Freeway Bridge Tab Cut Again

First there was talk that a damaged carpool bridge on the San Diego-Costa Mesa freeway interchange would have to be torn down. Two months later, engineers thought the half-mile span could be spared the wrecking ball by making up to $5 million in repairs.

Now, the Orange County Transportation Authority estimates that the $12-million carpool connector in Costa Mesa can be fixed for $1.5 million to $2.5 million.

“We’ve had a chance to design the repairs and refine our cost estimates,” said Rick Grebner, a senior project manager for OCTA.

The 60-foot-high connector is part of a $125-million effort to improve the interchange, one of the nation’s 10 busiest. Drivers make about 433,000 trips a day through the area. The entire project, underway for about four years, is scheduled to be opened by the end of the year.

Last summer, the outlook for the carpool bridge didn’t look so promising. Work had come to a halt in August after cracks and failing concrete were discovered along the interior girders that support two of the bridge’s three sections.

Engineers suspect several factors led to the damage, including irregularly spaced steel reinforcing bars, thin concrete and too much tension on supporting cables through the concrete girders. Caltrans’ design standards are also at issue.

Engineers initially feared that much of the connector would have to be ripped out and rebuilt at a cost of more than $8 million -- at least three-quarters of the structure’s original cost. The opening date for the bridge, scheduled this month, was pushed back.

After months of investigation and discussion, OCTA announced in January that the bridge would not have to be demolished. Authority officials said that $3 million to $5 million in repairs would restore the span.

The costs were revised downward again this week as the repair plans began to take shape. The design calls for steel reinforcements and layers of concrete along the interior and exterior of the structure. The reinforcements include more rebar and giant U-shaped bolts to secure bundles of supporting cables in the span’s concrete girders.

If all goes well, the two-way bridge, along with the rest of the interchange, will open at the end of the year.

“I’m glad this is not as serious as we all thought and the bridge can be fixed at a reasonable cost,” said Cypress City Councilman Tim Keenan, chairman of the OCTA board of directors. “Hopefully, this can be covered without any additional taxpayer expense.”

Grebner credited some of the cost savings to Freider Seible, a bridge expert and dean of UC San Diego’s engineering department. Seible was hired by OCTA to evaluate the structure and recommend repairs.

Still to be decided are the government agencies and private contractors responsible for the repair costs. Grebner said mediation sessions will be held in the months ahead.

Caltrans is administering the project, while OCTA is paying for the interchange improvements. Jacobs Engineering inspected the bridge work on behalf of OCTA. The designer is CH2M Hill, an international engineering firm, and the main contractor is C.C. Myers Inc. of Rancho Cordova.