Friday marks the end of a mandatory 55 day waiting period after Caltrans awarded the construction project to a Sylmar- based construction firm.
The Caldecott Tunnel connects Oakland to Contra Costa County via Highway 24.
Adding a new, two-lane fourth tunnel will eliminate the need for one of the existing tunnels to alternate between westbound and eastbound traffic for the morning and evening rush hour.
The project is expected to cost $420 million and be completed in 2013.
