TYLin, as Lead Engineer in a joint venture, designed the replacement of the eastern span of the San Francisco-Oakland Bay Bridge between San Francisco and Oakland, California.
TYLin was the Engineer of Record for the dramatic, 2,047-foot-long self-anchored suspension span (SAS) and the 1.2-mile-long precast segmental Skyway viaducts. Both structures are signature components of the 2.2-mile-long San Francisco-Oakland Bay Bridge New East Span (East Span), also known as the Bay Bridge.
Located between two major California fault lines, the seismically resilient East Span opened to traffic as the world’s longest single-tower, self-anchored suspension bridge (1,263-foot main span). The mega project also represents the largest public works project in California history.
TYLin’s unique design for the 525-foot-tall SAS tower consists of four steel shafts connected by shear link beams that are designed to protect the load-bearing shafts in the event of an earthquake.
The SAS utilizes a single 4,550-foot-long cable, the longest looped suspension cable ever used for a bridge. The cable drapes from the top of the tower and loops back below the west end, with slender suspender cables that attach the main cable to the girders beneath the roadway deck.
The Skyway makes up the longest section of the East Span. Featuring sweeping, side-by-side decks, the twin viaducts accommodate a total of 10 lanes of traffic (five in each direction) and a steel bicycle-pedestrian path.
TYLin designed the Skyway to have an optimum span length of 524 feet. The viaducts are composed of five frames to reduce the number of expansion joints needed. The frames serve the dual purpose of accommodating sliding movement while maintaining rigidity to resist seismic motion.
- From concept and final design through construction support services, TYLin provided bridge engineering expertise to the California Department of Transportation (Caltrans) for all phases of the project.
- The lifeline structure is designed to withstand the strongest ground motions engineers can expect in a 1,500-year period.
- TYLin’s design makes the East Span the first suspension bridge with no connection between the deck and tower.
- The project marks the first use of seismic energy-absorbing shear link beams in the tower of a cable-supported bridge.
- Precast girder segments for the Skyway weigh up to 750 tons each, the largest ever built in the world at the time.
- State-of-the-art hinge pipe beams were built at the expansion joints between the bridge frames.
Image credit: Sam Burbank Photography