Folder: S.F. Bridges-Bay-Yerba Buena Tunnel.
On back: "The giant tunnel of the San Francisco-Oakland Bay Bridge underwent its spring cleaning yesterday. It took the combined efforts of the Bridge's fire engine, its street sweeper and electrical truck, and a crew of seven to shine and polish the tunnel's 50,540 square feet ot tile lining. The men started work Wednesday morning at one o'clock, worked until sunrise, and put the finishing touches to the job early this morning between the hours of midnight and 4:00 a.m. It took a total of ten hours to wash this world's largest vehicular bore tunnel, and 3,200 gals. of water."
"California Toll Bridge Authority and Gabriel Moulin Photo."
