The Bay Bridge, the main east-west corridor in the Bay area, is a critical transportation link, providing a route for some 280,000 vehicles each day between San Francisco and Oakland. The traffic volume is the heaviest of any toll bridge in the country, producing more than $8 million of revenue every month.

"It's the mother of all toll bridges," said Colin Jones, a spokesman for the California Department of Transportation. "Pretty much everything leads to the Bay Bridge."When the bridge was out of commission for a month after the 1989 earthquake because a 50-foot span of the upper deck had collapsed onto the lower deck, residents of the Bay area developed a new appreciation for the structure. Although the section was quickly repaired, engineers determined that the 60-year-old bridge was unlikely to withstand another major earthquake, and they began a seismic upgrade of the entire bridge.

Rather than retrofit the eastern span, a 2.1-mile stretch between Oakland and Yerba Buena Island in the middle of the Bay, however, they soon concluded that it would be better to rebuild that half of the bridge. The State Legislature authorized the California Transportation Department in 1996 to spend $1.3 billion for the endeavor, using money from state bonds, an eight-year toll increase to $2 from $1 and state gas taxes.

Since then, the design of the new bridge has become one of the most contested issues in the area, a lightning rod for a variety of social and development concerns. The stakes are high, in part because this upgrade will be the single largest construction contract in the state's his-tory, and also because residents see the redesign as an opportunity to create an enduring, compelling landmark.

The new span will be built alongside the existing bridge so that traffic disruptions will be minimal. Once construction is completed, around 2004, the original structure will be razed.

Virtually everyone wants a say in the new look of the bridge. The San Francisco Chronicle recently ran a front-page poll asking readers to choose among a few design proposals, and 7,329 readers weighed in. Each time the bridge advisory panel meets to consider a new plan, it is greeted with standing-room crowds.