Alvord Lake Bridge

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Alvord Lake Bridge
HAER-Alvord Lake.jpg
A view of the Alvord Lake Bridge looking toward the east
Coordinates 37°46′08″N 122°27′18″W / 37.7690°N 122.4549°W / 37.7690; -122.4549Coordinates: 37°46′08″N 122°27′18″W / 37.7690°N 122.4549°W / 37.7690; -122.4549
Crosses Pedestrian entrance to San Francisco's Golden Gate park
Locale San Francisco
Official name Alvord Lake Bridge
Heritage status American Society of Civil Engineers civil engineering landmark
Material Reinforced concrete
Width 64ft
Longest span 20ft
No. of spans 1
Designer Ernest L. Ransome
Opened 1889

The Alvord Lake Bridge was the first reinforced concrete bridge built in America. It was built in 1889 by Ernest L. Ransome, an innovator in reinforced concrete design, mixing equipment, and construction systems. The bridge was constructed as a single arch 64 feet (20 m) wide with a 20-foot (6.1 m) span .[1] Ransome is believed to have used his patented cold-twisted square steel bar for reinforcement, placed longitudinally in the arch and curved in the same arc. The face of the bridge was scored and hammered to resemble sandstone, the interior features calthemite [2] "stalactites" (concrete derived secondary deposits) which have subsequently grown in later years after the initial construction.

E.L. Ransome left San Francisco a few years later, frustrated and bitter at the building community's indifference to concrete construction. Ironically, the city's few reinforced concrete structures, including the Alvord Lake Bridge, survived the 1906 earthquake and fire in remarkable shape, vindicating Ransome's faith in the method.

The Alvord Lake Bridge, which arches over a pedestrian entrance to San Francisco's Golden Gate park, was designated a civil engineering landmark by the American Society of Civil Engineers in 1969.


  1. ^ Jackson, Donald (1996), Great American bridges and dams, New York: Wiley, ISBN 978-0-471-14385-7
  2. ^ Smith, G.K. (2016). "Calcite straw stalactites growing from concrete structures", Cave and Karst Science 43(1), 4-10.