September 12, 2014
San Francisco-Oakland Bay Bridge New East Span Wins 2014 Award of Excellence from Structural Engineers Association of California
T.Y. Lin International (TYLI), a globally recognized full-service infrastructure consulting firm, announces that the new East Span of the San Francisco-Oakland Bay Bridge (East Span) has won the 2014 Award of Excellence in the Infrastructure Category, for excellence in structural engineering analysis and design, from the Structural Engineers Association of California (SEAOC). TYLI, in a joint venture with Moffatt & Nichol, was the Engineer of Record on the immense replacement project, working in conjunction with California Department of Transportation, the Metropolitan Transportation Commission and the California Transportation Commission. The Award of Excellence was presented to the project team at the SEAOC 2014 Annual Convention in Indian Wells, CA, on September 11, 2014.
“T.Y. Lin International is extremely pleased that the Structural Engineers Association of California has honored the new East Span of the San Francisco-Oakland Bay Bridge with this prestigious award,” said Alvaro J. Piedrahita, P.E., TYLI President and Chief Executive Officer. “As Engineer of Record, we designed a signature structure that blends harmoniously with the Bay Area landscape while also setting the highest standards for seismic safety.”
Representing the largest public works project in California history, the 2.2-mile-long East Span comprises four elements: the Self-Anchored Suspension Span (SAS), with a main span length of 1,263 feet; the 1.2-mile-long Skyway, which sweeps up from the Oakland shoreline and connects to the SAS; the Oakland Touchdown linking the Skyway to Interstate 80; and the Yerba Buena Island Transition Structure, which connects the SAS to the island. The design of the replacement bridge met stringent seismic criteria, including a 150-year design life and the ability to open to emergency vehicles shortly after the most powerful earthquake that can be predicted in a 1,500-year period.
The new East Span is the longest single-tower, self-anchored suspension span in the world and the world’s widest bridge. Located in a high seismic zone, it is the first suspension bridge to use fusible shear link beams to interconnect the four legs of its 525-foot-tall tower. The shear links allow the tower legs to move independently during an earthquake, protecting the structure. The SAS also utilizes a single, 4,550-foot-long suspension cable - the longest looped suspension cable ever used for a bridge. Because the geological conditions of the bay made it seismically and economically unfeasible to anchor a suspension cable system in the ground at either end of the structure, the main cable is anchored in the superstructure itself.
The parallel viaducts of the Skyway, the longest portion of the East Span, are segmental bridges, erected in balanced cantilever, with a typical span of 525 feet, and carry 10 lanes of traffic in both directions (five westbound and five eastbound). Throughout the SAS and Skyway decks, expansion joints allow several feet of movement and hinge pipe beams transfer bending and shear across the expansion joints, with sacrificial fuse sections that absorb seismic energy and protect the structures during an earthquake. Skyway foundations were driven over 300 feet below the surface of the Bay to reach stable soils, utilizing a process used for creating secure foundations for offshore oil rigs.
One of the busiest toll crossings in the United States, the new East Span opened to traffic on September 2, 2013. To date, the landmark bridge has also won the 2014 Special Recognition Award from the California Transportation Foundation, the 2014 Globe Award from the American Road & Transportation Builders Association, the 2013 Project of the Year Award from the American Society of Civil Engineers (ASCE), Region 9, and the 2013 Outstanding Transportation Project Award from ASCE, San Francisco Section.