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Bay Bridge Work Focuses on Suspension Cables

Credit
Joey Kotfica

Beneath the western approach to the Bay Bridge on San Francisco's Rincon Hill, workers atop scaffolding in a makeshift, white-tarped tent are pounding wedges into the span's main suspension cables to perform an in-depth inspection of the thousands of steel wires that comprise each cable.

It's the first time the insides of the cables have been systematically inspected since the bridge opened in 1936. The $21.6 million investigation by Caltrans and the Bay Area Toll Authority (BATA) started last month and is expected to conclude in June of 2025. The project is funded with toll dollars.

Each of the Bay Bridge suspension cables — the "backbone" of the span — is made up of more than 14,000 galvanized wires that are 0.195 inch in diameter, somewhere in size between spaghetti and a pencil. The orange color on the outside edge of the wires shown in the photos below is residue from a protective primer and paste used to prevent corrosion of the steel during the original construction of the Bay Bridge West Span. 

Cable inspection
Credit: Mark Prado

As the plastic wedges are driven with hammers and mallets into the cables, a gap opens to allow for visual inspection. Samples will be removed and sent to a lab with new wires put in their place. Inspectors will examine the wires at 10 different locations between Rincon Hill and Yerba Buena Island to determine the cables' condition. Other aspects of the work will look at how air flows through the cables. 

The Bay Bridge cable investigation is part of the BATA-Caltrans team's never-ending responsibility to keep all seven of the Bay Area’s state-owned toll bridges in good working order. BATA earlier this year approved an asset management policy and a set of objectives for the continued maintenance and operation of the bridges. The policy is based on four principles: focusing on people and safety; addressing maintenance and rehabilitation costs over each bridge’s entire life cycle; adopting a quantifiable approach to asset management; and promoting sustainability and ongoing enhancements to the toll bridge program. 

Cable inspection
Credit: Mark Prado

 

BATA already has completed a comprehensive life-cycle analysis to guide maintenance and rehabilitation plans for the eastbound Carquinez Bridge and the southbound Benicia-Martinez Bridge, and is now working with Caltrans to prepare an updated assessment of all seven toll bridges’ maintenance needs over the next 50 years. This assessment is scheduled for completion next year. 

In partnership with Caltrans, BATA since 2007 has invested $1.7 billion in toll funds on restoring the bridges and associated toll facilities, a figure that does not include the nearly $9 billion Toll Bridge Seismic Retrofit Program completed in 2013. 

BATA’s Capital Improvement Plan targets another $1.9 billion for toll bridge upkeep through 2033. With the Bay Bridge West Span, the Richmond-San Rafael Bridge (1956) and the eastbound Carquinez Bridge (1958) now senior citizens, and the original Benicia-Martinez (1962), San Mateo-Hayward (1967), Antioch (1978) and Dumbarton (1984) bridges into or approaching middle age, a growing share of toll dollars will be needed to keep these bridges in a state of good repair.

 

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