Start by reading Part I: Understanding Green Infrastructure here.

Grey to Green: Replacing Moribund Infrastructure

While animals were previously thought to need exceedingly naturalistic environments in which to flourish, they have been found to repurpose human-made landscapes for their own uses. When Austin, Texas doubled the lanes of a bridge in its downtown in the 1980s, a bat colony took up its home in the narrow space between the concrete spans, attracted to their warmth and the soothing vibrations of passing motorists. Originally, the bats were disliked, often because they were associated with disease and the occult. After a public information campaign, Austinites warmed to the bats and they have since become one of the city’s tourist attractions, departing their ‘cave’ between the bridges in a large plume at sundown, often with a crowd of onlookers watching their flight.

While animals were previously thought to need exceedingly naturalistic environments in which to flourish, they have been found to repurpose human-made landscapes for their own uses.

Bats aren’t the only ones who make use of grey infrastructure’s nooks and crannies. The decaying, yet secluded, pockets of infrastructure left behind by industry’s decline—such as abandoned switching stations, hulking gasometers, and vacant warehouses—became unlikely havens for nonconformist subcultures during the 1970s and 1980s. The reclamation of these ‘dead’ spaces was one of the few bright spots in the otherwise painful process of deindustrialisation. Detroit’s shuttered auto factories gave rise to dance parties and a new type of music: techno, a genre that borrows from the whirrs and pops of the shop floor. Other old factories were turned into art and performance spaces, allowing for large scale installation art and sculpture. These venues often went by names that riffed on their past uses, such as Amsterdam’s Melkweg (Milky Way), a one-time dairy factory.

Liminal spaces on the fringes of the city offered rare opportunities for exploration of identity and free expression away from the constraints of mainstream society—one of the reasons why rusting piers and old railroad trellises attracted LGBTQ+ communities at a time when they still faced widespread discrimination. However, this seclusion was not to last. Middle class professionals, raised in the bland suburbs of the 1950s, sought excitement and diversity in inner city neighbourhoods, beginning processes of both revitalisation and gentrification. The ‘festivalisation’ of urban leisure spaces, like river walks and shopping precincts, that started in the 1970s proved successful, and developers began to look towards former industrial precincts to create housing and to concentrate retail. Many of the first experiments in the reuse of industrial spaces were unsanctioned and led by squatters, but they were quickly replaced by large consortiums and urban redevelopment authorities. Critics, particularly in capital cities with high land values, have bemoaned the fact that these conversions had a sameness to them, and areas that once had texture and individuality were being ‘mall-ified’, using culture as a vehicle to promote consumption. Lower Manhattan’s lofts—unpartitioned storage spaces for dry goods—morphed into ‘the loft as aesthetic’, an idealisation of the industrial form that drew on nostalgia for what the sociologist Sharon Zukin calls “genuine and hand-made” things of the past. Zukin’s writing on the loft’s transformation from cast-off to urbane buzzword, implores architects and developers to actually reuse buildings and not to merely hint at ‘industrial chic’ through new-builds that employ exposed brick and ‘loft style’ floor plans create an ‘urban vibe’.

In this sense, grey-to-green projects exemplify adaptive reuse that also acknowledges ecological processes already under way.

In this sense, grey-to-green projects exemplify adaptive reuse that also acknowledges ecological processes already under way. At industrial sites no longer in active use, trees had sprouted from cracks in paved lots and vines had climbed across girders. In the 1970s, New York’s High Line, an elevated rail line once used to transport cows from middle American states to meatpacking plants in Lower Manhattan, bloomed with wildflowers in springtime, to the delight of trespassers who used it as a gay cruising ground. The ‘stagflation’ of that era meant huge shortfalls in municipal coffers, and park maintenance was one of the areas in which jobs were cut. Inadvertently, many parks began to take on a more ‘natural’ appearance. Some saw unkempt parks as a blight that, like graffiti, symbolised social decline, but others were more sanguine and appreciated the ‘greening’ taking place. Indeed, in places like West Germany greening was something of an aspirational practice, and untamed spaces took on new symbolic meaning as realms of healing and regeneration in the aftermath of war and destruction. German society has been home to a reverence for the natural world since at least the time of Romanticism and was fertile ground for the environmental movement of the 1970s. The rise of environmentalism dramatically changed conceptions of urbanised nature and paved the way for a green infrastructure approach.

