Carquinez Bridge

The Carquinez Bridge is a pair of parallel bridges spanning the Carquinez Strait at the northeastern end of San Francisco Bay. They form the part of Interstate 80 between Crockett and Vallejo, California, United States.

The name Carquinez Bridge originally referred to a single cantilever bridge built in 1927, which was part of the direct route between San Francisco and Sacramento. A second parallel cantilever bridge was completed in 1958 to deal with the increased traffic.

Later, seismic problems made the 1927 span unsafe in case of an earthquake, and led to the construction, and 2003 opening, of a replacement: a suspension bridge officially named the Alfred Zampa Memorial Bridge, in memory of iron worker Al Zampa, who played an integral role in the construction of numerous San Francisco Bay Area bridges. The Alfred Zampa Memorial Bridge carries southbound traffic from Vallejo to Crockett, and the 1958 cantilever span carries northbound traffic.

The first regular crossing of the Carquinez Strait began in the mid-1800s as a ferry operated between the cities of Benicia and Martinez, six miles upstream from the bridge site. Auto service started on this route in 1913. A train ferry operated between Benicia and Port Costa from 1879 until 1930 when a rail bridge opened. Ferry service at the site of the bridge started in 1913 by the Rodeo-Vallejo Ferry Company.

The original steel cantilever bridge was designed by Robinson & Steinman and dedicated on May 21, 1927. Prior to this, crossing the Carquinez Strait necessitated the use of ferries. The bridge cost $8 million to build (equivalent to $148.28 million in 2025). It was the first major crossing of the San Francisco Bay and a significant technological achievement in its time.

Upon its completion, the span became part of the Lincoln Highway. This historic transcontinental roadway's original alignment, like the Transcontinental Railroad that preceded it nearly sixty years earlier, chose to avoid crossing the Carquinez Strait entirely. The preferred option, given the engineering limitations of the day, was to skirt around the Delta by going south from Sacramento through Stockton, then proceeding west across the San Joaquin River and over the Altamont Pass, and finally reaching Oakland from the south; a route that would later become U.S. Route 50 and ultimately Interstates 5, 205, and 580. This circuitous route, several miles longer, and traversing a rather formidable mountain pass, was preferable to crossing the Carquinez Strait, a deep channel with strong currents and frequent high winds. For decades, building a bridge across the Carquinez Strait was considered prohibitively expensive and technologically risky. Once the bridge was built however, driving from Sacramento to the East Bay became much more direct. The Carquinez Bridge provided a welcome alternative route from the Central Valley to the Bay Area, one that no longer required loading one's vehicle onto and off of a ferry. With the bridge completed, the Lincoln Highway was realigned to cross the Sacramento River, then proceed southwest through Davis and Vallejo, across the Carquinez Bridge, and along the shores of the San Pablo and San Francisco bays to Richmond and Oakland; becoming U.S. Route 40, and ultimately Interstate 80.

After the Loma Prieta earthquake engineers determined that the aging 1927 span was seismically unstable, and that a retrofit was impossible. The decision was made to replace it with a new suspension bridge. The 1927 span was temporarily used to hold eastbound traffic while the 1958 eastbound span underwent a seismic retrofit, deck and superstructure rehabilitation, and painting to extend its serviceable life. The old 1927 cantilever bridge was dismantled three years after the opening of its replacement; with completion on September 4, 2007. A 3,000-pound bronze bell atop one of the bridge piers was removed and placed into storage. The bell will eventually be displayed in a new museum to be built at the Oakland end of the San Francisco–Oakland Bay Bridge.

At a cost of $38 million (equivalent to $424.05 million in 2025),a parallel bridge was built just east of the 1927 bridge. The new bridge carried all traffic for a few months after it opened in November 1958, then after new ramps were built, the three-lane 1927 span, originally two-way, served westbound traffic while the four-lane 1958 span handled eastbound traffic.