On back: "SAN FRANCISCO-OAKLAND BAY BRIDGE; Walter G. Swanson; 500 Sansome St. - GA rfield 1415. File 900.11 B-12/BD. Aerial view of Pier W-4, Concrete Center Anchorage of the twin suspensions spans (West Bay Crossing) showing concrete poured to an elevation of 222 feet above water level and forms for lower deck slab girders being placed. The height of the Concrete Center Anchorage from water level to top of concrete will be 235.18 feet according to C. H. Purcell, Chief Engineer of the San Francisco-Oakland Bay Bridge."
