A sleeker, safer Bay Bridge made its debut Monday night, the culmination of a much-delayed $6.4 billion construction project to upgrade the eastern span of the Bay Area's most important artery.
Eastbound drivers emerging from the Yerba Buena Island tunnel on the new side-by-side span that replaced the 77-year-old double-decker steel-truss section will be treated to sweeping views of the Oakland skyline.
At 2.2 miles, including a 1,263-foot central span, it is the world's longest self-anchored suspension bridge, a structure supported by giant cables that attach to the ends of the bridge instead of the ground.
The cable itself weighs more than 5,000 tons. End to end, the cable's 137 2.5-inch steel strands stretch 118 miles, about the distance from Santa Rosa to San Jose.
The elegant, white, 525-foot central tower will soon become a Bay Area landmark like the burnt-orange towers of the Golden Gate Bridge, said Stephen Mahin, UC Berkeley professor of civil engineering.
"It's very nice that they built something iconic," he said. "There were proposals to build a causeway like the San Mateo bridge. That would look pretty boring. Now there is something everyone can be proud of."
The new bridge is also one of the safest in the world, built to withstand the strongest earthquake expected in a 1,500-year period. Bridge engineers do not cite Richter scale magnitude, but they say the new bridge would hold up in an event like the October 1989 quake, which collapsed part of the old bridge and prompted the replacement.
Engineering features such as hinge-pipe beams, expansion joints, shear keys and a foundation driven 340 feet into the bedrock beneath San Francisco Bay will allow the bridge to rock and sway -- but not snap -- in an earthquake.
"It is certainly a lot safer than the one it replaces, which was built before we knew about earthquakes," Mahin said. "Now there's a much greater understanding about what earthquakes in the Bay Area can do."
The project has been fraught with delays and cost overruns. In 1998, the Caltrans engineers who designed the new eastern span estimated it would cost $1.3 billion. When construction began in 2002 after years of political bickering, the estimated cost had doubled to $2.6 billion and the project was supposed to be completed by 2007.