Golden Gate Bridge

• Client:  Balfour Beatty Construction
• Location:  San Francisco, California
• Project Manager:  Hadi J. Yap
• Principal-in-Charge:  Frank L. Rollo

The Golden Gate Bridge seismic retrofit included replacement of four steel towers supporting the approximately 1000-foot-long, six-lane north  approach viaduct.  To provide temporary foundation support, 6-foot-diameter, cast-in-drilled-hole piles were installed adjacent to the towers.  The tower replacement operations limited settlement and deflection at the pile tops to less than 1/4 inch.

Treadwell & Rollo’s geotechnical services included evaluating distributed vertical and lateral forces on piles, computing pile lengths, and evaluating bending moments, shear forces, and pile top movements.  In addition, our engineers checked that computed pile top movements were less than 1/4 inch. 

During pile installation, we observed the drilling to check that soil and rock were as assumed in the analyses and, where different than assumed, modified the pile lengths.  The piles have been loaded and are performing satisfactorily.