The idea that old, rusting industrial infrastructure held value, and might be reused to promote green aims, is linked partially to the role of artists in shaping conversations around reuse. Two movements in particular, Land Art and the New Topographics, posited a way to appreciate hulking post-industrial structures, which they saw as human-altered landscapes that were nonetheless part and parcel of nature. The photographs of Bernd and Hilla Becher—straightforward depictions of water towers, blast furnaces, and gas tanks—were particularly influential, and helped the public appreciate the stark beauty and sculptural forms left behind by industry. The Bechers’ inspiration came largely from Germany’s Ruhr Valley, where small cities, industrial landscape, and greenswards are mixed together. Starting in the 1990s, a network of improved ‘landscape parks’ connected cities and showcased modern ruins like smokestacks and coking plants. This ‘environmental reclamation’ made use of the structures as both architectural follies within larger parks and, less frequently, stabilised them and repurposed them as art halls and community centres.

Two movements in particular, Land Art and the New Topographics, posited a way to appreciate hulking post-industrial structures, which they saw as human-altered landscapes that were nonetheless part and parcel of nature.

While the New York’s High Line has become the go-to example of reusing moribund infrastructure as green cultural space, it is one node in an ongoing lineage of green urbanist projects. Well before the development of the High Line—a ‘linear’ park that has both enamoured built environment practitioners and become infamous for catalysing a real estate bonanza—there was Paris’s Promenade Plantée, the world’s first elevated park, which opened in 1993. Linking the Bastille to the Bois de Vincennes, it directs pedestrians from the city centre into a large, open green space. The idea of such linear parks goes back to the late 19^th century, particularly to the work of Olmsted and his sons, on projects like Boston’s ‘Emerald Necklace’ and Atlanta’s Druid Hills Park. Promenade Plantée benefited from the fact that it was elevated well above street level, meaning that no land had to be acquired and the columns on which it sat, designed to support locomotives, could bear the weight of planter beds and full-grown trees. What’s more, the elevated position gave users a sense of discovery, even Parisians who passed under the Promenade daily could delight in the revelation of a new perspective over the city.

In the 15 years between the opening of the Promenade Plantée and the ribbon cutting for the first phase of the High Line, a number of other conversion projects took place. These lesser praised works of landscape architecture and urban design help to show the variety of scales at which grey-to-green conversion can occur, these include Manchester’s Castlefield Viaduct, Chicago’s Bloomingdale Trail, Seoul’s Cheonggyecheon Stream Trail, and Amsterdam’s Westergasfabriek. These conversions became sites for recreation and culture, with a green sensibility. The wild success of the High Line, and the neighbourhood change it precipitated, has led some to call out all grey-to-green projects as harbingers of gentrification, advocating instead for ‘just-green-enough’ parks that hold back on frills, or promote alternative forms of greening. The rapid change in the areas surrounding the High Line is perhaps indicative of changes that have happened in all global cities, where land values have skyrocketed in recent years. Access to supplemental funding from developers has allowed some projects to grow in scale, but, in cities with less financial acumen, locally based grey-to-green projects have come alive at a fraction of the High Line’s cost, using ingenuity and the labour of community members.

In Berlin, the reclamation of Tempelhofer Feld—the municipal airport made famous by the Berlin Airlift—has become a symbol for a less-is-more ethos in the creation of green space. Closed since 2008, the airport was slated for redevelopment with a variety of plans put forward, including an exclusive health centre and an artificial mountain. Ultimately, a referendum placed a complete ban on construction, leaving the field as one of Europe’s largest grasslands. Tempelhofer Feld is now on the itinerary for picnicking tourists and cyclists, but also for dozens of migratory bird species.

