Presidio Tunnel Tops – THE DIRT

Presidio Tunnel Tops / Rachel Styer, courtesy of Partnership for the Presidio (Presidio Trust, NPS, and Golden Gate National Parks Conservancy)

In 1989, the Loma Prieta earthquake damaged the Doyle Drive Bridge in the north end of San Francisco, which moved vehicles through the Presidio to the Golden Gate Bridge since the 1930s. As a result, California’s department of transportation (Caltrans) embarked on a planning effort to re-engineer the roadways and interchanges through the Presidio. During those discussions in the 1990s, landscape architect Michael Painter, designer of the parkway system within the 1,500-acre Presidio, offered a plan for replacing the viaduct, which had severed the upper areas of the Presidio from Crissy Field, with tunnels. His idea was that with tunnels, the city could then use the space on top for a new park. More than thirty years later, James Corner Field Operations has realized this vision with Presidio Tunnel Tops, a 14-acre park designed for kids and their families.

Presidio Tunnel Tops / James Corner Field Operations, courtesy of Partnership for the Presidio (Presidio Trust, NPS, and Golden Gate National Parks Conservancy)

According to Richard Kennedy, ASLA, principal-in-charge and head of the San Francisco office of Field Operations, Caltrans had offered to form the soil from the tunnel excavation and other landscape work into a flat top and a triangular edge. But the Presidio Trust, the National Park Service, the Golden Gate Park National Parks Conservancy, and Field Operations had other ideas. They would rather sculpt the land. “We decided to create a topographical design,” Kennedy said, eventually using more than 90,000 cubic yards of soil. And in order to do this, they first had to look deep underground.

Presidio Tunnel Tops / James Corner Field Operations, courtesy of Partnership for the Presidio (Presidio Trust, NPS, and Golden Gate National Parks Conservancy)

Given San Francisco is an active seismic area, the Presidio Parkway tunnels, which were completed in 2012, had to be engineered for stability. This meant the rest of the adjacent Tunnel Tops landscape, a project that started in 2014, also needed to be engineered in a similar way. “That way, in the event of another earthquake, everything would move as a contiguous system with no differential settlement,” Kennedy said.

MKA, a Seattle-based engineering firm, set the tunnel park on 40-foot-deep stone columns arranged in a 10 by 10-foot grid. Each column, comprised of gravel, is 3 feet in diameter. This complex subterranean work isn’t apparent on the surface of the park, but for Kennedy it shows that the park is also infrastructure, and that infrastructure investment is needed for landscape architects to realize their vision.

“It’s a new vision for this area of ​​the Presidio — open public parkland. Before, the perception was the Presidio was a kind of commercial office park. Our goal was to invite the public in with disarming and sometimes obvious elements. On opening day, there were over two thousand children in the playground,” Kennedy said.

Presidio Tunnel Tops / James Corner Field Operations, courtesy of Partnership for the Presidio (Presidio Trust, NPS, and Golden Gate National Parks Conservancy)

Field Operations organized Tunnel Tops into three landscape zones. The first zone is a “platform,” a flat landscape on top of the tunnels at the same level of the Presidio’s main parade, which essentially acts as an extension of the historic military base.

Presidio Tunnel Tops / Ryan White, Golden Gate National Parks Conservancy courtesy of Partnership for the Presidio (Presidio Trust, NPS, and Golden Gate National Parks Conservancy)

“We purposefully designed it as a platform to leverage the incredible panorama. This elevation of 40 feet enables visitors to turn 360 degrees and see everything — from Marin to the Golden Gate Bridge, to Alcatraz Island, the Presidio, and the Palace of Fine Arts. This is an experience visitors couldn’t have had when the viaduct blocked views.”

Presidio Tunnel Tops / Rachel Styer, courtesy of Partnership for the Presidio (Presidio Trust, NPS, and Golden Gate National Parks Conservancy)

The second landscape zone is what Field Operations calls the Cliff Walk, a set of trails and gathering places that intentionally focus visitors on landmarks at vantage points. “We used the slope to a great extent. As visitors wind through the trail, their body position moves, so they see different elements of the horizon. It’s surprising, awesome, and highlights the drama of being on the edge,” Kennedy said.

Along this edge are charismatic benches made of cypress trees that had been culled from the Presidio. Kennedy said Field Operations had hoped for sculpting a large piece of driftwood but no such trunk large enough appeared on the park coastline (another was found and used in the playground). Instead the benches are sculptured out of 9.5-inch wide plans and “assembled Jenga-style” into a curvature that resembles a tree. He said as cypress wood dries, it becomes metallic gray and, when it catches the light, sparkles like a silver fish. The perfect wood for a vista over the Bay.

