Carquinez Bridge

Original span (1927–2007)

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. It was the first major crossing of the San Francisco Bay^[2] 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 seismicly 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.^[3] The old 1923 cantelever 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.

Parallel span (1958)

In 1958, at a cost of $38 million^[4] a second bridge was built alongside and to the east of the bridge. This new span, nearly identical to the first, was needed to accommodate the ever-increasing levels of traffic. The three-lane 1927 span, originally two-way, now served only westbound drivers while the 1958 span handled eastbound traffic.

Alfred Zampa Memorial Bridge (2003 replacement span)

Carquinez Bridge in 2006 with the 1927 span in the center.

Aerial view of Carquinez Strait and bridges, prior to construction of the new suspension bridge

At a cost of $240 million a new suspension bridge was built, to the west of the two earlier bridges, by the Joint Venture consisting of Flatiron Structures of Longmont, Co., FCI Constructors of Benicia, Ca., and the Cleveland Bridge & Engineering Company of Darlington, England.^[4]

This new bridge was named the Alfred Zampa Memorial Bridge, after an ironworker who worked on a number of the San Francisco Bay Area bridges, including the Golden Gate Bridge, and the original 1927 Carquinez span. The bridge was dedicated on November 8, 2003 and opened for traffic on November 11, 2003. Originally, the plan was to dedicate the bridge on November 15, but complications involving then just-recalled Governor Gray Davis and the transfer power to Arnold Schwarzenegger resulted in the date being moved. The coins minted to commemorate the event have the original date on them.^[5]

The new suspension bridge, consists of the south anchorage, a transition pier, the South and North towers, and the north anchorage. It has spans of 147 m, 728 m, and 181 m. for a total span of 0.66 miles (1,060 m). It features a pedestrian and bicycle path, part of a bike trail which it is hoped will eventually circle the entire Bay Area. The towers are each founded on two footings, which are each supported by six vertical, 3-metre-diameter (9.8 ft) steel shells infilled with reinforced concrete, followed by 2.7-metre-diameter (8.9 ft) drilled shafts in rock, i.e., cast-in-drilled hole, or CIDH, piles. The total length of the CIDH pile at the South Tower is approximately 89 m, with about 43 m of drilled shaft in rock. The total length of the CIDH pile at the North Tower ranges from 49 to 64 m, with about 16 to 26 m of drilled shaft in rock. The design parameters used for the South Tower piles were later confirmed by a pile load test. Additional field investigations during construction revealed significant variations in rock conditions at the North Tower, resulting in the redesign of the length of the piles. Major construction challenges encountered during construction of the South Tower piles, and the revised construction procedure, i.e., under-reaming, used by the constructor to mitigate caving.

Materials for the New Bridge came from all over the world:

• Steel Caissons for CIDH: XKT Engineering – Vallejo, California
• Orthotropic Deck Sections: IHI – Japan
• Tower and Splay Saddles:
  • Castings: Sheffield Steel – England
  • Finishing and Machining: Kvaerner – England
• Main Cable Wire: Bridon – England
• Wire for Cable Wrapping: Canada
• Cable Bands: France
• Suspenders (Hardware, Casting, Fabrication): WRCA – St. Joseph, Missouri
• (3) Maintenance Travelers Under Deck Sections: Jesse Engineering – Tacoma, Washington

Historical toll rates

Crossing the original 1926 bridge required a toll, but tolls were removed soon after the state bought the bridge in 1940. Tolls in 1926 were originally set at $0.60 per car plus $0.10 per passenger. This was reduced in 1938 to $0.45 per car plus $0.05 per passenger. After the state took ownership, tolls were immediately reduced to $0.30 per car. In 1942, tolls were further reduced to $0.25 before being removed in 1945. Tolls were reinstated in 1958 with the completion of the parallel span, set again at $0.25. It was increased to $0.35 in 1970, and then $0.40 in 1978.^[9]

The basic toll (for automobiles) on the seven state-owned bridges, including the Carquinez Bridge, was raised to $1 by Regional Measure 1, approved by Bay Area voters in 1988.^[10] A $1 seismic retrofit surcharge was added in 1998 by the state legislature, originally for eight years, but since then extended to December 2037 (AB1171, October 2001).^[11] On March 2, 2004, voters approved Regional Measure 2, raising the toll by another dollar to a total of $3. An additional dollar was added to the toll starting January 1, 2007, to cover cost overruns concerning the replacement of the eastern span.

The Metropolitan Transportation Commission, a regional transportation agency, in its capacity as the Bay Area Toll Authority, administers RM1 and RM2 funds, a significant portion of which are allocated to public transit capital improvements and operating subsidies in the transportation corridors served by the bridges. Caltrans administers the "second dollar" seismic surcharge, and receives some of the MTC-administered funds to perform other maintenance work on the bridges. The Bay Area Toll Authority is made up of appointed officials put in place by various city and county governments, and is not subject to direct voter oversight.^[12]

Due to further funding shortages for seismic retrofit projects, the Bay Area Toll Authority again raised tolls on all seven of the state-owned bridges in July 2010. The toll rate for autos on the Carquinez Bridge was thus increased to $5.^[13]