East Span Now Towers Over Original Bridge
The latest lift of tower sections for new East Span of the San Francisco-Oakland Bay Bridge – which will elevate the new tower more than 100 feet above the original bridge’s high point – is being installed this week by ironmen working around-the-clock until all four legs are in place, estimated for sometime on Friday, March 4.
“At about 5 a.m. this morning, our crews started lifting the first leg, which weighs almost 500 tons, over 400 feet in the air,” said Caltrans spokesman Bart Ney at a Monday morning press conference. “It is going smoothly and we already appear to be slightly ahead of schedule.”
Although appearing as a single unit from a distance, the tapering tower is made up of four individual shafts, each of which is composed of four vertical sections. The legs in this final tier are each 105.6 feet tall, and once placed will raise the tower’s height to 480 feet. The tower will top out at 525 feet later this spring when a fifth lift is raised and set in place. That final lift will crown the tower with a two-part apparatus: a steel "grillage" to connect the four shafts, topped by the tower saddle that will eventually hold the span's single main cable.
“The lifting part of this week’s operation takes longer than our other three lifts, because we’re going so high up in the air,” said Ney. “Our conservative estimate is that it will take 10 hours to lift each leg vertically, and 30 hours total for each leg to set it in place and prepare the lifting system for the next leg.”
The fourth lift of tower sections arrived in San Francisco Bay on February 14, 2011, aboard the heavily loaded Zhen Hua 18. Also on board were two large steel deck sections; splice plates, crossbeams and struts for the tower and deck sections; and 490 pieces of barrier rail and 24 segments of the span’s bike path. One of the 1,500-ton deck sections was put in place on the eastbound side of the new East Span last Friday, February 25.
“While this shipment wasn’t the largest we have received in terms of tonnage, it probably had more individual pieces on it than any other shipment of permanent material we’ll receive from China,” said Robert Kick, operations manager from contractor American Bridge/Fluor Enterprises.
The Bay Area Toll Authority (BATA) — along with Caltrans and the California Transportation Commission — is part of Toll Bridge Program Oversight Committee (TBPOC), which has been overseeing the seismic retrofit of state-owned toll bridges in the Bay Area, including the Bay Bridge. BATA is also responsible for collecting bridge tolls and funding the retrofits.
— Karin Betts
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