The Mile High Skyscraper
“This is The Illinois, gentlemen,” Frank Lloyd Wright announced to reporters in 1956, unveiling the renderings of a mile-high skyscraper. “In it, will be consolidated all government offices now scattered around Chicago,” the architect said. It was going to be the world’s tallest structure, by a lot. He planned it four times higher than the then-tallest building, the Empire State Building — “a mouse by comparison,” he noted.
Wright raised both attention and eyebrows for his visionary proposal. He had no client, no site, and no budget. But the revered architect clearly had the credentials and experience. He had started his career as the protégé of the Louis Sullivan, “the father of skyscrapers,” and, at 89-years old, had designed hundreds of celebrated buildings. Was the Mile High a real possibility, or was it the hubris of the man who once identified himself in court as “the world’s greatest living architect”?
As outrageous as the may project have seemed, it wasn’t just a quick scribble. Wright revealed a rendering that matched the scale of his vision, one of them as tall as 22-feet, towering over the architect. He elaborated on the details of his massive “Sky-City,” proposing landing pads for 100 helicopters and parking spaces for 15,000 cars. He had spread elevator banks through to building to ensure the timely evacuation of the building’s 100,000 occupants within only one hour. He had specified the 528-story building to be served by 76 “atomic-powered” elevators, each capable of racing up 60 miles per hours.
Despite Wright’s reputation, later recognized by the American Institute of Architects as “the greatest American architect of all time,” no one dared to build the project. But although the Mile High skyscraper did not come to fruition during Wright’s days, we may see one in ours. In 1996, only four buildings were considered “supertall,” classified by the Council of Tall Buildings and Urban Habitats as a tower exceeding three hundred meters (984 feet). Today, there are more than a hundred, with about a dozen completed every year— each taller than the Empire State Building. The Burj Khalifa, the current tallest building on earth, stands twice the size of the Empire State Building, and measures more than half a mile. The Jeddah is planned to complete in 2020 at a full kilometer-length, about two thirds of a mile. The new target may very soon be the whole mile.
Even the sheer scale of Wright’s building is well within the realm of today’s possibilities. Wright proposed 18,460,000 square feet of space, roughly 30 football fields crammed in one tower. That’s no longer record-breaking. In 2008, Dubai completed its new airport terminal that’s about the same size, includes a hotel, mall, and several lounges all under one roof, and handles 85,000 people a day. Five years later, the Chinese city of Chengdu constructed a building that's even bigger, and perhaps inconceivable even for someone like Wright: New Century Global Center, a shopping paradise with offices, conference rooms, several hotels, an ice skating rink, a Mediterranean village and an artificial beach enlivened by a 500-feet long screen displaying sunrises and sunsets.
What exactly was stopping us from putting up these megastructure 70 years ago, and why are we building them today? It wasn’t for Wright’s design. Surprisingly, both the Jeddah and the Burj Khalifa resemble Wright’s vision. The towers have a footprint shaped like a tripod that gradually gets smaller and tapers to a spire, giving it a silhouette of a minaret. Wright himself had explained the virtue of this shape. “It is really a steeple and has no wind pressure at the top… it is the surest form of resistance of outside pressure from the side because every pressure on every side is felt by the other two sides and resisted by them altogether.” The Illinois, as implausible as it may have seemed back then, made structural sense.
Wright himself thought his project was technologically feasible using the technology of his time. After all, it was the time of the Space Race, the year the first satellite, the Sputnik, was shot into space. Yet, his project faced substantial technological challenges. Even though he picked reinforced concrete, the same material of the Burj Khalifa, 1950s concrete could only withstand compression of 20 megapascals (MPa), enough to support a 20-story structure. While Wright sought to compensate this in his design with a more stable, buttressed core structure, engineers doubt it would work. But today, breakthrough inventions make concrete stronger than ever. The addition of water-reducing polymers has increased concrete’s compression strength, allowing higher buildings without thicker walls, as in the Burj Khalifa’s 80 MPa concrete structure, a good 163-stories tall. The latest “ultra-high-performance” concrete mixes in steel-fibers and exceeds 150 MPa, possibly reaching up to 250 MPa. As one engineer puts it, “This concrete is not your grandpa’s cement and stone and water.”
