Design Review Process  

The design for the new East Span has been developed with extensive input from public hearings, public comment on the environmental document, and coordination with the Metropolitan Transportation Commission (MTC). Two advisory committees were created by MTC specifically for this project: The Bay Bridge Design Task Force (BBDTF) and their technical advisory committee, the Engineering and Desing 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.

For more information on the East Span design review process, visit the East Span Project newsletter archives.

 Several alignments were considered for the new East Span. Since the existing bridge must be operational 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 has identified northern alignment N6 as the Preferred Alternative for the new East Span.

The N6 alignment would avoid portions of the Bay where geologic conditions would increase construction complexity and cost. The N6 alignment would allow for easier access to bedrock to construct the main span tower. The alignment would also accommodate the East Bay Regional Park District's (EBRPD) planned Gateway Park on the Oakland shore and minimize 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. For more information about Caltrans' coordination with local agencies and project stakeholders, click here.

MTC's Recommended Design for New East Span

  MTC and EDAP have also recommended the N6 alignment. EDAP concluded that this replacement alternative would create the best "gateway" to Oakland, while enhancing vistas, and allowing more flexibility to design and build a cable-supported span. The N6 replacement alternative would provide expanded views toward the Golden Gate, Mt. Tamalpais, and portions of the San Francisco skyline for westbound motorists. As with any of the alignments considered, eastbound motorists would have panoramic views of the Oakland skyline and the East Bay hills.

In June 1998, MTC recommended that Caltrans pursue a signature bridge design option which includes a steel single-tower suspension span over the shipping channel near Yerba Buena Island and a concrete pier-supported "skyway" from the suspension span to Oakland. MTC noted that the suspension span's single-tower and self-anchoring features represent important advances in bridge and seismic design and that the design would provide an appropriate and distinctive gateway to the East Bay. The catenary forms of the suspension span also relate to the context of the proposed bridge, mirroring the lines of the West Span of the Bay Bridge and the Golden Gate Bridge.

After considering several possible profiles to accommodate the grade change between the tunnel on Yerba Buena Island and the Oakland shore, MTC recommended an elevated profile for the new span. This means that the suspension span will remain at a relatively constant grade at approximately the level of the tunnel and the skyway will slope gradually down toward the Oakland shore. [The diagram shown here is vertically exaggerated for illustration purposes].

EDAP and the design team envision the bridge as a "white line" across the Bay. The new bridge rises from the Oakland shore toward the suspension span over the shipping channel and then connects to the existing tunnel on Yerba Buena Island. All vertical elements, including the tower, piers, and light standards have been designed with faceted forms to emphasize the clean modern lines of the structure and intensify the effects of light and shadow. Though the concrete portions of the bridge are not bright white, their pale gray color and clean linear character support the "white line" vision for the bridge. The bridge will carry eastbound and westbound traffic on separate, parallel road decks. The decks will converge into a double-deck configuration as they approach the Yerba Buena Island tunnel and the West Span of the Bay Bridge. The bicycle/pedestrian path terminates on the island.

From the Oakland shore to the suspension span, the bridge consists of a pier-supported concrete skyway. Designed for optimum seismic performance with consideration of the deep Bay mud in this area, the skyway will appear as a clean pale line accented by the faceted vertical forms of the pier and light standards. The roadway light standards increase in height as the bridge rises over the water and approaches the suspension span.

The asymmetrical suspension span has a longer forward span (east of the tower) than back span which provides a more gradual transition from the gently sloping skyway and gives the East Span a distinctive silhouette. The 530-foot tall steel tower is located between the two road decks and is made up of four pentagonal columns connected by a series of horizontal link beams. A single suspension cable wraps over the tower and underneath the western end of the span, then wraps over the tower again and anchors in both roadway decks at the eastern end. Suspenders connect diagonally from this cable, which crosses above the roadway to the outside edges of the decks.

The above design recommendations were also adopted by the San Francisco Bay Conservation and Development Commission (BCDC), a state agency dedicated to protecting and enhancing the Bay and ensuring that the surrounding development incorporates maximum feasible public access.

MTC continues to provide key input to the East Span Project to ensure that region-wide interests are appropriately addressed. A description of MTC's recent recommendations are listed below.

MTC continues to support inclusion of a "light pipe" along the outside edges of the East Span to unify the appearance of the bridge and add to its distinctiveness with a white line of light. However, the light pipe is not an eligible amenity for which MTC can extend the seismic retrofit toll surcharge. MTC will seek funding for this design enhancement in the context of the expected legislative deliberations in 2001 on providing additional funding for the overall toll bridge seismic retrofit program. Caltrans is making provisions in the current design so that the light pipe can be added later if funding is identified.

 The East Span would usher in the 21^st century and would serve as a bright new gateway connecting San Francisco, Oakland, and the East Bay. Caltrans’ design team has developed a lighting strategy that would appropriately showcase this important landmark. Caltrans' Project Manager Brian Maroney says that lighting for the East Span Project is intended to serve two purposes; safety and aesthetics.

A bridge is a true landmark. It joins two places and acts as an invitation to enter a community. Caltrans lighting designers are working to ensure that the bridge will be a significant landmark for the 21^st century.