FOUR MILLION POUNDS OF STEEL HOISTED IN PRE-HOLIDAY CONSTRUCTION

Published: January, 2011 

Latest Sections Bring East Span Tower Three-Quarters of the Way to Final 525

Foot Height

The holidays came early for the San Francisco-Oakland Bay Bridge when the third tier of tower sections for the self-anchored suspension span (SAS) were placed during a round-the-clock operation mid-month. Crews from contractor American Bridge/Fluor started the operation on December 15, a day earlier than planned in a race against a series of forecast rainstorms, and completed the four million pound lift in just over 106 hours, beating their best schedule predictions.

The SAS tower is actually comprised of four individual legs (photo 1), each of which is made up of five vertical sections, or lifts. This third lift contained four legs that are 102 feet tall and weigh 1.1 million pounds (or 551 tons) each. With these sections in place, the tower now stands 374 feet tall — 40 feet above the high-point of Yerba Buena Island, and nearly three-quarters of the way toward its final height of 525 feet. It is already taller than Coit Tower (210 feet), the Campanile at U.C. Berkeley (307 feet) and the Tribune Tower (310 feet).When completed, the SAS will take its well-deserved place on the list of Bay Area landmarks.

The painstaking lifting process involved tilting each leg from horizontal to vertical on a specially-designed barge positioned at the tower’s base (photo 2), and then hoisting the legs over 400 feet into the air — using a lifting system known as a strand jack — so that each segment could be moved into the rust-red erection tower and lowered into place (photo 4). Once each leg was set down, crews bolted the third and second legs together using splice plates (photos 3 and 5).

Fabricated at the Zhenhua Heavy Industry Company in Shanghai, the tower will help give the bridge its unique design, with a single cable draping over the iconic tower. Crews placed the first tower sections onto the foundation in July 2010, and the second set in October 2010. The arrival of the final group of tower sections is expected in February 2011.

Meanwhile, the SAS road decks have been taking shape since February, with 18 deck sections — nine eastbound and nine westbound — already in place (photo 6). Two more steel deck sections arrived from China with the third tower lift in December, and will be erected by the project’s massive red, white and blue crane in the coming weeks. To date, crews have installed over half of the 28  sections that will make up the SAS deck when the bridge opens in 2013.