Crowds, weather, expensive real estate and vulnerability to climate change are prompting urban planners to turn their eye to the potential of usable spaces below street level.
From an underground park in a forgotten century-old trolley terminal in Manhattan to Mexico City’s inverted 300-meter underground pyramid -- called the Earthscraper -- architects are re-imagining spaces for people and not just infrastructure in cities of the future.
“There are real opportunities to develop underground to accommodate density for cities that are already overcrowded or growing,” said Clara Irazábal, assistant professor at the Graduate School of Architecture, Planning and Preservation at Columbia University, New York. “It can expand efficiency, reduce commuting times and improve quality of life.”
Singapore is planning a 20-hectare (49 acres) subterranean labyrinth that could house as many as 4,200 scientists and researchers in soundproof labs and data centers carved out of caves, according to JTC Corp., a property developer that commissioned a feasibility study on the project.
The city-state opened the first underground oil-storage facility in southeast Asia this month, freeing space three times the size of New York’s Grand Central Station for chemical manufacturing above ground. The project caps a 30-year effort to create a petrochemical hub. It began when officials merged seven offshore islets and then spent S$950 million ($749 million) to dig rock caverns that can hold enough liquid hydrocarbon to fill 600 Olympic-sized swimming pools.
“When we ran out of room, we looked down,” said Yeoh Keat Chuan, managing director of the Singapore Economic Development Board. “We had to find creative ways to find space.”
With a population of 5.4 million, Singapore has the same number of inhabitants as Finland packed in a fraction of the land. Its skyline is already clotted with more than 4,000 high-rises. Yet, cities studying underground development could look to the Finns, who have been doing it since they began building shelters against Russian bombardment in the 1940s.
Dubbed the daughter of the Baltic, Helsinki is surrounded by water on three sides and lies on a granite bedrock that lends itself to sturdy construction. Pasi Aarnio, a development manager at builder YIT Oyj, compared Helsinki below street level to a “Swiss cheese.” Down below, there are rail tunnel and service passages for power lines and heating, as well as 20 parking facilities and two bus stations.
There is also human life bubbling 10 meters to 20 meters below, from walkways and malls to badminton courts and a kids’ playground to an ice-hockey rink and a 50-meter swimming pool.
“It’s a whole other world down there,” Eija Kivilaakso, one of the urban planners behind a 2010 master blueprint to map underground spaces.
The city’s wastewater-treatment plant operates underground; for more than three decades, Helsinki has drawn its drinking water from Finland’s second-biggest lake, Paeijaenne, through a 75-mile long tunnel.
It doesn’t stop there. Frosty sea water is funneled via tunnels to an old bomb shelter underneath a 19th-century Christian Orthodox cathedral, where it’s used to cool the computer servers of a 2,900 square-foot data center built underneath the tourist site. Heat generated by the center, run by Telecity Group Plc, is channeled to warm about 500 homes.
A sea fortress, situated on an island 15 minutes by boat from the city’s south harbor, is reachable via a maintenance tunnel also used by ambulances.
“There are so many tunnels that finding the space below ground can be difficult,” said Aarnio. “It’s getting full to about 30 meters down. Below 30 meters, there’s more space.”
Rising Asian megacities take note: Helsinki officials are planning to divert traffic via subterranean passages for trucks serving city-center stores.
Authorities in Beijing already have something to work with, thanks to Mao Zedong. He ordered the construction of an entire second city when tensions ran high with the Russians in the late 1960s. When the much-feared nuclear blowout didn’t come to pass, the network fell into obscurity and disrepair.
Many U.S. cities, locked into a car culture, have tunnel vision when it comes to moving more of their transit, utilities and water structures below the surface, according to Nasri Munfah, head of underground projects for Kansas City-based HNTB Corp., a civil-engineering consulting firm.
“It’s a no-brainer that at the rate at which Americans are fleeing rural towns and flocking to cities, developing underground structures is the logical thing to do to make these cities bearable and sustainable,” he said.
In Montreal, where the average low temperature in January is minus 14 degrees Celsius (7 degrees Fahrenheit), there’s a 19-mile (31 kilometers) underground pedestrian network connecting 30 cinemas, 200 restaurants and almost 2,000 shops accessible via 20 outdoor exits and 10 metro stations.
It doesn’t always work as planned. In the case of Atlanta, Civil War-era underground structures that doubled as speakeasies during the Prohibition were transformed in 1969 into an entertainment district with bars like “Scarlet O’Hara” to lure people downtown. Yet the novelty soon wore off, crime came in and the “city beneath the city” instead became a costly white elephant that was put up for sale.
Humanity’s yearning to build below the ground can be traced back millenia, with the most notable ruins in modern-day Turkey across a lunar Anatolian landscape.
The archaeological complex of Derinkuyu in Cappadocia is a vast labyrinth of caves and tunnels that give a flavor of what was once, probably in the Bronze Age, an entire underground city of as many as 50,000 people with evidence of bedrooms, kitchens, chapels -- even a wine press and stable for horses.
Underground realms have captured the imagination of writers, from Jules Verne’s classic “Journey to the Center of the Earth” to the science-fiction series “City of Ember.”
One of New York’s biggest draws is the High Line, an elevated park built on 1.5 miles of disused railroad tracks running along the West Side. That inspired a Kickstarter campaign to create the Lowline, which would convert a rail site in the Lower East Side into a park using fiber-optic tubes to channel sunlight below ground. It raised more than $150,000, a third more than the target, by April 2012.
Futuristic scenarios aside, there are limits to staying cooped underground.
“People need some exposure to natural light and natural ventilation to maintain their health,” said Irazábal.
Underground is also an expensive proposition, nearly five times the cost of construction above ground, according to Amy Huanqing Li, who wrote her PhD on underground urbanization at the Ecole Polytechnique Fédérale de Lausanne, Switzerland.
Part of the reason U.S. cities are laggards in underground development is the lack of government spending at the federal, state and local levels, IBSWorld’s Diment said. Boston’s “Big Dig,” the most expensive U.S. highway initiative on record, which included the relocation of 29 miles of utility lines below ground cost almost $25 billion -- more than the Channel tunnel connecting the U.K. to France.
Money is not something Singapore -- the world’s third-richest country per capita -- has to worry about.
At the Sept. 2 opening of Jurong Rock Caverns, Prime Minister Lee Hsien Loong recounted a meeting he had with the board of Halliburton Co. two months earlier where he was asked how Singapore would expand its physical land area to accommodate the world’s biggest provider of oilfield services.
His answer: “There is a theoretical limit, but with ingenuity and determination and technology, that limit can be quite a way off.”