The existing south access road to San Francisco’s Golden Gate Bridge, known as Doyle Drive or Route 101, is structurally and seismically unsafe, and requires replacement. Built in 1936, Doyle Drive has reached the end of its serviceable life. The foundations for the new South Viaduct Bridge presented quite a challenge to Malcolm Drilling Co. due to the requirement for deep, large-diameter drilled shafts installed adjacent to historic landmarks. Drilled shafts with 12-foot diameters were constructed to depth of approximately 200 feet.