The new Sutter Health Van Ness Geary Campus includes a pedestrian tunnel underneath Van Ness Avenue in San Francisco. Van Ness Avenue is designated US 101 – the main north south route through San Francisco over 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 prior to mobilizing for critical path weekend street closure. Pile layout required design adjustments to mitigate with careful field verification of the conditions during construction.
Construction did require three 72 hour closures of Van Ness Avenue. Two closures to install the shoring and decking elements and a final closure to remove the temporary deck panels and to restore the roadway. Malcolm Drilling was the design build shoring contractor for this “cut and cover” tunnel using soldier pile & lagging, cap beams and precast deck panels. Seventeen utilities running across the tunnel alignment were supported from 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 for Malcolm, McGuire & Hester (excavation and paving) and Herrero Boldt (traffic control and logistics) worked double shifts and finished all 3 three closure ahead of schedule.