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BAY BRIDGE -- The new Bay Bridge surpassed a herculean milestone Tuesday as engineers and contractors announced the world's longest self-anchored suspension span is officially holding its own weight.
"There is, it is fair to say, a big collective sigh of relief from all the engineers working on this project," said Metropolitan Transportation Commission Executive Director Steve Heminger, who leads one of the three agencies overseeing the $6.4 billion construction project.
"There was never any question the bridge would hold itself up. The question (was) whether when (construction crews) picked it up, would they do it right the first time or would they have to be tuning it again and again? That fear turned out to be unfounded."
This "tuning" was a highly orchestrated, three-month engineering and construction feat, where bridge builders strategically and simultaneously tightened -- via hydraulic jack -- the 200 vertical steel suspender ropes that connect the span's 28 massive deck sections to its fat, mile-long main cable.
Gradually burdened with steel and concrete weighing 35,200 tons, or 77.6 million pounds, the main cable sank 30 feet closer to the ground and stretched horizontally on each side another 16 feet, according to Caltrans.
Conversely, the hollow steel side-by-side orthotropic decks rose upward and no longer sit on the falsework trestles built to hold them during construction.
It's easy to calculate steel weights
It had never been done anywhere in the world at this scale.
Unlike a conventional suspension bridge, such as the iconic Golden Gate, where two cables are anchored on land at each end, the new self-anchored Bay Bridge has a single, looped cable anchored inside the bridge deck east of its 525-foot tower.
At best, a
The current eastern span of the Bay Bridge is seismically unsafe and the state has been in a race since the Loma Prieta earthquake to finish the new span before the next Big One strikes the Bay Area.
But if it had gone terribly wrong, the decks, cables or tower could have been severely damaged or destroyed, Caltrans engineers have said.
People working on the bridge could have been injured or killed. Caltrans, MTC and the contractor, American Bridge/Fluor Enterprises, even barred recreational boats from sailing beneath the new span for several months.
With load transfer behind them, Bay Bridge spokesman Bart Ney said the focus will shift onto the relatively mundane punch-list items:
Used for the first time on a bridge anywhere in the world, the pipe hinges consist of large steel tubes that connect the segments below the roadway surface. The hinges are designed to fail first during an earthquake -- much like an electrical fuse -- and prevent damage on the more critical decks. Repairs will be faster and help return the span to service following a temblor.
"The longest mile in any marathon is the last mile," Ney said. "That's where we are today."
Contact Lisa Vorderbrueggen at 925-945-4773, politicswithlisav.blogspot.com or Twitter.com/lvorderbrueggen.
Construction began: 2002
Length: The 1.6-mile state-owned span is actually two bridges sandwiched between complex elevated connector structures -- the 1.2 mile side-by-side skyway curves westward from Oakland toward Yerba Buena Island, where it links with the 2,047-foot self-anchored suspension span, the longest in the world.
More statistics: The suspension span's 2.6-foot-diameter main cable carries 35,200 tons of hollow steel decking; that's 77.6 million pounds or the equivalent of 6,467 male African elephants.
Cost: $6.42 billion, the largest public works project in California history.
Main construction contractors (partial list): American Bridge/Fluor Enterprises, Kiewit/FCI/Manson
Designers (partial list): T.Y. Lin/Moffatt Nichol Engineers, Donald MacDonald Architects
Opening date: Labor Day 2013
Source: Caltrans, Times research
