Lights Illuminate Bay Bridge East Span Progress

Magical and uplifting. Those words describe the atmosphere on San Francisco Bay at dusk last night as lights outlining the new Bay Bridge East Span catwalks came on for the first time, to whoops of appreciation by reporters, bridge staff and other onlookers strategically perched at Treasure Island in watchful anticipation. At exactly 7:45 p.m., as darkness was falling on a relatively clear, late-summer day on the Bay, the construction lights strung along the bright orange catwalks for the main cable of the new bridge’s signature self-anchored suspension span (SAS) were switched on, giving a hint of how the bridge might appear in profile on future Bay Area evenings once it opens in 2013.

The fluorescent catwalk lights will be used during remaining construction activities on the SAS and its main cable at night and in heavy fog. Crews erected the four orange catwalks this summer in preparation for the placement of the main cable, which will begin in early 2012. The catwalks on the east side of the East Span’s iconic tower are 1,060 feet long and start at a five-degree angle near the deck and gradually reach a 28 degree angle closer to the tower. The catwalks on the west side are 600 feet long, and start at a much steeper angle of 24 degrees, reaching 35 degrees at the top of the tower. The 12-foot-wide wire mesh catwalks are positioned four feet below the eventual location of the main cable, giving the Bay Area a preview of the SAS’ graceful, curved profile.

Meanwhile, in another construction milestone, the four last deck sections for the SAS arrived at the Port of Oakland early Sunday morning, signaling the end of fabrication work in Shanghai and the imminent closing of the gap in the bridge’s twin, side-by-side decks. Two of the newly arrived deck sections will occupy a pivotal place in the innovative bridge, the mid-Bay juncture where the steel SAS will meet the already completed concrete Skyway portion of the bridge, and where the SAS’ main, nearly mile-long cable will anchor into the twin road decks.

The span’s single, main cable will be anchored into the east end of the roadway, and travel up and over the single tower to wrap around the west end of the twin decks before traveling back over the tower to anchor back into the east end. — Brenda Kahn