ForConstructionPros.com

Bigge Crane & Rigging, San Leandro, CA, a firm specializing in heavy lifting applications, has installed the second of a pair of 2,000-ton steel bridge deck sections on the new San Francisco Oakland Bay Bridge. The second mega-lift operation completes the transition spans between the concrete Skyway bridge on the Oakland side and a suspension bridge (not yet built) to Yerba Buena Island.

The first transition span, carrying the eastbound carriageway, was lifted into place overnight in early February. The second span, which will carry westbound traffic, also took just 10 hours to lift in an overnight operation in late August.

"To lift a 2,000-ton load that is 200 ft. long and 85 ft. wide to a height of 200 ft. is an operation that requires precise engineering and thorough planning," says Weston Settlemier, president of Bigge Crane & Rigging. "To do it twice is something special for us."

Prior to each lift, the transition span section, or "tub", was loaded onto barges for transport from Portland, OR, where it had been fabricated. With bridge piers, erection towers and other obstacles, there was no space to bring a barge in at the correct angle under the bridge. As such, Bigge loaded each tub onto the barge using 48 axle lines of Scheuerle self-propelled modular trailer (SPMT). The SPMT enabled Bigge to rotate the tub by the necessary 90°.

Each tub was raised to a height of approximately 200 ft. within tolerances of 1/32 of an inch. To move such a heavy weight so precisely, Bigge used computer-controlled Hydrospex strand jacks.