Evan Ducharme/special to The S.f. ExaminerCrews began dismantling the upper deck of the old eastern span of the Bay Bridge on Tuesday. The first phase of demolition is expected to take six weeks; the entire tear-down is expected to be complete by 2016.

Demolition underway on Bay Bridge old span

The Bay Bridge first opened to traffic Nov. 12, 1936. Exactly 77 years later, two red excavators pried concrete off the upper deck of the original eastern span, sending vibrations through the deserted structure.

“Today, the demolition started in earnest,” said Bay Bridge spokesman Andrew Gordon on Tuesday, standing on the upper roadway. “This is what everybody has been driving on for 77 years and now it’ll be gone in three years.”

The first phase, expected to take six weeks, entails peeling off concrete, rebar and steel floor beams on 1,400 feet of the upper deck between the two peaks of the iconic cantilever.

Once the roadway has been removed, crews will dismantle the western half of the cantilever and the S-curve through early 2015. This will clear the way for extending the bike and pedestrian path on the new span to Treasure Island by the middle of that year, and building a permanent eastbound on-ramp for vehicles.

While the upper deck was designed to hold traffic and not the span’s structural integrity, taking it apart is a calculated process, engineers say. Saws, not jackhammers, are being used to cut the concrete into small, rectangular slabs that can be easily hauled off.

“We’re not going after it with a crowbar and wrecking balls,” Gordon said. “This is surgical, all things considered, with saw cutters and excavators. It’s as clean and neat as a demolition can be.”

The more complicated and visible work starts in early 2014 — making a clean cut down the middle of the cantilever. That will require jacks to prevent the highly strung span from crumbling toward opposite ends like a bow and arrow, engineers say.

While work continues on the initial $239 million contract, a second contract to deconstruct the trusses east of the cantilever will be awarded in mid-2014 and a final contract for the underwater structure by the end of that year. If on schedule, the entire dismantling down to the mud line will be complete by the end of 2016.

Dismantling work was initially scheduled to start Nov. 6, but the contractor indicated the night before that the debris containment system was not completely in place. Having the work start on the same date as the bridge’s opening decades ago was “complete coincidence,” said Gordon.

“We feel confident they’ll be done by the end of this year and it’s on track for the big picture,” he added.

Officials don’t want to keep the structure up any longer than it needs to be.

The old span remains “very susceptible to damage” by an earthquake, which prompted authorities from the beginning to call construction of the new eastern span a race against time, Gordon explained.

“We won that race and now we’re hoping we get this down before the next big earthquake hits,” he said. “We’re still in that race against time.”Andrew GordonBay Area NewsBay Bridgedemolition

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