While most cities strive for a sustainable level of urban density, there are limitations at play that can restrict the amount of upwards growth. In Mexico City, for example, height restrictions guide the growth outwards rather than upwards, and often the preservation of historic low-rise architecture halts expansion plans. In an attempt to mine the possibilities for alternative expansion, Kurt Kohlstedt from 99% Invisible has presented a round-up of the different ways in which architecture can instead grow below the ground surface.
Real-world concerns such as the cost and logistical nightmares of large-scale excavations ground some of the following proposals, but their provocative nature is opening up the dialogue for future possibilities. Several conceptual new projects, such as a 35-story subterranean "Earthscraper" designed by BNKR Architectura and the recent "New York Horizon" proposal which won the 2016 eVolo Skyscraper competition present audacious alternatives to traditional skyscraper design.
While removing the multi-million dollar infrastructure below Central Park can understandably be deemed as a polemic response to a serious question, the notion of below ground skyscrapers is one that is gaining more and more traction. More than likely, the first to be realized will be an infill project wherein the sunk costs have already been expended, and a stable underground framework already exists for the new architecture to cling to.
As Kohlstedt explains, "large-scale underground architecture is rarely created from scratch," but rather is reincarnated through adaptive reuse projects where the excavation occurred years ago. Often taking the form of abandoned mines and silos, within these projects the below-ground void is asking to be revived with a new program. A prime example of the ways in which these subterranean spaces can provide valuable public space for a crowded city is the New York Lowline; the mimetic cousin of the famous High Line.
The recently approved Lowline will run beneath Manhattan, making use of old rail infrastructure in a similar way to the High Line. The main difference? Rather than an open-air walkway, the Lowline is comprised of a cavernous underground trolley terminal, illuminated by solar reflectors. It will be the first park of its kind in the world; the borrowed sunlight will allow plants to grow, creating an underground oasis.
Strong political connotations can often be embedded within these kinds of spaces, especially where the existing void was related to the military. But the Lowline is not the first example of an underground recreational or business zone; others include an amusement park in a mine in Romania, a wellness retreat in an old salt mine in Ukraine, and a trampoline center in an old slate mine in Wales.
Each of these projects lies in peripheral or completely rural areas, where it is currently more feasible to mine below ground. This makes the Lowline's approval a historic moment in the development of underground public space, due to its centrality in one of the world's most bustling metropolis. The unsustainable surges in the cost of real estate, coupled with advancement in construction methodology will undoubtedly result in many more spaces of its kind in the near future, most likely giving rise to an eventual real-life Earthscraper.
To read Kurt Kohlstedt's essay in full, head to the 99% Invisible Website.
News via 99% Invisible.