Bay Bridge

Northern vs. Southern Alignment

The question of where to locate a new eastern span of the Bay Bridge — north or south of the existing span — generated considerable discussion. Caltrans examined a total of nine northern and southern alignments located at varying distances from the existing span. They narrowed the options down to three potential alignments: two northern and one southern. For reasons outlined in the Bridge Alignment Comparison below, MTC and its Engineering and Design Advisory Panel concluded the northern alignment, identified as N-6, would be the safest and most cost-effective route.

In designing the new East Span, care is being taken not to encroach on the historic Admiral Nimitz House on Yerba Buena Island.
Existing	Northern (N-6)	Southern (S-1)
The view from Yerba Buena Island (as it would appear from the historic Admiral Nimitz House) remains essentially the same regardless of the bridge alignment. (Click images to enlarge)

The city of Oakland, Port of Oakland, and East Bay Regional Park District prefer the N-6 alignment.By August 2000, the viaduct portion of the new span's design, based on the N-6 alignment, was 100 percent complete.

Due to the proximity of the N-6 alignment to U.S. Navy property on Yerba Buena Island that is slated to be transferred to the city and county of San Francisco for redevelopment following the closure of Treasure Island Naval Station , the Navy and the mayor of San Francisco favored the southern alignment, identified as S-1.

At the request of the White House, the Army Corps of Engineers evaluated the contradictory analyses of the alignment by Caltrans and the city of San Francisco. The Corps report concluded that changing the design to build the new bridge on the southern alignment as preferred by San Francisco "would likely delay the (bridge construction) schedule by a minimum of eight to 15 months and increase the project costs by tens of millions of dollars." A Corps spokesman was quoted by the media as stating, "We confirmed Caltrans' findings."