Caldecott Tunnel fourth bore nears completion


1937 was a very big year for Bay Area transportation. It's when the Golden Gate Bridge and the first two Caldecott Tunnels opened. 2013 is going to be a much bigger year; one for the record books. First we have the opening of the Devil's Slide Tunnel, then the opening of the new Bay Bridge, followed by the opening of the Caldecott Tunnel's fourth bore.

There will be plenty of high tech features in the Caldecott's new fourth bore, but Wednesday, elbow grease and shovels were still the preferred method for work on a groundwater drainage system.

At the same time, work has just begun on one major milestone, which is putting in the roadway. Eventually layers of materials, capped with pavement, will fill 2-3 feet from where the surface is now, reaching to the shoulder curb on one side and to just below the pedestrian walkway on the other.

When finished, the fourth bore will carry west-bound traffic only. "With the construction of the fourth bore there will be two tunnels permanently dedicated to east-bound traffic, two tunnels permanently dedicated to west-bound traffic that will eliminate the twice a day traffic shifts and the pop-ups," said Ivy Morrison, a Caltrans spokesperson.

The fourth bore has a number of safety features, including 19 200-horsepower jet fans yet to be hung from above. They'll help in firefighting and air quality. "They can actually reverse the direction of airflow. Some of the 19 jet fans can direct air in one direction and the other set can direct air in the opposite direction, just depending on where the fire is and what the air quality issues are in the tunnel," Morrison said.

There will be seven pedestrian cross-overs with electronic motion sensor doors. There will be a PA system and security cameras. Much of the work to complete the tunnel will be the sophisticated, behind the scenes systems. "The installation of the ventilation systems and the fire systems and the air quality monitoring systems, that not only need to be installed, but they need to be integrated with the existing systems and with the new operations and maintenance building and also tested before the tunnel can open to traffic," Morrison said.

The new tunnel is on track to come in on budget, which is $402.1 million.

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