BAY AREA
Bridge construction crews do some very heavy lifting
1,750-ton steel transition span is new structure's largest hunk yet

In the middle of the bay, between Yerba Buena Island and Oakland, the biggest single piece so far of the new Bay Bridge is being slipped into place.

At 1 a.m. Tuesday, construction crews began the laborious process of lifting into place a 1,750-ton piece of steel that will eventually connect the long, concrete skyway to the steel single-tower suspension span.

"This is a major milestone for the east span," said Bart Ney, a Caltrans spokesman.

The lift is the biggest in Caltrans history, Ney said. A slightly smaller steel section -- the transition span for the eastbound skyway -- was raised into place in February. Temporary towers will continue to help support the steel transition spans for five or six years until they can be joined to the suspension span.

The work is unrelated to this weekend's closure of the Bay Bridge's lower, eastbound deck. On the San Francisco end of the bridge, crews are replacing the western approach, a $429 million project. During the closure, which begins just before midnight Friday, crews will demolish parts of the existing bridge approach. The closure lasts until 5 a.m. Tuesday.

The steel transition span lifted Tuesday reaches 200 feet out over the bay and was built in Vancouver, Wash. A barge called the Lucky Logger shipped the piece to the construction site.

Using strand jacks mounted on the skyway and on two 175-foot temporary lifting towers, the piece was raised 150 feet into the air over 11 hours. Crews will slide two temporary support towers beneath the span and connect it to the towers and the skyway.

From start to finish, the work is expected to take about 40 hours, probably ending tonight.

At that point, the skyway section of the bridge will be 94 percent finished. The skyway -- 1.4 miles of elevated concrete viaducts -- is expected to be completed by the end of 2007, but the single-tower suspension span it will eventually connect with won't be done until 2013.

The new eastern span, which will cost an estimated $5.4 billion, is being built to replace the existing span, which was fractured in the 1989 Loma Prieta earthquake and is considered seismically unsafe.

More information on both projects is available at www.baybridgeinfo.org.

BAY BRIDGE CONSTRUCTION: WHAT'S BEEN DONE AND WHAT'S TO COME

The length of the entire new eastern span will be 2.2 miles

Western approach replacement

Under construction. Eastbound lanes closed Labor Day weekend for partial demolition.

Estimated completion: 2009

Western span

Seismic retrofit completed 2004

Yerba Buena Island transition span

Work not yet started.

Estimated completion: 2013

Single-tower suspension span

Contract awarded in March 2006.

Estimated completion: 2013

Skyway

Work 94% complete.

Estimated completion: Dec. 2007

Oakland touchdown

Work not yet started.

Estimated completion: 2013

Source: Caltrans

The Chronicle