The urgency to accommodate urban population growth is requiring many cities to increase their residential density.
This in turn threatens to reduce the availability of publicly accessible open space in the core urban areas of our cities. As cities start running out of areas to designate for future parks, creating new public open space on-structure can become an economically viable option for meeting the needs of new communities living and working in these denser urban environments.
Building landscapes on-structure itself is not a new idea. However, the scale and complexity of recent examples of new urban landscapes are truly awe-inspiring. They are beautiful and well-loved urban parks and are even more exceptional when we understand how they have emerged through the combined imagination and expertise of architects, landscape architects, engineers and the building industry.
One of the first significant parks built over a highway, and which set the benchmark for this typology of landscape architecture, is Freeway Park in Seattle by Lawrence Halprin+Associates. It opened in 1976 and sits above Interstate 5, and it proved to many that there was true community and aesthetic value in the air-space over our urban infrastructure.
In the past 10 to 15 years, we have seen an increasing number of outstanding examples where cities have taken this opportunity to build up and over operating transport and service infrastructure. These innovative projects continue the Halprin example of adding essential urban greenspace for nearby communities. They have not only changed the landscape of the cities in which they’re located, but also point to innovative ways that cities are now considering how and where to create parks and open space to serve urban residents when open space is no longer available.
Three contemporary projects that demonstrate this potential are the Madrid Rio project, the Olympic Sculpture Park in Seattle, and the site of the emerging Hudson Yards development in New York City.
The Madrid Rio project
The Madrid Rio project transformed a 10-kilometre section of the Manzanares River into 120 hectares of new public open space in the centre of Madrid, and re-established the cross-city links that had been severed by construction in the 1970s of a motorway along the river corridor.
Six kilometres of six-lane motorway was reconstructed in a tunnel below the open space corridor.
The master plan for Madrid Rio was generated through an international design competition won by the Dutch landscape architecture and urban design firm West 8, in collaboration with three Spanish architectural firms. Completed in 2011, the Madrid Rio is the largest urban infrastructure project of its kind in recent European history.
Besides the remarkable feat of engineering associated with lowering the motorway below ground to create public open space above, the project reflects a unique cultural attitude that acknowledges the social role of public space. Writing in the New York Times, architecture critic Michael Kimmelman noted that the Madrid Rio project “arises from a political culture which assumes that the public service is an end in itself.”
The project is a reminder of the social and political nature of large scale urban projects around the world.
Some 30 kilometres of pedestrian and cycle paths produce a strong sense of flow and movement along the open space corridor and connect the Madrid Rio to a regional cycle path network. The largest single component is the Parque de Arganzuela, a 23-hectare parkland incorporating a diversity of recreation opportunities and cultural values.
The public open space above the motorway not only provides a vast range of recreation opportunities but also reconnects a large residential area to the historic centre of Madrid. Residents of the high-rise buildings that formerly overlooked the motorway, with its noise and air pollution impacts, now have a view over one of the most attractive public open spaces in Madrid.
Olympic Sculpture Park
The Olympic Sculpture Park is the Seattle Art Museum’s extraordinary 3.6-hectare outdoor sculpture garden which opened in 2007. Up until the 1970s, the site was occupied by the operations of Unocal, the oil and gas corporation, and the remaining transport infrastructure.
With the departure of the industry, the Seattle Art Museum proposed to transform the contaminated brownfield into a new green space connecting downtown Seattle with the waterfront of Elliott Bay in Puget Sound.
Weiss/Manfredi Architects designed the sculpture park in collaboration with Charles Anderson Landscape Architecture. The Z-shaped configuration of tilting landforms cleverly results in a directed but meandering pedestrian experience as visitors pass through the portal of the Museum’s foyer or enter the site freely from the streetscape.
Reconnecting the site to the waterfront was the major challenge as they were separated by a motorway and major railway line. The solution was to construct a sloping landbridge over the transport corridor that forms part of the outdoor sculpture museum. The connections between the museum building and waterfront are both physical and visual.
This project demonstrates how the challenge of creatively extending the urban fabric up and over infrastructure resulted in a dynamic and aesthetically compelling new urban destination. By inventing what the architects call a “hybrid landform” the project has delivered an exciting new pedestrian-focused infrastructure and welcome greenspace, connecting the city to a revitalised waterfront.
Hudson Yards Development
The capacity of New York City to continue to create new public open space - and new kinds of greenspace - is inspirational. The Hudson Yards project is an 11.5-hectare development being carried out on a deck over a working rail yard, and including three rail tunnels and the new Gateway Tunnel. The site comprises air space over a working railway yard with 30 active train tracks. It represents the largest private real estate development in the history of the United States.
Thousands of new residents, workers, and daily visitors will use the site. The development’s Public Square and Gardens, 5.6 hectares in size, were designed by Nelson Byrd Woltz Landscape Architects, who refer to these spaces as the “living room of the West Side.” Constructing these landscape features on the deck over working train tracks presented a challenge for soil, irrigation and planting strategies. For example, a special cooling system had to be designed to protect plant roots from the heat generated by trains below and summer heat above.
The Hudson Yards Project is a bold development, but it’s not a stand-alone development. It links into two other major urban landscape interventions on Manhattan’s west side: the widely celebrated High Line, which forms a loop wrapping around the Western Yard and providing an elevated landscaped walkway running south to Chelsea and the Meatpacking District; and a network of green spaces extending north to 42nd Street; and a connection to the Hudson River Park, which runs for eight kilometres along the riverfront, and attracts 17 million visitors annually.
Making space for new urban parks for the ever increased urban inhabitants of our cities has obviously been done before and it continues to occur. When one views the aerial maps of many of our most densely populated cities through this lens of underutilised tracts of infrastructure, the future opportunities for more of the same, be it up, over or under, are endless.