At dawn this morning, workers began slowly lifting the first 2.3 million pound, 525-foot section of the new Bay Bridge tower into place.
The first of 20 steel tower sections for the San Francisco-Oakland Bay Bridge's Self-Anchored Suspension Span (SAS) is being lowered onto a marine foundation where it will be bolted to concrete and steel piles that reach 196 feet below waterline into the bedrock.
This one steel tower, which weighs 1,200 tons, more than 2.3 million pounds, will be one of four legs that will come together, tapering towards the top, to form the one tower of the Self-Anchored Suspension Span.
Sheer link beams connecting each of the tower's fours legs are designed to flex independently, absorbing seismic energy during an earthquake and protecting the bridge from catastrophic damage.
San Francisco Mayor Gavin Newsom said the Eastern Span's Self-Anchored Suspension Span is the largest public works project in California's history and stressed the Bay Area's importance on a national scale.
A mechanical platform, seen in the center-right of this image, called a strand jack gantry is slowly lifting the 2.3 million pound segment from its horizontal position along rails on the barge into a vertical position over the tower's foundation and will then lower the sections into the marine foundation mounted in the bedrock.
Oakland Mayor Ron Dellums was on hand to praise the work being done on the Oakland side of the San Francisco-Oakland Bay Bridge.
Design and style played a notable roll in the final choice of the bridge. The more iconic and impressive one-tower Self-Anchored Suspension Span is meant to rival the celebrity of the Golden Gate Bridge just across the Bay. The Golden State Warriors basketball team, based in Oakland, has already incorporated the under-construction bridge into their new logo.
The tower sections, which are manufactured in China, are the first shipment of 20 sections that make up the four individual tower legs. Three more will be anchored to rods in the foundation over the next three weeks, and the next sections arrive here in October.
The steel section installed Wednesday was shipped to San Francisco from sister city Shanghai on June 18 on its month-long voyage to Pier 7 at the Port of Oakland.
Unlike a typical suspension bridge that has two cables running end-to-end with the roadway suspended from these main cable, this single-cable design is anchored within the eastern end of the roadway, and the cable is carried over this single tower and wraps around the two side-by-side decks at the western end.
A strand jack gantry positioned atop the erection tower will lift the top of the tower segment, while a winch-assisted tipping cart will stabilize the segment and help move it down the rails. The tower section will pivot from a horizontal to a vertical position. The strand jack gantry will then lift the segment off the barge and into position onto the foundation 196 feet below the water.