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Report Coming Soon On Why Chunks Fell From Bridge

News Channel 8 photo by WALLY PATANOW

Consultants say the bridge is safe, despite the loss of concrete.

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By MARK  DOUGLAS | News Channel 8

Published: March 12, 2009

BELLEAIR SHORES - Pinellas County public works engineers expect a preliminary report as early as today on why 2,700 pounds of concrete chunks rained down from the new Belleair Causeway Bridge during a construction mishap February 6

Bridge workers were stretching or "post-tensioning" one of the 22 "tendons" that hold concrete roadbed segments together like beads on a string, consulting engineer James Phillips III of ECDriver said at the time of the accident.

Phillips said a kink in the steel tendon imbedded in the concrete straightened out and pushed out chunks of concrete beneath it.

The mishap left a shallow hole about 8 feet square in the bottom side of the bridge's eastern approach, exposing the steel tendon and other steel reinforcement used to strengthen the concrete structure.

"It does not impact the overall strength of the bridge so it still has the full ability to carry loads," Phillips said.

He said he doesn't believe anything will stand in the way of opening the new span to traffic by the end of April.

"There's a tremendous amount of work to be done but right now the contractor says they're on schedule to get this bridge open," Phillips said.

Pinellas County holds the general contractor, Johnson Brothers Inc., responsible for repairing the problem and paying any associated costs. Pinellas County is building the $72 million bridge over Clearwater Harbor with federal money and "Penny for Pinellas" tax dollars.

The county hired the concrete consulting firm E & L Support Services Inc. to review the problem. E & L technicians discovered a number of microcracks in the bridge segment, each about as wide as the ball point on the end of a pen.

"This was the first segment of the bridge that was cast and we believe that the microcracking is only about three-quarters of an inch into the structure so we don't think it's going to have an effect on durability and it certainly doesn't affect the strength," Phillips said.

E & L said in a report that the concrete "is of good quality" but raised questions about the source of microcracking in samples taken from both the top and bottom of the bridge.

"The microcracks do not appear to significantly compromise overall integrity of the concrete" but the report also noted the sample taken from the bottom of the bridge "tends to locally split along microcracks when hit with a hammer in the laboratory."

The report concludes "further field and laboratory tests would be needed to determine exact causes and significance of these microcracks."

A more immediate problem is the large gash left under the bridge after the kinked tendon sent hundreds of chunks of concrete crashing to the ground below.

Bridge workers are using jackhammers to carve out a hole twice as large as the original 8' by 8' area so they can attach a patch.

"We're in a fairly corrosive salt water environment and that concrete layer underneath is what protects the steel from rapidly corroding," Philips said. "So it's very important that we put it back and put it back so that it has real integrity to it as an integral part of the overall structure."

Before that happens, an outside engineering consultant, Bridge Concepts Inc. will have to complete an investigation of the tendon mishap and state engineers will have to approve the repair process. A preliminary version was expected to be finished as early as today, county spokeswoman Meg Korakis said.

Editor's Note: An earlier version of this story included an incorrect date for the construction mishap.

Mark Douglas can be reached at (727) 536-9603 or mdouglas@wfla.com

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