Federal, state and local officials gathered in Orinda Friday to celebrate the beginning of construction on the fourth bore of the Caldecott Tunnel.

Rep. John Garamendi, D-Walnut Creek, joined members of the U.S. Department of Transportation, the state Legislature, Caltrans, and local transportation agencies at the groundbreaking ceremony for the project that will add a fourth bore to the tunnel connecting Oakland and Contra Costa County via state Highway 24.

The four-year project, which costs $420 million, will alleviate traffic congestion in the area and is expected to create jobs for more than 5,000 construction workers.

John Porcari, deputy secretary of the U.S. Department of Transportation, said the money "is being invested in more than just a tunnel."

The project represents "investing in jobs, here and now today, when we need them," Porcari said. "We're investing in an easier, safer, and less congested trip for the 160,000 daily commuters when this project is finished, and by reducing congestion here in the East Bay, we're investing in a greener environment."

Nearly half the project is being funded by money from the American Recovery and Reinvestment Act of 2009. The $197.5 million in federal stimulus money is an example of how "the federal government was there when we needed it, Garamendi said.

The two-lane, 3,389-foot bore is expected to be finished in spring 2014 and will eliminate the need for the existing central bore to alternate between westbound and eastbound traffic for the morning and evening rush hour.

Garamendi, who lives in Walnut Grove, had his office in San Francisco during his eight years as the state's insurance commissioner and lieutenant governor, and said he traveled through the Caldecott Tunnel nearly every day.

The construction of the tunnel, being done by the Sylmar-based firm Tutor-Saliba, will begin with crews setting up their staging areas and building a temporary sound wall at the west portal. Crews will be working from both sides of the tunnel, excavating at a rate of one to two yards per day.

— Bay City News Service

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