Cut and Cover Tunnel Construction at Sutter Health
The new Sutter Health Van Ness Geary Campus includes a pedestrian tunnel underneath Van Ness Avenue in San Francisco. Van Ness Avenue is designated as US 101, the main north-south route through San Francisco, crossing the Golden Gate Bridge. The tunnel will connect the hospital to the Medical Office Building located on the other side of Van Ness Avenue. The tunnel floor will be approximately 24 feet below Van Ness Avenue. Extensive advance work to locate and identify utilities was required, allowing design updates to accommodate these conditions before mobilizing for the critical path weekend street closure. Pile layout required design adjustments, mitigated with careful field verification of the conditions during construction.
Construction did require three 72-hour closures of Van Ness Avenue. Two closures were for installing the shoring and decking elements, and a final closure was for removing the temporary deck panels and restoring the roadway. Malcolm Drilling was the design-build shoring contractor for this cut-and-cover tunnel using soldier piles & lagging, cap beams, and precast deck panels. Seventeen utilities crossing the tunnel alignment were supported by the deck panels during the excavation process. All materials (concrete, rebar, formwork, etc.) for the tunnel had to be lowered into the hospital basement with the tower crane and then moved to the tunnel work location. Rapid-set concrete (similar to the type used for Caltrans concrete pavement repair) was batched on-site and used to restore the required concrete base section. A custom ventilation system developed for mining operations had to be used.
For all three closures, crews from Malcolm, McGuire & Hester (excavation and paving), and Herrero Boldt (traffic control and logistics) worked double shifts and finished all three closures ahead of schedule.