As demolition workers rushed Wednesday to remove a twisted and sagging 200 foot overpass beam from the U.S. 19 overpass in Clearwater, DOT engineers and contractors tried to solve the puzzle of what made it fail Tuesday when a pair of semi-tractor trailers rammed into the steel structure.
"We don't know," said DOT Spokeswoman Kris Carson. "That's the frustrating part."
Carson told 8 On Your Side the mishap investigation now centers on the demolition process since a biannual state bridge inspection only two months ago did not reveal any weaknesses in the structure.
Professional engineer Byron Evetts, who runs a firm called Existing Structures Engineering Inc in Cape Canaveral, told 8 On Your Side there are some obvious things that could have caused the 100-ton beam to deform during the removal process.
"That beam by itself, as long as it is would be inherently unstable," Evetts said.
8 On Your Side asked Evetts to review photos of the mishap and offer clues to what went wrong.
Evetts said once the road decking was removed from the State Road 60 overpass, the four steel support beams would have become vulnerable to something engineers call lateral buckling.
"You would rely on bracing, blocking, bridge deck, things like that to keep it stable," said Evetts.
Carson could not confirm whether demolition workers had taken measures to stabilize the beam before it twisted and sagged, but told 8 On Your Side the contractor did not deviate from the demolition plan approved by the DOT.
Whatever went wrong, Evetts told 8 On Your Side, the resulting mishap could have been far worse than minor damage to the two trucks that rammed the beam, and all of the subsequent traffic detours while workers remove the damaged beam and three others.
"When you have any kind of traffic and 100 tons of steel interfering with a roadway, it's a miracle somebody wasn't seriously injured or killed," said Evetts.