Nearby Tempelhofer Feld one can find the Natur-Park Südgelände, an 18-hectare park that runs along a former railway switching yard. The yard once served Anhalter Bahnhof, but after the station was severely damaged during World War Two and taken out of service the Südgelände languished. Like so many redundant spaces in the divided city it became overgrown. Grass and tree seeds, including black locust trees, an invasive species from North America, flew into the space and took root along the old tracks. Plans to develop Südgelände as a light industrial space went through years of revisions, eventually coming to a complete standstill. In 1995, Deutsche Bahn donated the site to the City of Berlin, and a park was officially opened in 1999. Rather than remove invasive species, Grün Berlin (the site’s managers) let them stay. They also left industrial fragments in situ, including a 50-metre-tall water tower, a railway wheelhouse, and a massive locomotive. The artist group Odious produced welded sculptures and metal pathways that snake over and around these forms, reinterpreting them as sculpture. In recent years, a family of foxes has taken up residence between a stand of trees and a stretch of rail line. On some days, walkers can see the small groups of sheep employed by Grün Berlin to chew back tall grasses.

In some cases, like the High Line, these repurposed industrial landscapes have become wildly popular destinations that threaten to overshadow their initial artistic and ecological aims.

Greening projects have creatively reused old industrial sites by transforming abandoned factories, railyards, and other derelict spaces into vibrant public parks and green corridors. In some cases, like the High Line, these repurposed industrial landscapes have become wildly popular destinations that threaten to overshadow their initial artistic and ecological aims. However, in many other cities, these projects have more subtly redefined grey infrastructure as green space, weaving together spaces that speak to both the industrial past and a more eco-sensitive future.

Urban to Rural Corridors

Green spaces have worked in tandem with, and as a barrier to, urban development. Many greenswards and greenbelts were laid out by planning authorities as urban growth boundaries, starting in the late 19th century. The idealised notion of green that animated the idea of greenbelts also facilitated the development of lawn-based low-density suburbs. At the start, suburban developments were, like parks, seen as a healthful way to bring nature into the lives of those living in cities, but the rapacious suburban development that began after the Second World War has isolated cities from areas of primary vegetation and locked inner neighbourhoods into a paved ring that, in large cities, is often 40 to 50 kilometres wide. While green amenities initially made suburban living more attractive to cramped-up apartment dwellers, they also contributed to the outward expansion of cities into surrounding rural areas. Today, developed countries face a real threat from uncontrolled sprawl, not just because they disconnect cities, and their residents, from the countryside, but also because of the rate at which sprawl gobbles up grasslands, wetlands, and pastures.

While green amenities initially made suburban living more attractive to cramped-up apartment dwellers, they also contributed to the outward expansion of cities into surrounding rural areas.

Developing intertwined urban and rural landscapes will be crucial to mitigating climate change, ensuring adequate food supply with minimal shipping time, and providing for recreation for city-dwellers, now the majority of the earth’s residents and growing still. Cities also need to be permeable for flora and fauna, especially migrating species like birds and insects. With this in mind, many have advocated for greenspace networks that wrap around, and wind through urban areas. Imagining these networks as ‘infrastructure’ has helped hasten their construction and has given their proponents an advocacy tool. As the theorist Lauren Berlant said of infrastructure, it is “another way of talking about mediation—but always as a material process of binding, never merely as a material technology…or norm that achieves something.” Wildlife corridors help to reconnect human settlement with landscapes imagined as ‘natural’, or as less interfered with by human hands. This process also helps to make areas where people live more resilient, protecting them from the urban heat island effect, from flooding, and from soil erosion.

One thing that urban to rural corridors are explicitly not is suburbs. Housing developments in suburban areas are sometimes named with a suffixes that imply a high degree of greenness, such as -gardens, -park, or -estate; but in reality auto-dependant suburbs often fail to provide for a diversity of plants and animals and their heavily-managed landscapes are often dependent on chemical sprays, fertiliser, and constant mowing. In order for urban-to-rural, or urban-to-wild, corridors to be successful they need to dispense with some of the thinking that brought about suburbs and start to imagine a new kind of ‘green’ that goes beyond the chlorophyl colour and starts to take into account the ways plants and people interact.

In reality, auto-dependant suburbs often fail to provide for a diversity of plants and animals.

