Breakthrough of the Caldecott Tunnel’s Fourth Bore Marks a Major Project Milestone

The proverbial light at the end of the tunnel became a reality this week when a giant road header chewed through the last few feet of rock blocking access between the east and west sides of the Caldecott Tunnel Fourth Bore. The breakthrough of the upper level of the tunneling project occurred with little fanfare at around 2:40 p.m. yesterday. Sponsors saved the celebration for today, gathering at the west portal of the new bore to mark the important milestone and show off progress to the media.

“Our celebration is after the fact to avoid disrupting the project’s schedule,” said Caltrans District 4 Director Bijan Sartipi, who also serves as an MTC commissioner and acted as MC for the press conference.

The excavation started in August 2010 in Orinda on the east side of the new bore; some seven months later, excavation started from the west side in Oakland. The project has been on the fast track, with crews working around the clock in a race to meet deep inside in the 3,248-foot-long tunnel.

“It has taken about a year to break through the top half of this tunnel, but it took many years of planning to see the construction begin on this badly needed congestion-relief project,” Sartipi said.

Sartipi credited significant federal American Reinvestment and Recovery Act funding with finally bringing the project to fruition, along with local and regional funding sources. More than a congestion relief project, the Fourth Bore represents infrastructure investment that can create jobs and stimulate the economy, he said.

“Today we want to emphasize to all Californians and the entire nation the importance of continuing to invest in America’s infrastructure,” Sartipi said, adding that the bulk of California's ’ transportation facilities were built in the 1970s and will require more than $70 billion over the next 10 years for maintenance, rehabilitation and operation.

Officials struggled to be heard above the hum of adjacent traffic and ongoing construction activities at the site, a condition that one speaker saw as a good omen. “That’s not just the sound of progress, that’s the sound of jobs, good American jobs,” said Brian Hooker, speaking on behalf of U.S. Representative John Garamendi (D-Walnut Creek).

Also on the speaker line-up were MTC Vice Chair Amy Rein Worth, an Orinda councilwoman, and MTC Commissioner Mark Green, who also serves as president of the Association of Bay Area Governments and mayor of Union City.

“This tunnel has been a dream for the East Bay for nearly 40 years,” Worth said. “Back in 1936 when the first two modern tunnel bores were built only 80,000 people lived in Contra Costa and most of them lived west of the tunnel. Today, Contra Costa is home to over a million residents, and achieving the reality of this dream is long overdue.”

The bulk of the tunneling occurred from the east side, with the breakthrough occurring about 640 feet in from the west portal, according to Ivan Ramirez, Caltrans senior engineer for the Caldecott project. The last stretch was tricky due to very fractured rock that had a tendency to crumble. “We had to watch the walls carefully,” Ramirez said. “The rock tried to beat us, but we beat it back.”

For most of the tunnel’s length, only the top level has been excavated. Workers will now take a second pass through the bore to dig out the lower level and to install a permanent, sturdier lining, a process that will take about six months, according to Ramirez.

The new Fourth Bore will relieve congestion in the off-peak direction by permanently dedicating two bores to westbound traffic and two to eastbound traffic. This will eliminate the need to reverse the traffic direction in the center bore twice a day to accommodate morning and evening commute traffic.

The $391 million Fourth Bore project is primarily funded ($180 million) through the American Recovery and Reinvestment Act (ARRA) of 2009; at the time of the grant award, it was the single largest stimulus project in the nation. Additional funding came from a local transportation sales tax (Measure J) passed by Contra Costa voters in 2004; and from Regional Measure 2 bridge toll funding distributed by MTC.

The Caldecott Fourth Bore Project is a partnership between the Federal Highway Administration, Caltrans, MTC, the Contra Costa Transportation Authority and the Alameda County Transportation Commission. 

—Brenda Kahn