The New East Span of the San Francisco-Oakland Bay Bridge (SFOBB) replaced the 70-year-old steel truss structure, a portion of which had collapsed during the 1989 Loma Prieta Earthquake. The new bridge is divided into (1) the Yerba Buena Island (YBI) transition structure, (2) Self-Anchored Suspension (SAS) bridge, (3) Skyway structure viaduct, and (4) Oakland approach structure (OTD). It was opened on the Labor day of 2013.

EMI in a joint venture with Fugro West were the geotechnical engineer of record for the entire bay bridge from 1998 to 2014. EMI assembled a project group consisting of well renowned seismologists, geologists, and geotechnical engineers to perform the required engineering support and complete the highly complex foundation designs. All work was under peer review.

Investigations
Fugro-EMI conducted large-scale geotechnical soil and rock explorations overwater and on land at the YBI and OTD approaches. Land-based investigations involved highly variable terrain, difficult access, environmental issues and working with multiple agencies. Challenges included highly variable ground conditions including hard rock, soft compressible soils, steep soil slopes/landslides, and buried rock dikes. Rock is exposed at YBI and several hundred feet deep at the Oakland Touchdown.
On YBI, EMI led a study of controlled blasting in rock to develop project specifications for large excavation on YBI to construct the West Pier of the SAS structure.

Geotechnical Engieering Design
Design challenges included high seismicity, hard rock and soft bay mud soils, soil and rock slope stability, constructibility, and lateral ground spreading. A part of the signature SAS structure is founded in rock while another portion is founded in soft bay mud. This led to complex dynamic design problems arising from distinctly different foundation stiffness during seismic excitation. 
EMI employed state-of-the-art site-response and kinematic soil-pile interaction analyses to establish multiple-support ground motions for foundation designs in conjunction with foundation springs modelling the seismic response of the soil-pile foundation systems.
Bridge foundations included driven steel piles including pipe piles up to about 7-ft diameter, cast-in-drilled hole piles up to 8-ft diameter, spread footings on soil and rock with tiedowns, and a large hybrid pilecap supported on a grid of large-diametere drilled shaft piles and bearing on rock at one end. At the OTD, EMI supported Caltrans in design and construction of ground improvement using wick drains and lightweight concrete approach fill.

Construction
During construction, EMI provided geotechnical support to complex foundation construction at both approaches for many years. Support included contractor submittal reviews, pile driving monitoring, field inspection, and supplemental investigations. Support included design of temporary construction measures such as major 5-level and 17-level tieback walls, geogrid-reinforce steep slope restorations, booths. EMI participated in the Caltrans Contractor Outreach program and provided consultation to Caltrans for the demolition of the existing bridge.

On-Going Auxilary projects
On YBI, EMI is currently providing design and construction support as sole geotechnical consultant on auxiliary projects. The San Francisco County projects involve four new ramp/connector bridges on YBI, two of which are in steep unstable slopes requiring slope stabilization and tieback walls, a temporary detour road on geogrid-reinforced embankment, and relocation of a historic Navy building. On OTD, EMI is providing design and construction support to Bay Area Toll Authority and Caltrans for improvements to the Caltrans Interurban Electric Railway Bridge Yard.