Award of Merit:
Caldecott Fourth Bore Eases Traffic — Beautifully
The Fourth Bore is notable for achieving its mission of easing traffic to and through the Caldecott tunnel complex, and for including advanced safety systems to keep motorists safe. (Photo: Karl Nielsen)
Student artist Aoife Gorshow poses with the medallion that she designed. (Photo: Karl Nielsen)
October 22, 2014
When it comes to star quality in an infrastructure project, the Caldecott Tunnel Fourth Bore has it all. Delivered on time and on budget? Check. Innovative construction techniques? Check. Careful traffic planning to avoid disruptions? Check. Stellar safety record? Check. An element of art? Check. Improved the lives of tens of thousands of travelers? Check.
This vital, two-thirds-of-a-mile link along State Route 24 through the hills separating Alameda and Contra Costa counties boasts all these qualities and more. The Caldecott Fourth Bore was completed in just four years thanks to an aggressive program of simultaneous tunneling from both ends, not only opening on schedule, but coming in within the $420 million budget.
Prior to the November 2013 opening of the Fourth Bore, crews needed to switch the direction of traffic in the morning and evening in the middle bore to accommodate the ebb and flow of commute traffic (and several times during the weekend as well). But even this intricate dance didn’t solve the monumental traffic that strangled the roadways to and through the tunnel complex.
With the advent of the Fourth Bore, Caltrans could dedicate two tunnels to westbound traffic and two to eastbound traffic — a move that proved to be the key to loosening the traffic knots. Since the opening of the Fourth Bore, the 160,000 motorists driving daily on State Route 24 have been experiencing up to 10 to 15 minutes of time savings in the reverse-commute direction.
The winning outcome made the construction challenges along the way well worth the effort. As they guided gargantuan, specially made drills deep into the mountainside through layers of prehistoric rock, the miners were in constant danger of releasing dangerous methane gas, and had to follow stringent protocols and wear special gear to ward off mishaps.
While crews braved the potential for methane along with unstable, crumbling rock deep inside the earth, a public relations team waged a vigorous outreach campaign on the outside to keep the public and the media informed.
“The Caldecott is built in an urban area, and as such, it was very important to have a very close relationship with the community,” said Caltrans Project Manager Cristina Ferraz. The project was a partnership effort with funding coming from a local sales tax administered by the Contra Costa Transportation Authority plus federal American Recovery and Reinvestment Act funds and regional bridge tolls from MTC. The Alameda County Transportation Commission also had an important role in delivering the project.
The new bore incorporates advanced safety systems, including 19 giant overhead jet fans to flush the tunnel’s air in the event of a fire. The third and fourth bores are linked by seven passageways to allow evacuations. The project also includes a new high-tech operations and maintenance command center that watches over all four tunnels.
Through a competition, six students from Alameda and Contra Costa counties were selected to design decorative medallions that echo the Art Deco medallions incorporated into the two original 1937 tunnels. Celebrating the natural beauty of the hillsides surrounding the Caldecott tunnel complex, the new medallions were unveiled to thunderous clapping at the opening ceremony for the Fourth Bore.
It was hard to tell who was prouder at the event: the beaming artists and their parents, or the officials, engineers and construction companies who had banded together to deliver this model infrastructure project that clearly deserves its Award of Merit.
— Brenda Kahn