A Tunnel Takes Shape

These photographs depict early work on the Yerba Buena Tunnel, which connects the eastern and western spans of the San Francisco-Oakland Bay Bridge. At the time of its construction, this structure was the largest bore tunnel ever built, its finished size being 76 feet across at its widest point, and 58 feet high at the crest of the arch.

Temporary railroad tracks, built to move excavation debris, can be seen in the top-most photograph. The excavated muck was transported via a disposal chute to a worksite north of Yerba Buena Island, where the U.S. Army Corps of Engineers were starting the long process of filling in shoals to create Treasure Island, future site of the Golden Gate International Exposition.

The bottom photograph shows the construction of the viaduct carrying the eastern span to the tunnel entrance.

Identification Information: Dept. of Public Works, San Francisco-Oakland Bay Bridge Construction Photographs (F2516:1-93).
Top: West Portal, 05/22/1934: Box 21 (C5230), photograph 5-700.
Bottom: Arch, 08/06/1935: Box 21 (C5230), photograph 5-1610.