San Francisco-Oakland Bay Bridge Deck Resurfacing Revisited

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Title: San Francisco-Oakland Bay Bridge Deck Resurfacing Revisited

Author(s): Charles Seim and Robert Gaul

Publication: Special Publication

Volume: 169

Issue:

Appears on pages(s): 75-86

Keywords: Aggregates; bridge decks; epoxy resins; polymer concrete

Date: 5/1/1997

Abstract:
The San Francisco Oakland Bay Bridge was designed for six lanes of automobiles on a lightweight concrete upper deck. Two lanes of truck traffic with a third switch lane supported on a conventional concrete slab shared the lower deck space with two commuter rail tracks. Instead of using paint to delineate the lanes on the upper deck, ceramic tile embedded into a concrete mortar wear coat acted as a lane striping. This eliminated the paint re-striping maintenance operation. It was expected that the bridge could operate that way for a long time when it was opened to traffic with much fanfare, automobile caravans and political speeches on November 12, 1936. The bridge carried approximately 25,000 vehicles per day during its first year. In 1957, the commuter rail line ceased to operate. Traffic volume had increased to nearly 100,000 vehicles per day while 25% of the capacity of the bridge was not beiig utilized. In 1958 the reconstruction of the Bay Bridge began. The rails were removed, precast lightweight concrete panels were added, the approaches to the two decks were modified and the upper deck was strengthened to accommodate the new truck loading. In 1963, trffic capacity was increased by converting the facility into five unidirectional mixed vehicle and truck traffic lanes on each deck. To do so required removing or covering the embedded ceramic tile lane boundaries. Removal would be tedious and patching the resulting holes expensive. The alternative of covering them with a thin surfacing was easier and, in addition, protected the concrete deck which was beginning to show some transverse cracking and chloride intrusion. A coal-tar epoxy binder with quartz beach sand broadcasted over the sprayed-on binder was applied yielding a total thickness of approximately 5 mm. The lower deck was resurfaced in 1964 utilizing the same system. The coal-tar epoxy held up