The concept of a detached home with a small front lawn originated in the U.K. with the Garden City, begun by the urban planner Ebenezer Howard, who envisioned self-contained communities surrounded by greenbelts, combining the benefits of town and countryside. Freestanding houses nestled into lawns and manicured hedges could be accessed by two transport technologies that were relatively new in the early 1900s: the streetcar and bicycle. These modes of transport allowed homes to sprawl out further, and reoriented housing towards to include a front, and often rear, lawn or garden. While the wide mansion front had been a sign of distinction in past eras, new houses turned away from the street. Garden Cities used generous green spaces, parks, and natural landscapes as key selling points to attract middle-class homebuyers seeking a more tranquil and healthier environment away from congested urban centres, but still with access to big city jobs and amenities.

Howard’s vision of dispersed, rationally planned estates was, at the outset, a rejection of capitalist housing provision and an endorsement of cooperatively managed communities, very much in keeping with the utopian socialism of the late-19th century. The economist Henry George, who advocated for a progressive land tax, and the futurist novelist Edward Bellamy both influence Howard’s planning philosophy. Howard’s treatise on Garden Cities, first published as To-Morrow: A Peaceful Path to Real Reform (published in 1898), echoes Looking Backward: 2000–1887, in which a Rip-Van-Winkle-like character falls asleep in 1888 and awakes in the U.S. of the year 2000, which has been transformed into a socialist utopia. However, the utopia promised by garden cities failed to take root, in part because the streetcar and the bicycle were quickly replaced by cars. As early as the 1930s, planners saw that suburbs with low densities and high automobile use might be a problem. Not just because of the environmental degradation of cheaply built homes with septic tanks (that reckoning would come later with environmentalism of the Silent Spring generation in the early 1960s), but because of what automobility did to the rest of the city. Motorists sped through city streets, turning them into death traps for pedestrians. The speed demon became a common trope in literature of the period, including Sinclair Lewis’s Babbitt and F. Scott Fitzgerald’s The Great Gatsby, in which a crash between the estates of East Egg, Long Island and the working-class tenements of Queens plays a major plot role.

Rather than try to balance the needs of the (at the time) small number of car owners with the many—public transport users and pedestrians—U.S. cities radically replanned their streets around the needs of motorists.

Automobile traffic and the deaths of children playing the street were major issues in the Inter War period in the United States. Rather than try to balance the needs of the (at the time) small number of car owners with the many—public transport users and pedestrians—U.S. cities radically replanned their streets around the needs of motorists. This only accelerated in the Post-War Era when car ownership became the norm, and large swathes of cities were levelled to build highway interchanges and to provide surface parking to suburban commuters. While sprawl-related problems might be a North American trope, they have, over the course of the last five decades, become global issues as countries around the world embrace the U.S.-style automobility. Ironically, private vehicles (tellingly called “leisure cars” at their outset) have been positioned as the best way to explore nature. Generations of city dwellers have been implored to grab their keys to “go for a ride in country”, where they can feel the sun and wind on their face (but can be spared from the rain or the hassle of walking. Indeed, many car companies used Native American names and the names of swift-footed animals to establish a connection between automobiles and Indigenous cultures and landscapes. However, as discussed earlier, the cars themselves have helped to close in on the hunting grounds of big cats, starving them and, often, turning them into roadkill.

As the countryside was crisscrossed by fast-moving roads, it became harder and harder to explore it without a car. Reflecting on the meandering walks he took through Britain in the 1930s, Laurie Lee lamented that a “shaggy” landscape that (just twenty years before) looked as “though it had just been cropped by mammoths” has since been “bulldozed for speed.” The automobile “cut the landscape to pieces, through which the hunched-up traveller races at gutter height, seeing less than a dog in a ditch.” A major theme of the hippie and back-to-the-land movements of the 1960s and 1970s was the sullying of the landscape by cars. As Joni Mitchell sang in “Big Yellow Taxi”, “they paved paradise and put up a parking lot”. Cars, meant to unlock nature for the masses, ended up despoiling it.

Cars, meant to unlock nature for the masses, ended up despoiling it.

