A Bathtub for the South Tower

To reach the site of the south tower foundation, workers constructed a temporary roadway on a timber access trestle, or wharf, from the San Francisco shore. The dangers of the exposed location soon became apparent in 1933, when a freighter collided with the trestle. Two months later, over half of the repaired structure collapsed in a storm. Undaunted, the workers restored the structure and continued their work.

The plans called for a huge oval-shaped concrete barrier, or fender, to protect the base of the south tower from ship collisions during fog. To build the fender, workers placed the concrete through tubes underwater into wood forms, where it set.

When the fender was built up above the water level and was visible, the workers called it a "giant bathtub." For the foundation pier, the base on which the tower would stand, workers placed concrete underwater to fill the bottom portion of the fender. After pumping out the remaining 9.4 million gallons (35.6 million liters) of seawater, workers inside the "bathtub” completed the placement of reinforcing steel and concrete.

Captions:

Top left:An access wharf extended from the San Francisco shore to the south tower. Bev Washburn Collection, Golden Gate Bridge, Highway and Transportation District

Bottom left: A cross section of the south tower fender walls and foundation. The illustration was done by Chesley Bonestell, a designer who worked on architectural details of the Chrysler Building in New York and other prominent buildings, and who later became one of the most famous illustrators of space exploration. Chesley Bonestell, Golden Gate Bridge, Highway and Transportation District

Center: The foundation's reinforced concrete being built up from the bedrock of the seafloor. The vertical tubes are the inspection wells that allowed access down through the concrete. Bev Washburn Collection, Golden Gate Bridge, Highway and Transportation District

Right: Once the concrete work was done, the erection of the steel for the south tower began in January 1935 and was completed in just six months. Bev Washburn Collection, Golden Gate Bridge, Highway and Transportation District

. This historical marker was erected in 2012 by Golden Gate Bridge, Highway and Transportation District. It is in Presidio of San Francisco in San Francisco City and County California