Alvord Lake Bridge

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 convert|64|ft|m wide with a convert|20|ft|m|sing=on span. 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.

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 the 1970s.