The Bus Ramps Project connects the state of the art transit facility to the Bay Bridge via an elevated bridge structure above several of San Francisco’s main commute thoroughfares as well as access to the Bus Storage Facility. The Bus Ramp Bridge project consists of a section of concrete box girder viaduct that connects to the Bay Bridge, a signature cable stayed bridge span and a section of steel beam girder with concrete deck span. The purpose of the project is to reduce congestion and to minimize travel times by keeping buses of the city streets. From I-80, buses will travel over an on-grade section, cross over Harrison Street on bridges supported by abutments, travel down a 450’ long section of road supported by mechanically stabilized earth (MSE) and cross over several San Francisco Streets on a 700’ long box girder viaduct before crossing over Howard Street on the cable stayed bridge. The final 50’ connecting the cable stayed bridge to the Transit Center is the structural steel span.
Shimmick overcame many challenges that required innovative techniques to accomplish the build out of the Transbay Bus Ramps Bridge. The most critical and challenging portion of the Bus ramps project was installing and removing falsework over Howard Street and over the Transbay Terminal building. The work required constant coordination with the other project operations that were happening above, adjacent, and below the Bus Ramp Project.
Additionally, the very limited staging areas for the CIDH Pile and Barrette Pile subcontractors meant innovative and highly detailed plans were required to perform the work. Shimmick crews installed slurry lines across several City blocks and under multiple streets to allow pumping of drill slurry from the subcontractor’s slurry tanks to the pile locations. The heavy drill rigs required to drill the 180’x20’x5’ Barrette Piles for the cable stay bridge pylon foundation needed to be within 20 feet of the Transbay Terminal excavation (60 deep excavation). Due to the load restrictions on the shoring wall, Shimmick designed a work platform using crane mats. This simple crane mat system reduced the load on the shoring wall and eliminated the requirement for an extensive trestle to stage the drilling equipment.
Shimmick value engineered the Frame 5 drop in span from orthotropic box girders to cambered steel girders to significantly reduce the project cost of the first cable stay bridge for vehicular traffic in California.
AGC Constructor Award – Finalist for Meeting the Challenge of a Difficult Job.