On back: "SAN FRANCISCO-OAKLAND BAY BRIDGE; Walter G. Swanson; 500 Sansome St. - GArfield 1415. File 900.11, B-12/MW. The 'Off' ramp for the San Francisco-Oakland Bay Bridge is now under construction at Clementina and First Streets where a pile driver is driving test piles to determine the lengths of concrete piles that will support the bridge viaduct. Traffic will be pouring off of this ramp from Eastbay inside of a year, according to Chief Engineer C. H. Purcell."