The old double-decker cantilever structure was closed in September and replaced by the new self-anchored suspension span. Since June, when the contractor prioritized completing the new eastern span, demolition has fallen six months behind.
In order to dismantle the cantilever section by spring 2016 as originally planned, the Toll Bridge Program Oversight Committee authorized millions in spending on additional crews and equipment to remove both sides of the cantilever simultaneously, instead of doing the western half first followed by the eastern half.
A major step toward dismantling the old span will happen within a week when crews cut through the steel at the middle of the cantilever section, officials announced Monday morning.
Getting back on schedule is critical, Bay Bridge spokesman Andrew Gordon said.
“Slippage of schedule has potential for a domino effect,” he said, “Especially with moving other contracts back and into environmentally sensitive periods, which would then lead to a further domino effect and delay those more.”
Despite the $12.67 million increase, the demolition is expected to stay within $300 million and not boost the overall $6.4 billion budget. Costs escalate with delays, said Brian Maroney, Caltrans’ chief bridge design engineer, so the contract increase is “a really clever trick … almost like a freebie.”
The demolition work on the old span, including holes on the cantilever, was clearly visible from a boat during a media tour of the construction site Monday. Already, 1,400 feet of upper deck and 600 feet of lower deck have been removed.
The removal of the steel structure includes work to keep the bridge from collapsing. Crews with California Engineering Contractors and Silverado Contractors have had to neutralize the stresses and pull the suspended span on each end outward to prevent it from falling inward. Hydraulic jacks have been installed to restrain the suspension span and keep force at the midpoint at a minimum. Skilled crew members will torch through the steel, Maroney said.
“You cut this side first, then that side, then this side. You don’t just cut through,” he said. “The last member will be an eyebar. That will be about a 10-minute cut.”
Even when the crews start cutting apart the old span, it won’t be visible to the public for roughly another month when entire panels come down.
“This is the big deal,” said Caltrans senior resident engineer Bill Howe. “This is the biggest part of the demolition because the bridge is now coming apart and it is the point where the two cantilever ends are now free.”
Removing the old cantilever section is just one part of dismantling g the old span. There are two other sections of the bridge, and the contract for the removal of those pieces is expected to go out to bid in July.
There are also underwater foundations — a bid for the removal of those is expected to be advertised in late 2014 — that may be imploded with explosives.
“I believe it actually goes faster, saves money,” Maroney said. “We’re not done doing that evaluation but it appears it may be the least environmentally impacting alternative because we get in and get out quickly.”