The infamous Doyle Drive built in 1936, and known as the most dangerous highway in the State of California, was redesigned in 2009 and re-named the Presidio Parkway. The shoring for the excavation of the new Southbound Battery Tunnel, a cut-and-cover tunnel that is 30 ft. to 40 ft below the original grade, was originally designed using 3 levels of struts. The General Contractor could see that this would impede the construction of the tunnel and hired PB&A to design a CRIP (Cost Reduction Incentive Proposal). PB&A used a creative design that employed one level of struts and one level of tiebacks. A very stringent deflection criteria was mandated due to the close proximity of the tunnel to the adjacent Veterans Administration Cemetery.
During Construction a Caltrans Official was heard to say, “The site is becoming quite impressive with the shoring walls now supporting a deep excavation. I think the CRIP redesign did save the contractor a lot time and hassle by not having to deal with multiple layers of struts and should facilitate the construction of the tunnel walls going back up.”