contractors are responsible for temporary works, Nickas says. Six-ft-deep, 142-ft-long concrete beams had been erected atop piers on most of the four-lane bridge.
"Its not like a complete bridge collapse," says Rick Crooks, president of project structural engineer EAC Consulting Inc., Miami. "The structural system was not fully in place as yet. What contractors typically do until they have everything poured or done is brace or shore."
EAC representatives were not on site observing the bridges construction, says Crooks.
County specifications meet FDOT standards, which require adequate brace products to resist wind forces. "The spans had been erected for some time and the contractor had started doing diaphragms but for some reason didnt continue," claims Ovidio Rodriguez, the countys assistant director of public works. By the time county officials realized Katrina was bearing down on the site it was too late.
Workers from DeMoya Group did clear tons of rubble from SR 836 in time for the road to reopen by the evening of Aug. 26, says a spokesman for the Miami-Dade Expressway Authority.
(Photo courtesy of Miami-Dade Expressway Authority)
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