New San Francisco Bay Bridge taking shape
2,047-foot-long, $6.3 billion structure will be the longest self-anchored suspension bridge in the world.
Caltrans reached another milestone in the $6.3 billion replacement of the Bay Bridge's east span Wednesday when a giant crane lifted into place the first permanent piece of the self-anchored suspension span — a road deck section weighing more than 1,000 tons.
In a Kodak moment for bridge historians, the crane hoisted the 90-foot by 84-foot deck section off a barge and lifted it more than 120 feet in the air for placement on temporary supports.
Early in the afternoon, crews began sliding the deck section on rails for a half-day journey 650 feet to the west to its permanent spot over Yerba Buena Island.
This section is the first and westernmost piece of the suspension span deck that motorists will drive on when the new Bay Bridge east span between Oakland and Yerba Buena Island is finished in 2013 or 2014.
"This is a huge milestone for the Bay Bridge project," Caltrans spokesman Bart Ney said Wednesday morning aboard a boat, giving media members a closer view of the operation. "This is the first real permanent part of the self-anchored suspension bridge to be put into place."
The crane — the biggest construction crane on the West Coast — took about two hours to lift the bridge deck to just above temporary bridge supports.
Construction workers then checked and rechecked the giant load to make sure it was positioned just right on a big cradle used to slide it on rails into place.
"They're going to go very slowly and carefully to make sure they get the alignment just right," Ney said. "Whenever you do something the first time, there is a challenge. There will be a learning curve. We're going to take the entire day to get this first piece into place."
The bridge deck section was one of eight delivered to the Bay Area on Jan. 21 — more than a year late because of welding problems at a manufacturing plant in Shanghai.
The other seven sections will be placed the same way, hoisted off barges on the Bay, lifted onto temporary supports, then pushed by rail into place over Yerba Buena Island or shallow Bay waters just off the shoreline.
Twenty larger bridge deck sections will arrive from China later this year. Because they go in a section over deep Bay waters, they can be lifted directly in place by the barge crane.
The suspension span is considered the sleekest and most showy element of the new eastern span. Unlike flatter and lower portions of the new span, the suspension span will have a giant cable looping over a 525-feet-high tower, matching the height of the towers on the Bay Bridge's west span between Yerba Buena Island and San Francisco.
At 2,047 feet long, it will be the longest self-anchored suspension bridge in the world, Caltrans said.
"The suspension span is the signature part of our new east span," Ney said.
Traditional suspension bridges have twin cables anchored to separate structures located on the ground. This span's single giant cable will be anchored to the eastern end of the suspension bridge.
Source: Contra Costa Times
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