Presidio Tunnel Tops / Rachel Styer, courtesy of Partnership for the Presidio (Presidio Trust, NPS, and Golden Gate National Parks Conservancy)

The Outpost, an interactive play landscape, is the third zone. It’s where most visitors may enter Tunnel Tops, off of Mason Street, which bisects the upper area of ​​the Presidio and Crissy Field. Other draws here include the new Crissy Field Center and adjacent Field Station, two environmental learning centers designed by architecture firm EHDD that will teach kids about anthropology and ecology. This area is “designed to appeal to a broader of families,” Kennedy said.

Presidio Tunnel Tops / Rachel Styer, courtesy of Partnership for the Presidio (Presidio Trust, NPS, and Golden Gate National Parks Conservancy)

Given the upper portion of Tunnel Tops needed to be flat and highlight the panorama, Field Operations could use the lower portions nestled in the slope to add more intricacy without obstructing views.

Custom play elements are designed to bring children into the vistas. For example, there is a gap in the Outpost’s climbing wall on axis with Golden Gate Bridge. “Moments like this can create positive memories and life-long connections to the outdoors,” Kennedy argued.

Presidio Tunnel Tops / Rachel Styer, courtesy of Partnership for the Presidio (Presidio Trust, NPS, and Golden Gate National Parks Conservancy)

The Outpost is also designed so that as the plants grow in overtime, the playground will feel more like the marshlands of Crissy Fields. The same plant species are found in the play area. “Labyrinthine trails will form, adding a layer of mystery.”

Play elements extend east from the Crissy Field Center creating an inclusive environment for toddlers to preteen children. The elements escalate in complexity as children move outwards from the buildings.

Near the Field Center, there are simple play areas comprised of sand and water for the youngest children. Older children can then enjoy a tunnel through a large driftwood trunk, which lets them to burrow through or climb above, along with slides set in boulders.

Presidio Tunnel Tops / Rachel Styer, courtesy of Partnership for the Presidio (Presidio Trust, NPS, and Golden Gate National Parks Conservancy)
Presidio Tunnel Tops / Rachel Styer, courtesy of Partnership for the Presidio (Presidio Trust, NPS, and Golden Gate National Parks Conservancy)

The bird’s nest sculpture, which is modeled after an oriole’s teardrop nest, enables children to climb on the outside and perch at the top, or climb from inside the nest and poke their head out like small birds.

Presidio Tunnel Tops / Rachel Styer, courtesy of Partnership for the Presidio (Presidio Trust, NPS, and Golden Gate National Parks Conservancy)

The most complex element is the forest den, which is a pile of logs. The interior of the structure has a small room filled with ropes and nets. “The exterior of the pile is purposefully challenging to climb and was designed to provide a sense of risk graduated. I have watched as some children became very nervous as they climb further towards the top. While the children can play safely, they can experience challenges, which also challenges themselves. I have seen children form teams. It asks them to be more brave,” Kennedy said.

Presidio Tunnel Tops / Rachel Styer, courtesy of Partnership for the Presidio (Presidio Trust, NPS, and Golden Gate National Parks Conservancy)

On opening weekend Kennedy also saw teenagers climbing to the top of the logs to experience the view. For them, Field Operations has also designed seating areas that will eventually be enshrouded in marshes.

The new park includes over 200,000 plants of 200 varieties, many of which support birds and pollinators. Approximately 50 percent are native and drought-tolerant plants, chosen for what the climate will be in a few decades. The native plants were grown from seed in a nearby Presidio nursery to ensure they are “genetically specific to this landscape,” Kennedy said. The Presidio Trust “invested in plant communities that will last and can coexist with existing natural resources in the national park.”

The upper level landscape, which is connected with the manufactured military landscape of the Presidio, offers Mediterranean plants from countries like Chile and South Africa that will better blend with the existing non-native cypress and eucalyptus trees and gardens. In the Cliff Walk and Outpost areas, Field Operations focused on incorporating 100 percent native plants.

Presidio Tunnel Tops was made possible by a number of organizations. The Presidio Trust, a non-profit organization, has a mandate to preserve the historic military base and has restored 150 acres of landscape to date. The Presidio in turn is part of the 80,000-acre Golden Gate National Recreation Area, managed by the National Park Service, the country’s largest urban national park. The Golden Gate National Parks Conservancy is the non-profit arm of the park and raised $98 million of the $118 million project, while the Presidio Trust provided the other $20 million.

The Tunnel Tops is just one part of a broader revitalization of the Presidio. CMG Landscape Architecture, a San Francisco-based firm, is creating a plan to update Crissy Field, the beloved landmark designed by HargreavesJones in the 1980s.

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