Folder: S.F. Bridges-Bay-Construction-Yerba Buena Island.
Printed on back: "Aerial view looking west toward San Francisco showing part of the East Bay Crossing and the West Bay Crossing of San Francisco-Oakland Bay Bridge. In the foreground, traveler derrick may be seen erecting the second 500-Foot Span. On Yerba Buena Island (center of photo) the erecting of the Yerba Buena Island Spans is in progress. Immediately to the left of this steel work the world's largest bore tunnel is under construction. At top of photo may be seen the West Bay Crossing which will consist of tow separate suspension spans with a common center anchorage. All four Towers are erected and the Concrete Center Anchorage is ready for the erection of steel work preparatory to cable spinning operations. C.H. Purcell is Chief Engineer of the San Francisco-Oakland Bay Bridge.".