Background
When it was constructed in 1930, the East Span of the San Francisco-Oakland Bay Bridge was the world's longest cantilever bridge. Today, the bridge still holds the record for the deepest bridge pier (242 feet below water level).

In 1989, a section of the East Span of the San Francisco-Oakland Bay Bridge collapsed during the Loma Prieta earthquake, causing a major disruption in the Bay area transportation system. The bridge is a key link in the system, and with about 270,000 commuters daily, carries the largest volume of traffic of any bridge in the world. Repairs were made and a long-term seismic safety program was initiated. However, when seismic retrofit costs were compared with the cost of bridge replacement, it was determined reconstruction of the bridge was more cost effective.

The new bridge will span the Bay between Yerba Buena Island and the City of Oakland, replacing the existing steel truss section. The new bridge will include:

• Transitions structures on Yerba Buena Island
  
• An asymmetric single-tower self-anchored suspension cable, main-span structure offshore from Yerba Buena Island
  
• A four frame skyway structure extending from the main-span structure to Oakland
  
• Oakland shore approach structures
  
• An earthen fill transition from the Oakland shore approach to existing roadways
  
  

Fugro's Role
Fugro-Earth Mechanics, a joint venture formed by Fugro West, Inc., (lead partner) and Earth Mechanics, Inc., was selected by Caltrans to conduct geologic and geotechnical studies for the bridge reconstruction. The studies would help determine the type of bridge that could be constructed and best location for the new bridge. To minimize traffic impacts the new bridge will need to be completed before the old bridge is put out of commission.

Geotechnical services provided by Fugro included:

• Site investigations including over water and land geotechnical exploration and marine geophysical surveys.
  
• Site characterization to define the distribution and properties of soil and rock units, and to evaluate the potential for local fault hazards.
• Foundation engineering for the assessment of alternative alignments and design of foundation systems
  
• PIDP (Full-scale pile installation demonstration project) development and execution.
  
• Geographic Information System (GIS) development.
• Future design support during construction