The U.K. was one of the first places to confront the violence of road and home building in rural areas and sought to curb the expansion of its capital city with the London Metropolitan Green Belt, which was formalised in the 1930s through a series of planning acts and policies aimed at restricting outward growth. Green belt areas were typically held in public ownership or had strict development restrictions placed on them. During the same period, groups like the Ramblers sought to assert their right to the countryside, staging mass walks of mostly urban youth to protest the enclosure of hiking grounds by private landowners. A key accomplishment of the movement was the establishment of a system of national trails. Following this example, cities around the world established accessible parklands, both as an anti-sprawl initiative and as an extension of the leisure areas provided by smaller urban parks. Linear parks that wrapped cities were developed in Ottawa, Canada and Sydney, Australia in the mid-20^th century. They provide places for citizens to commune with the environment and wildlife corridors. They have proven less effective at curbing sprawl and, in many cases, have been eaten away at by other uses. Atlanta, Georgia’s proposal to create a police training centre in the outer suburban South River Forest, dubbed ‘cop city’ by opponents, is just the most recent example of a highly politicised green belt incursion.

In the densely populated Netherlands, greenbelting has been reversed and the sparsely populated Groene Hart (Green Heart) sits in the centre of the Randstad, a megalopolis that contains most of the country’s major cities and half of its 18 million people. The Green Heart combines intensive agriculture, including an extensive greenhouse network, with nature trails, lakes, and historic towns. Protected areas like bogs, marshes, and wetlands also receive water runoff and help to protect densely populated areas from flooding, a living-with-water approach to water management that differs remarkably from traditional engineering-based practices of floor channel and culvert building. The government of the Netherlands has committed to building more parklands and trails in the Green Heart for recreation and for long-distance cycle commuting.

That said, green itself can be a tricky frame, because it is so often associated with what’s optically green, and that is bound up in northern European landscape imaginaries, and the climates of Northern Europe.

That said, green itself can be a tricky frame, because it is so often associated with what’s optically green, and that is bound up in northern European landscape imaginaries, and the climates of Northern Europe. Corridors that are biodiverse can be brown, rocky, tree-less, dusty, and emphatically not green. In many water-scare parts of the world, the enactment of ‘green’ can do real environmental harm, just think of the water-hungry golf links that cover wide tracks of land in deserts where they are climatically inappropriate. However, green infrastructure provides a valuable framework that unites multiple disciplines and constituencies.

In a recent book, the historian Dirk van Laak describes how infrastructural systems emerged in the 19th century and how they became integral to the smooth functioning of markets and society. They became closely managed by the state, and through ongoing oversight, infrastructural systems have formed “new routines, standards of conduct, and expectations”. Funding and maintaining ‘green infrastructure’ projects over traditional brick, mortar, and steel projects will require another shift in our systems, in which we increase our appreciation of the ‘ecosystem services’ provided by green spaces, and the way they improve mental health, biodiversity, and overall quality of life.

Corridors that are biodiverse can be brown, rocky, tree-less, dusty, and emphatically not green.

Creating truly green infrastructures might mean rejecting some of our received wisdom about what makes a landscape pleasing, and what makes it productive for society. The best time for action on this would have been several decades ago, but the second-best time is now. The actors capable of defining and creating green infrastructure are, as we have seen, myriad and come from the disciplines of visual art, land management, biodiversity, and public health. Investing in well-defined and ambitious green spaces also sends a message to the youth who grow up using them about what society values. Like the ‘social infrastructure’ of community centres and religious institutions, it is in urban green spaces that we encounter our neighbours and build civil society.

Samuel Holleran is an interdisciplinary artist and writer. He has worked as an art director, researcher, and educator with civically-engaged design firms, universities, and nonprofits in the U.S., Australasia, and Europe. He is currently a Postdoctoral Research Fellow in Urban Design at RMIT University in Melbourne, Australia.

*The above text was commissioned in collaboration with Stavanger municipality’s project NEBSTAR — New European Bahaus Stavanger. CAS and NEBSTAR have entered into a collaboration on a collection of texts that are part of CAS’ ongoing text series “Built Environments”. The series presents different approaches to urban development and different opinions on the design of urban landscapes. CAS has editorial freedom and editorial responsibility in this collaboration.