Construction crews will officially begin the drilling process of the Caldecott Tunnel’s fourth bore in Orinda Monday morning. The first drill will happen during a commencement event to celebrate the occasion.
The fourth bore will be drilled using a boring machine called a “Road Header.” The machine is over 50 feet long and weighs 130 tons. Needless to say, you’ll likely notice it on your way into the tunnel.
While the drilling is starting on the Orinda side, it will eventually start on the other side of the hill as well. Because of the softness of the rock that crews will be drilling into, they will only be able to drill 10 feet per day, as they will have to stop every three feet to reset support.