SAN FRANCISCO >> Over the Golden Gate Bridge’s eight decades of existence, iron workers, welders and engineers have helped keep it updated — a job that’s never done.
The span turns 80 on Saturday and faces a host of projects in the coming years: a suicide barrier, more seismic work and a main cable access project, to name a few.
“When they built the bridge it was innovative,” bridge General Manager Denis Mulligan said this week at the Administration Building at the Toll Plaza, which sits in the shadow of the span. “Subsequently, we have carried on that tradition.”
Previously the head engineer at the span, Mulligan is a student of the history of work on the bridge, and has overseen some of the changes himself. The bridge openeed to the public on May 27, 1937.
“In the 1970s we replaced the suspender ropes, in the 1980s we replaced the deck, so we are always investing in it,” he said. “We put the movable median barrier out there recently. We are going to build the suicide barrier, so we are always investing in the bridge to meet today’s and tomorrow’s challenges so it’s ready for future generations.”
The biggest change the bridge will see is the suicide barrier, projected to be finished in January 2021. The Golden Gate Bridge board unanimously agreed in December to award the building contract to Oakland-based Shimmick/Danny’s Joint Venture. The project is expected to cost as much as $204 million.
The project involves installing the equivalent of seven football fields of netting along the 1.7-mile bridge. It will be made of stainless steel, marine-grade cable to stand up to the elements, bridge officials said. The bridge district’s barrier plan calls for a net extending 20 feet below and 20 feet from the side of the span, although it will have to be modified in certain areas because of surrounding terrain.
A seismic retrofit of the span is ongoing, with work on the center suspension segment next. It won’t be cheap. The final phase of the seismic effort is pegged between $450 million and $500 million. The bridge is considered a “lifeline” for the Bay Area, needed to reach people in potential emergencies and a key driver in the region’s economy. The segment was saved for last because it is least susceptible to collapse in a major quake, bridge officials said. But it still could see major damage in a large temblor.
In a separate project, span officials are looking at upgrades to the bridge’s seismic sensor equipment in order to receive data quicker after an earthquake. The sensor system is designed to immediately record data that can be shared regionally, while helping engineers make the structure better able to absorb future earthquakes.
The district is also looking at a main cable access project at a cost of $13.2 million. The work requires the replacement of the existing hand ropes and the construction and installation of eight specialized main cable access travelers. That allows crews to make repairs to the span. The existing system is at the end of its useful life.
Bridge officials are also preparing plans to improve physical security at the south tower pier and south approach area. At a more mundane level, the bridge will see a fresh coat of asphalt near the toll plaza this fall, a $3.5 million project. The year’s winter rains left the area filled with potholes.
“You got to keep moving forward on the bridge,” said Dietrich Stroeh, president of the bridge board, who lives in Novato. “Especially as technology changes. You have to keep moving with it.”
He paused and remarked on the span’s 80 years.
“You are part of tradition,” he said. “People here are very innovative to keep it all moving forward. There is no rest.”
