When the Bay Bridge opened in 1936, it was considered a marvel of modern engineering. The eastern span alone wore the distinction of the world’s then-longest cantilever bridge.
Now that the east span’s sleek new replacement is up and running, another engineering marvel will take place. Only this time, it will be taking the original span down.
“We’re taking it down 95 percent in the reverse order it was built,” said engineer Bill Howe, staring up from a boat at the east span where crews are seven months into dismantling the old span. “It makes sense because it was a complex structure to build in the first place.”
The work is about to get even more cutting edge.
In the next couple weeks, crews will begin slicing the center section of cantilever in half, dividing the span into two delicately-balanced 412-foot arms. The public will eventually notice a gap in the bridge widening over the next month.
“Three weeks later you’ll see two panels gone, that’s when you’ll see it really be visible,” Howe said. “There’ll actually be two cantilevers.”
Engineers are shifting steel beams away from the center, and using jacks to put stress on the two halves to keep them from collapsing inward. Once the bridge is in half, workers will continue taking down the steel beams.
Bridge spokesman Andrew Gordon said the Bay Bridge Toll Authority voted to spend an additional $12.6 million on the project to allow workers to take down the two sides simultaneously, hopefully putting the delayed project back on schedule.
“We believe by spending this money now to get us back on schedule, we’ll see those savings at the end,” Gordon said.
Caltrans also worried nesting birds could delay the project even more. It erected nets on the massive concrete bridge pillars to keep the birds out. The pillars are prime nesting ground for Peregrine Falcons and cormorants, Gordon said.
“Once birds get in, it’s very difficult to get the approvals and permits to physically remove them,” Gordon said. “Often you have to wait the birds out.”
The entire Bay Bridge took three years to build and cost $77 million (the price included the building of the Transbay Terminal). Demolition of the eastern span will take between three to five years at a cost of $300 million.
Proving that what goes up might be a lot harder, and expensive, to tear down.