World’s Largest Cable Saddle Placed Atop Longest Self-Anchored Suspension Span

Update: 

Cable Saddle Placement: A First-Hand Report and Photo Album

Update 4:45 p.m., May 19, 2011

Sporting an American flag billowing in the wind, the cable saddle had made its way roughly three-quarters up the East Span tower by 4:45 p.m. today. According to Caltrans bridge spokesman Bart Ney, the flag is meant to mark completion of the structural elements of the tower. “They will top out (the tower) today, so they put a flag on it, and a banner.” The banner sports the name of the construction consortium building the self-anchored suspension span, American Bridge/Fluor.

The operation to lift the final structural piece into place started at 6 a.m. today, with the cable saddle expected to touch down between 7 and 8 p.m. Still to come is a decorative tower head.

Thursday, May 19, 2011

The Bay Bridge East Span's Self-Anchored Suspension Span (SAS) celebrates another milestone today as workers place the world’s largest cable saddle atop the tower of what will be the world’s longest SAS, at 2,047 feet. The tower for the SAS, the signature element of the new East Span, will ultimately stand at 525 feet tall.

Strand jacks will hoist the 450-ton, steel cable saddle more than 500 feet into the air to place it onto a single steel component known as the "grillage" that was placed atop the four tower legs on April 15. This grillage will evenly distribute the weight of the cable saddle, and eventually the cable, amongst the four tower legs.

Cast in Japan (see story), the saddle will carry the SAS’ nearly mile-long single cable. Unlike traditional suspension bridges where the cables are anchored into the ground, a self-anchored suspension bridge’s cable is anchored in the road-decks. The cable will anchor into the east end of the roadway, travel up and over the tower to wrap around the west end before traveling back up and over the tower to anchor back into the east end.

According to Caltrans spokesman Bart Ney, "The 2.6-foot-wide cable will act like a giant, unbelievably strong sling."

The tower will be complete this summer when the tower head is placed. The new East Span is key element in a bridge seismic upgrade program overseen by the Toll Bridge Program Oversight Committee, made up of Caltrans, MTC's Bay Area Toll Authority and the California Transportation Commission.

For more information visit BayBridgeInfo.org/projects/sas-tower.