It’s been a busy few months for the new East Span of the Bay Bridge.
A pair of 600-foot-long catwalks stretch from the East Span tower down to the road decks below. Bill Hall, Caltrans
By Craig Raphael
Published: August, 2011
It’s been a busy few months for the new East Span of the Bay Bridge.
In late May workers successfully hoisted the world’s largest cable saddle atop the self-anchored-suspension (SAS) portion of the span. With a flat base and curved top, the 450-ton cable saddle is engineered so that the nearly mile-long single cable can pass over the tower twice.
Unlike traditional suspension bridges, the cable of an SAS bridge anchors into the roadway, rather than the ground. Starting at the bridge’s eastern end, the cable will travel up and over the saddle to wrap around the west end before traveling back up and over the tower to anchor into the east end again.
The structural elements of the main tower are now complete with the saddle in place. Just shy of its 525-foot apex, the signature tower will be crowned with a decorative head once the cable is installed early next year.
In a sign of further progress, orange catwalks have been erected to help workers install the bridge cable safely. Two 600-foot-long catwalks are currently on the Yerba Buena Island side of the tower and will be followed by additional catwalks on the opposite side later this summer.
Workers travel up and down the catwalks using harnesses to make preparations for cable installation. Soon they will build a frame to support the weight of the cable while it is being installed. The frame will also help guide placement of the cable, which will be strung just above the catwalk.
Workers use great caution as they traverse the catwalks, which are placed at a steep 35-degree angle at their highest point. Made out of wire mesh panels, the catwalks may look delicate, but they actually weigh 16.5 tons each!
The new East Span is on track for completion in late 2013. The bridge is a key element in a seismic upgrade program overseen by the Toll Bridge Program Oversight Committee, made up of Caltrans, the Metropolitan Transportation Commission’s Bay Area Toll Authority and the California Transportation Commission.
For more information on the new East Span of the Bay Bridge, visit baybridgeinfo.org
The “world’s largest cable saddle” is lifted to the top of the new East Span tower (left) some 500 feet above the Bay. Next, the 450-ton saddle is positioned just above the tower (right), where workers prepare to lower it into place. The signature tower will be crowned with a decorative head once the cable is installed early next year. Photos: Bill Hall, Caltrans
