How do you dismantle an 80-year-old bridge?
In the case of the old eastern span of the Bay Bridge, which opened in November 1936 and closed Wednesday night, the answer is that it requires “very careful thought and safe thought,” Caltrans chief bridge engineer Brian Maroney said today.
With the new eastern span set to open by early Tuesday morning, Caltrans is now focusing on demolishing the old span, a process that will take about three years and cost about $240 million.
Workers will have to take particular care in dismantling the 1,400-foot-long cantilever section because it’s tight “like a bow and arrow” and contains “a lot of energy,” Maroney said.
Releasing all that tension and energy has to be done “thoughtfully and carefully,” he said.
Taking reporters on a tour of the old eastern span on Thursday, about 16 hours after it closed, Maroney said, “I have very strong feelings for this old bridge” and admitted he’s more excited about the process of taking it down than he is about the process of building the new span.
“I’m a nerdy engineer,” he explained.
Maroney said the old bridge was state-of-the-art for its time but also was the product of the Depression because money was tight so it doesn’t have any unnecessary frills.
“It’s an honest structure with a pure design and there no metal that’s unnecessary,” he said.
On the other hand, people “didn’t worry about earthquakes” during the depression and worker safety wasn’t as high a priority then as it is now, Maroney said.
He said more than two dozen workers died while building the original Bay Bridge but no one has been killed during the construction of the new span and Caltrans wants to maintain that record while the old span is being taken down.
“One of our goals is not to have anyone die,” Maroney said.
The old span is being replaced because a piece of its upper deck dropped onto the lower travel lane in the 1989 Loma Prieta earthquake and one person died. The new eastern span is designed to be much safer during earthquakes.
Bay Bridge spokesman Andrew Gordon said the first part of the demolition work will be performed by a joint venture of California Engineering Contractors, Inc. and Silverado Contractors, Inc. at a cost of $93.7 million.
The joint venture will take down the cantilever section, the temporary detour near Yerba Buena Island known as the S-curve and tie-in structures to the east and west sections of the old span, Gordon said.
Contracts for the additional demolition work to take down the road decks and the foundations will be put out for bid later, he said.
By next March people will notice big parts of the old span coming down and most of the steel will be taken down by the end of 2014, Gordon said.
Maroney said “environmental stewardship” is an important component aspect of the demolition effort and the steel on the old span can be recycled.
Maroney also said some of the old bridge pieces will be preserved for historic purposes at the Oakland Museum of California.
Jeff Shuttleworth, Bay City News