Workmen wielding welders and grinders Thursday clambered about the collection of steel cylinders connected by thick steel plates, oxidized to a reddish brown from a month at sea.
Their job: detach the section of the new Bay Bridge from the barge that had carried it from its birthplace in Corpus Christi, Texas, through the Panama Canal and up to the Caltrans construction dock in Oakland.
Once free, the 85-by-73-foot footing box, which is 21 feet tall, will float on its barge between the twin hulls of a catamaran barge and be lifted up like a very large marionette. After floating over to Yerba Buena Island, cables will lower the structure onto 13,200-foot piles set into holes drilled 100 feet into bedrock and concrete.
"We're boasting a little bit today because we're finishing the foundation," said Bart Ney, Bay Bridge seismic retrofit program spokesman for Caltrans, the state's transportation agency. Once contractor Keiwit/
FCI/Manson lowers the big box onto the piles, the box will sit half in, half out of the water.
Over the next month, a concrete pier will be poured into a steel frame on top of the box, and a pier will be ready for the tower, and the bulk of KFM's $178 million foundation contract will be completed, Ney said.
The milestone is especially significant because work stopped when Bay Area leaders and Gov. Arnold Schwarzenegger battled over funding for the exotic structure. The governor threatened to substitute a much cheaper concrete viaduct, which would have required a different foundation, but Bay Area leaders agreed in 2005 to fund the suspension span with the additional $1 toll on state-owned area bridges that began in January.
The new bridge isn't expected to open fully to traffic until 2013.
KFM is also the contractor for the $1 billion, 1.2-mile skyway segment of the new bridge, which now has all of its precast concrete sections in place and is expected to be finished in about a year.
As soon as the skyway is completed, motorists crossing the 1936 eastern bridge will see the new suspension span begin to take shape. Then building partnership American Bridge and Fluor Enterprises, awarded the $1.43 billion contract for the 1,854-foot-long bridge, will begin hoisting sections of the tower and assembling its four conjoined legs. Those steel sections are now being fabricated by Chinese steel company ZPMC on an island off Shanghai.
"Each of these legs could stand as a tower on its own," Ney said, which provides redundancy needed in a major earthquake.
A single cable will eventually run from one end of the span's deck, up to the tower, loop around the other end of the deck, return to the top of the tower and attach at the same end of the deck where it began. Rather than having a massive concrete anchorage, like a traditional suspension bridge, the cable is anchored to its own decks.
In addition to Texas and China, other parts of the world will also contribute parts of the bridge, such as Japan and Britain, where the "saddles" that hold the cables will be constructed.
Caltrans is rebuilding the eastern Bay Bridge from Yerba Buena Island to Oakland because the 71-year-old steel cantilever bridge was found to be unable to withstand a major earthquake. The 1989 Loma Prieta earthquake shook loose a section of the bridge's upper deck, killing a motorist.
The earthquake spurred an $8.7 billion effort to strengthen all of the area's bridges against future quakes up to 8 magnitude. The landmark western double suspension span was retrofitted at a cost of $304 million.
Contact Erik Nelson at email@example.com or (510) 208-6410. Read his Capricious Commuter blog at InsideBayArea.com.