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East Span Design Basics
The new East Span will consist of four distinct structures:
The new 2.1-mile span will have two side-by-side road decks, each with five lanes and emergency shoulders. Parallel roadways were chosen over a double-deck configuration to achieve stronger seismic stability, economic construction and better aesthetics. A 15-foot-wide bicycle-pedestrian path with seven viewing platforms will be located on the south side of the bridge.
The Skyway section, scheduled for completion in the summer of 2006, will consist of roadway sections supported by 28 concrete and steel piers. These sections will be made in Stockton and transported by barge to the bridge site. When finished, the roadway will slope gradually from the Suspension Section to the Oakland shore.
The bridge was designed first and foremost with seismic safety in mind. (For more information, go to the Overview: Seismic Safety page.)
But designers and community leaders were also concerned with aesthetics. Envisioning the bridge as a "white line" across the Bay, they chose a simple design that would accent its surroundings without detracting from them, yet one that would provide a signature profile that people of the Bay Area would be proud of.
In keeping with that idea, the skyway section has a clean, linear profile. An asymmetrical Suspension Section was chosen to provide a distinctive gateway to the East Bay and to mirror the lines of the western span of the Bay Bridge and the Golden Gate Bridge. To provide a unique silhouette, the Suspension Section will have a longer eastern span from the tower than the western side.
All vertical elements, including the tower, piers, and light standards have been designed to emphasize the lean lines of the bridge. Unique light poles and railings will be used to join the designs of each bridge segment and create a unified appearance.
Several alignments were considered for the new East Span, but since the existing bridge must carry vehicle traffic while the new bridge is constructed, the new bridge must be built either north or south of the existing bridge. After extensive environmental review and geologic testing, Caltrans identified a northern alignment as the preferred route.
The northern alignment avoids portions of the Bay where geologic conditions would increase construction complexity and cost. It also allows for easier access to bedrock to construct the main span tower. The alignment also accommodates the East Bay Regional Park District's planned Gateway Park on the Oakland shore and minimizes conflicts with facilities and operations of the U.S. Coast Guard, the East Bay Municipal Utility District's sewer outfall and the Port of Oakland's expansion plans.
The northern alignment also creates the best eastbound "gateway" to Oakland while expanding vistas toward the Golden Gate, Mt. Tamalpais and portions of the San Francisco skyline for westbound motorists.
A word about the design process
The design for the new East Span was developed under guidelines established by Caltrans and Gov. Gray Davis. The governor mandated that the new East Span be a "lifeline" bridge capable of being reopened within 24 hours of a major earthquake.
Among Caltrans requirements: The Suspension tower should not be of a height that would overwhelm the towers on the western side; the bridge should not have two decks; the design should include a signature span; the approach to the span should be a skyway structure.
The design was also influenced by input from several other organizations and the public. The Metropolitan Transportation Commission (MTC), which oversees transportation planning and financing in the Bay Area, created two advisory committees specifically for this project: The Bay Bridge Design Task Force (BBDTF) and the Engineering and Design Advisory Panel (EDAP). The BBDTF has reviewed the East Span Project from the initial stages of choosing the bridge design materials and alignment through detailed development of elements such as lighting and a bicycle/pedestrian path.
The contract for the design was awarded to a joint venture of T.Y. Lin International and the firm Moffatt & Nichol.
T.Y. Lin engineers and personnel designed the Suspension and Skyway sections. Moffatt & Nichol designed the foundations for the main span and viaducts, ship collision measures, and design of the YBI viaducts, YBI detours, YBI Transition structure and the Oakland shore structures.