A Parkway in Progress: The Seismic Remake of Doyle Drive Shapes Up
This is a companion piece to Planting a Parkway: Nursery Grows Native Plants for Doyle Drive
Legend has it that landscape architect Michael Painter somehow climbed to the top of the Palace of Fine Arts several years ago and gazed down at the expansive Presidio. He knew that the seismically unsafe Doyle Drive had to go, and it was allegedly from this vantage point that the Presidio Parkway architect got the idea to “nestle the roadway into the natural setting,” said project spokesperson Molly Graham.
Crews are now well into Phase II of the Presidio Parkway Project, which began in late 2009 and will convert Doyle Drive into a lush parkway that will serve as the San Francisco approach to the Golden Gate Bridge by late 2016. The 1.6-mile segment of Route 101 extends from Broderick Street to the Golden Gate Bridge toll plaza.
Phase I of the project, finished in 2012, saw the completion of the southbound High Viaduct, the southbound Battery Tunnel and the transition of traffic onto these structures and a temporary bypass. Construction is on schedule and the northbound tunnels and High Viaduct that are the hallmarks of Phase II are taking shape.
Construction on all elements of the project is occurring simultaneously. The foundation of the northbound High Viaduct – one of the few elevated pieces of the project, and aesthetically identical to its southbound conterpart – is complete, and little columns for the low viaducts will start sprouting up in coming months. Crews are installing roofing on the Main Post Tunnels and the new Battery Tunnel to the north of the existing southbound tunnel. The tunnels are all designed to conceal the roadway and create open, green space. The Main Post Tunnels, which run underneath Halleck Street, connect the Presidio’s Main Post to the waterfront and Crissy Marsh.
The entire Presidio Parkway site will be supported in the event of an earthquake, Graham said. Crews are engaged in deep soil mixing, a process that changes the ground’s chemical composition to create stabilized, cement-reinforced earth.
The traffic shift implemented during the initial phase of construction has already improved safety. In the spring of 2012, traffic was transferred from Doyle Drive onto a temporary bypass. The eventual safety shoulders are still missing from the bi-directional High Viaducts, but the installation of a median barrier on the temporary bypass has already prevented the frequent accidents that used to plague the area, Graham said. The roadway will keep the name Doyle Drive.
The visibility of the construction encourages passersby and bus riders to provide feedback, Graham said.
“People get to see all the construction, and they’re excited about what it’s bringing to the park,” she said. “It’s a much more positive design. We love taking out freeways in San Francisco, and what we’re putting in its place is a parkway.”
Because the Presidio is a national park and, under the federal definition, everything inside of it is an archeological resource, the design had to undergo environmental scrutiny before it was approved.
Graham calls it "the most beautiful construction site in the world.”
Occasionally, crews will dig up cannon balls and other artifacts from the Presidio’s long stint as a military base. The workers are all trained in handling unexploded artillery.
The national park site is not the only unusual element of the Presidio Parkway project; Phase II is the state’s first transportation project to be financed through a public-private partnership (P3). Golden Link Concessionaire is responsible for the design and construction, as well as operations and maintenance for 30 years, reducing the cost for the state.
“The contractor has done an extraordinary job making progress,” said Leroy Saage, project manager.
Travelers should expect increased activity and traffic shifts between Highway 1 and Golden Gate Plaza beginning in May. Down the line, a weekend closure of the entire Doyle Drive will allow for the completion of the new roadway and tunnels. After a traffic shift onto the new road and structures in late 2015, the temporary detour will be removed and landscaping that incorporates many native species will be completed.
Doyle Drive was first identified as unsafe in 1955.
“It’s been a long time coming,” Graham said.
MTC allocated $80 million in bridge toll funds to the $1.045 billion Presidio Parkway Project.
— Natalie Orenstein