Alvord Lake Bridge (San Francisco, California)

USA / California / San Francisco / San Francisco, California / Kezar Drive
 bridge, historic landmark
The bridge is a single arch, 64 feet wide with a 29-foot-long span.
Built in 1889 by Ernest L. Ransome of New York, this reinforced concrete arch bridge is believed to be the oldest concrete bridge in the United States that used steel reinforcing bars to improve the behavior of the concrete.
The reinforcement consists of a series of square cold-twisted steel reinforcing bars, an invention of Ransome. They were embedded longitudinally near the underside of the arch and bent in approximately the same curve as the arch. This, the Alvord Lake Bridge, has a 29-foot-long span, but by the turn of the century reinforced concrete arch bridges were being built with spans more than 100 feet in length.
Alvord Lake Bridge, along with many of Ernest Ransome's other re-inforced concrete buildings, survived the 1906 San Francisco earthquake with no damage.
The pedestrian tunnel under (or through) the bridge is notable for the rather fanciful cast concrete "stalactites" in the ceiling.
Wikipedia article: http://en.wikipedia.org/wiki/Alvord_Lake_Bridge
Nearby cities:
Coordinates:   37°46'8"N   122°27'17"W

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  • A podcast on this bridge: http://99percentinvisible.org/episode/episode-81-rebar-and-the-alvord-lake-bridge/
This article was last modified 5 years ago