Current Topics

New Bay Bridge East Span
Construction Goes Vertical

July 29, 2010… The painstaking and precisely choreographed installation of the first steel tower section of the new San Francisco-Oakland Bay Bridge’s self-anchored suspension span (SAS) concluded successfully last night at 7:20 p.m. – 14 hours after the operation began in the predawn hours on Wednesday.

Officials Gather to Celebrate Milestone Event

Yesterday, with the operation still in full swing, an oft-empty parking lot on Treasure Island was transformed into a bustling press conference as mayors, state and local officials, curious onlookers and others gathered at midday to celebrate the placement of the 1,200-ton steel tower shaft.

“This is yet another impressive engineering and construction milestone in what has been an ongoing seismic retrofit project here in the Bay Area,” said California Business, Transportation and Housing Agency Secretary Dale Bonner. “This is one of the country’s most vital bridges.”

Joining Secretary Bonner to recognize this construction milestone were San Francisco Mayor Gavin Newsom, Oakland Mayor Ron Dellums, Bay Area Toll Authority (BATA) Chair Scott Haggerty, California Transportation Commission Chair Bob Alvarado, and American Bridge/Fluor Project Director Mike Flowers. A surprise guest was Golden State Warriors’ own new tower David Lee, an NBA all-star, who brought caps adorned with the team’s new logo, which features the SAS.

“We are building a bridge that will not only establish a new standard of engineering excellence and seismic safety, but also provide a beautiful landmark,” said Haggerty. “The Golden State Warriors have adopted our landmark, and I’m very proud of that. The bridge is already being seen as an icon that represents the Bay Area to the rest of the world.”

Iconic Tower Begins to Rise From Bay

When completed, the 525-foot tower will help give the bridge its unique design, which calls for a single cable to anchor into one side of the span’s eastern end, drape over the tower, wrap around the west end, and go back over the tower to anchor back into the eastern end. Fabricated at the Zhenhua Heavy Industry Company (ZPMC) in Shanghai, the tower is made up of four individual steel legs, each of which is made up of five vertical sections, or lifts. The first installment of tower segments – four lower-level pieces that are each 165-feet-tall and weigh 1,200 tons – arrived in the Bay Area on July 9. Once these tower segments are in place, cross bracings and shear link beams will connect the four legs and form the portion of the tower beneath the roadways.

The operation began before first light on Wednesday, July 28, as construction crews prepared to tip and lift the tower shaft into place. The steel shaft was floated to the site near Yerba Buena Island the night before aboard a specially outfitted barge equipped with tracks and a winch-assisted cart designed to roll the segment’s base along the tracks.

Shortly after 6 a.m., a mechanical platform called a strand jack gantry atop the erection tower – over 200 feet above the waterline – began to lift the top of the tower segment. To keep the barge steady while accommodating the shifting weight of the tower leg, over 270,000 gallons of ballast water were pumped from one side of the barge to the other through interior bulkheads. The tower leg reached vertical after nearly five hours of tipping, allowing crews to detach the pin assembly connecting it to the barge, suspend it from the strand jack gantry, and slowly move it into place above the tower foundation.

After nearly four hours of lateral movement, the tower leg was carefully positioned over rods and dowels in the massive foundation, a concrete-encased steel footing box, and gently lowered into place. The three remaining base tower sections will be placed in the coming weeks, and then workers will attach the tower legs’ cross bracings and shear link beams. The second lift of tower sections is scheduled to arrive in the Bay Area in early autumn.

“This is a world-class structure. There is nothing like it in the United States of America. One could argue there is no tower like this anywhere in the world,” said San Francisco Mayor Gavin Newsom. “This is something we’ll be very proud of for generations to come.”

The East Span project is being overseen by the Toll Bridge Program Oversight Committee (TBPOC), made up of MTC’s BATA, Caltrans and the California Transportation Commission.

---

Previously:

• Photos: Unloading First SAS Tower Sections
  July 2010
• First East Span Tower Sections Arrive in the Bay Area
  July 9, 2010
• First SAS Tower Sections Set Sail For Bay Area
  June 28, 2010
• Historic Lift of First Self-Anchored Suspension Span Section for New Bay Bridge
  February 2010