F E AT U R E By Elizabeth Reynolds
Underground Urbanism
Stitching together the layers of our urban landscapes
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Landscaped spaces are often placed above buried infrastructure. Elizabeth Reynolds asks if landscape practice can become an integral part of the design process. 1. Coppenhill – an urban ski slope above a biomass waste to energy plant in Copenhagen, Denmark designed by Bjarke Ingles Group with landscape by SLA. © Creative Commons (Kallerna, 04 November 2019)
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s our cities grow up, out and down, it is time we better understood how the different layers of these complex urban environments relate to one another. Landscape architects have an important role to play in stitching cities together in a manner that optimises land while also ensuring that the journey of a pedestrian through a city is a coherent and enjoyable one. The notion of multi-level living is something which as humans we have had to adapt to. In his book Vertical, Stephen Graham asks difficult questions about the potential consequences for people living in dense, multi layered cities. For example, do citizens have a right to identify and experience natural ground level? Although people tend to experience underground places as interiors, cities such as Hong Kong and Singapore are developing more underground pedestrian walkways, and the same care should be taken to
design these as coherent sequences within longer journeys as with external spaces. Beyond the human element, it is worth also considering the natural systems disrupted by construction of the infrastructure needs of cities. Earth extracted for railway networks, utility pipes and basements is relocated and used, for example, to contour golf courses or reclaim land from the sea. The properties of that soil are therefore lost from the city, and the water previously held within it either extracted or diverted. What physical space and natural capital remains beneath our cities, and how can we balance the competing demands and consequences associated with urban development?
Overcoming urban severance Since Le Corbusier’s vision of the Radiant City in the 1920s, a desire to create fast flowing elevated roads
has scarred many cities. At street level, even contemporary road and rail projects designed to improve access and over long distances tend to create severance that impedes local connectivity. When considering the removal or scaling back of major road infrastructure, careful consideration should be given as to whether it is most appropriate to make lateral or vertical changes, such as new (deep) tunnels, shallow (cut and cover) decks or (elevated) bridges. These decisions will largely depend on the surrounding street pattern and built form; subsurface constraints (such as utility diversions or ground conditions that could increase construction costs) and wider policy objectives. Although sinking road traffic into tunnels can create opportunities for landscaped public open space, it is important that these initiatives are taken as part of holistic measures to reduce car use, in order to ensure that air quality and other traffic impacts are not simply displaced. 39
