Defects Found in Freeway Bridge

Construction defects may delay the opening -- and possibly require the rebuilding -- of a $12-million carpool lane connector at the busy interchange of the San Diego and Costa Mesa freeways.

Orange County transportation officials said Tuesday that they are investigating structural defects recently discovered in portions of the two-way, half-mile ramp between the freeways.

Although experts said the bridge is in no danger of collapsing, patches of broken-off concrete raise questions about the connector’s ability to carry heavy traffic.

Repair work could involve as little as redoing sections of concrete or, in the worst case, rebuilding the 60-foot-high flyover at a cost of millions of dollars and a delay of eight months.

The ramp near John Wayne Airport was scheduled to open in April.

But officials said the defects could postpone that until the end of next year, at the latest.

“We are now assessing what the problems are and how to fix them,” said Rick Grebner, an engineer and project manager for the Orange County Transportation Authority. “If left as it is, it won’t carry the traffic it was designed for. There is a problem of long-term durability.”

The carpool connector between the 405 and 55 is part of a $125-million project to relieve congestion on one of the nation’s busiest highway interchanges. Drivers make about 433,000 trips a day through the area.

OCTA is funding the project through Measure M, the local sales tax used for transportation projects. Caltrans is overseeing construction of an array of connectors and offramps, including ones at Bristol Street and Avenue of the Arts in Costa Mesa.

The entire project, which is being built by C.C. Myers Inc. of Rancho Cordova, Calif., is scheduled to be finished in 2004, about five years after construction began.

Pam Gorniak, a spokeswoman for the California Department of Transportation, said Tuesday that it was premature for the agency to issue any statements about the cause of the problems or who was responsible. A complete assessment is due in about two months.

“Everything is speculation at this point,” Gorniak said. “We need more data on this. There is nothing conclusive yet.”

Work was halted on the connector about two months ago when construction crews found that surface layers of concrete were falling off supporting walls under the roadway. The unusual condition is known as spawling.

So far, the investigation has found that spawling has affected about 5% of the concrete that covers the bridge’s reinforcing steel along the walls of the road’s inside curve.

Although the assessment is not finished, Grebner said the concrete might have fallen off when construction crews, using hydraulic machinery, applied tension to reinforcing cables that run through the ramp.

The tension, designed to strengthen the structure, could have caused the cables to move unexpectedly, popping off the concrete.

“The bridge is not moving or creeping,” Grebner said. “No new damage has been found, but the study is still underway.”

OCTA officials said the bridge is seismically safe, but traffic will not be allowed on it until the structure is declared sound. The problems, they added, will not affect other parts of the interchange project.

“What they are trying to do is very appropriate,” said Masanobu Shinozuka, chairman of UC Irvine’s department of civil and environmental engineering. “Everyone concerned is involved, and they are not trying to hide anything. This is good.”

Shinozuka said spawling is an unusual condition that can be caused by a variety of factors, including design, poor quality control and environmental conditions such as heat or cold.

Grebner said investigators are looking into whether the tight curve of the connector had anything to do with the failing concrete.

How much the repairs will cost is still unknown, Grebner said. If there are construction-related problems, for example, Caltrans or the construction company might be responsible for additional expenses.