San Francisco Bay
Year Constructed
Year Retrofitted
Structural Engineer(s)
Original Board of Architects: Arthur Brown, Jr., John J. Donovan and Timothy L. Pflueger
Main Contractor
American Bridge Company and Columbia Steel Company
New Eastern Span at Night
New Eastern Span at Night
New Eastern Span
New Eastern Span
Source: Carlos Avila Gonzalez / The Chronicle
Western Span
Western Span
Source: Caroline Culler
Western Span at Night
Western Span at Night
Source: ChristianSchd
Old Eastern Span
Old Eastern Span
Source: Dan Bluestein
Western Span under Construction
Western Span under Construction
Source: San Francisco Public Library
Significance to Structural Engineering History in Northern California

When the San Francisco – Oakland Bay Bridge opened on November 12, 1936 it was the longest crossing over water in the world (4.3 miles) and the most expensive bridge ever built at the time ($77.2 million). The bridge was considered one of the most remarkable engineering feats of its time. Today, the San Francisco-Oakland Bay Bridge is a critical transportation link in the San Francisco Bay Area.

Structure Description

The San Francisco – Oakland Bay Bridge was conceived as early as the gold rush days, but construction did not begin until 1933. Design and construction was overseen by Chief Engineer Charles H. Purcell and a nationally renowned consulting Board of Engineers that included Leon Moisseiff, Ralph Modjeski, Daniel Moran, Charles H. Derleth Jr. and Henry J. Brunnier. Built by the American Bridge Company and Columbia Steel Company at a reported cost of $77 million, the bridge opened on November 12, 1936, six months before the Golden Gate Bridge. It originally carried automobile traffic on its upper deck, and trucks and interurban streetcars on the lower, but after the Key System abandoned rail service, the lower deck was converted to all-road traffic as well. In 1986, the bridge was unofficially dedicated to former San Francisco Mayor James Rolph.

The bridge has two sections of roughly equal length totaling almost 4 and a half miles. The section west of Yerba Buena Island, officially known as the Willie L. Brown Jr. Bridge after the former San Francisco Mayor and California State Assembly Speaker, connects downtown San Francisco to Yerba Buena Island; and the newer eastern section connects the island to Oakland.

The western section is constructed of two double tower steel cable suspension systems each spanning 2310 feet connected by a massive center concrete anchorage. The four towers rise 505 feet above the bay. Clearance below the western bridge section to the bay is 220 feet. The bottom of the center anchorage and tower caissons are 235 feet below the bay surface.

The largest span of the original eastern section was a riveted steel trussed cantilever bridge which connected to a riveted steel truss girder section at the east end. During the 1989 Loma Prieta earthquake, a portion of the eastern section’s upper deck collapsed onto the lower deck and the bridge was closed for a month. Reconstruction of the eastern section of the bridge as a causeway connected to a self-anchored single tower suspension bridge began in 2002. The new eastern section opened September 2, 2013, at a reported cost of over $6.5 billion. Unlike the western section and the original eastern section of the bridge, the new eastern section is a single deck with eastbound and westbound lanes on each side making it the world’s widest bridge. The single tower suspension bridge spans 1400 feet with clearance below to the bay of 190 feet.

  • ASCE Historical Civil Engineering Landmark
  • AASHTO America’s Transportation Award, Grand Prize and Best Use of Innovation Award (2014)
  • International Association for Bridge and Structural Engineers Outstanding Structure Award (2015)
  • International Bridge Conference George S. Richardson Medal for outstanding achievement in bridge engineering (2015)
  • FIDIC Outstanding Project of the Year Award (2016)
Interesting Facts
  • Original toll in 1936: $0.65 each way.
Related Event(s)