But even with today’s sophisticated concrete blends, the constraints of Wright’s age went beyond materials alone, and lay deep inside the Mile High’s very core — the elevator core. To circulate all the buildings’ occupants with an average elevator of the time, traveling at normal speed, would require so many elevator banks, there would be virtually no room left for anything else. Wright sought to overcome the lift’s limitations with nuclear power. Like other post-war Americans, he was enthralled by the atomic optimism of the time, which made it seem inevitable that everyone would soon all drive cars powered by a small nuclear reactor, like the Ford Nucleon concept car. Today’s elevators are still powered by electricity; yet, they are lighter, bigger, and move faster across thinner cables, capable of moving 45 miles per hour— compare to the Chrysler Building’s initial 10 miles per hour. Elevator cabins can even be stacked to create “double-deckers,” doubling the capacity per elevator-shaft. They are also more efficiently run with traffic management algorithms that study usage patterns and optimize the grouping of passengers as they go to different floors, reducing the time for people to reach their destination. The latest development is to run elevator cabins along magnetic rails, avoiding friction, like a Maglev train. The humble elevator, once a steam-powered platform to hoist coal in mines, has been quite the trailblazer.
But even with all the technology of today’s age, Wright’s project would face insurmountable hurdles. For instance, the 15,000 car-parking spaces would take up about 5 million square feet. Parking would eat up almost a third of his entire building — and storing stationary cars is not quite the most economic use of skyscrapers. At the same time, postwar Americans, Wright himself included, preferred the horizontal city, not the vertical city. They escaped dense downtowns for greener pastures, the suburbs, with their single-family homes and office parks. As successful as Wright was as an architect, his Mile High was a stretch too far. But all the headwinds facing Wright’s “Sky-City” then, are blowing very different directions today.
The Era of the Supertall
Most civilizations have an innate desire to reach towards the sky, to build the world’s biggest buildings, like the Ancient Egyptians built Pyramids. Architects gladly oblige, following their utopian calling to build the perfect world, with a superior shape, in a flawless structure. But each society has its constraints. Wright’s tower fought technological limitations and suburbanization. Shukhov’s faced resource scarcity. Only rarely do all forces align that enable a society to construct unprecedented buildings. When they do, it is a golden age, like when De Medici’s built the Renaissance palaces in Florence. Or when back in the 12th century families rivaled for the tallest home in San Gimignano, eventually leading to tower-houses, 72 of them, some up to 70 meters tall. Now, we are witnessing another golden age; but not of palazzos or casa torres. This time around, we are living in the era of the supertall.
The advent of supertall buildings is a result of a convergence of three trends: the acceleration of technological progress, unprecedented urbanization, and investments in infrastructure. The first is the most obvious. Technology has always been an important factor allowing for very large buildings. It was the invention of the elevator that led to the skyscraper. Then structural steel enabled builders to stack more floors on top of other, upon which air-conditioning allowed the ventilation of these higher floors. These days, occupancy sensing distribute conditioned air and electric light more efficiently. Machine-aided manufacturing enable designers to bypass blueprints and communicate directly with machines, allowing higher forms, such as curvilinear shapes optimized to reduce wind vortexes that the supertalls create. Sometimes, the devil is in the details. The height of a skyscraper can be dependent on something as peculiar as the track system that hang the carts of window cleaners.
If technology is the seed, then today’s “urban renaissance” is the fertile soil that grows the megastructure. The twenty-first century is an urban century, with for the first time more than half of the world’s population people living in cities, attracted by the many and diverse opportunities of urban life. But when the influx of city residents exceeds the growth of urban areas, higher land prices occur. Here the benefits of the megastructure kick it. Since it maximizes the number of people on a given plot of land, it can offset the exorbitant land cost. Meanwhile, it makes for more compact and dense urban living, allowing for more connections between people, which in turn can stimulate economic growth. Since cities excel in many ways from economic output to the number of patents per capita, some entire countries have decided to base their national policy on the relationship between urbanization and economic growth, like China. It has added roughly half a billion people to its cities, and today has the largest amount of supertall buildings. Some governments go as far to do all this in the desert, like Dubai, its growth driven not by oil, but by real estate — the mantra of build it and they will come, as the Burj Khalifa shows. But skyscrapers are altering cities worldwide. For three centuries, the skyline London was defined by St Paul’s Cathedral, with its silhouette of a dome and spires. Then, the taller skyscrapers came in, crowding the skyline with ingenious shapes that earned them their nicknames, including the Gherkin, Walkie-Talkie, and Cheesegrate.
The third factor that explains the era of the megastructure is the large roll-out of transit infrastructure, helping to irrigate buildings with an incessant and efficient stream of people flows. The same year Wright proposed his Sky-City, the United States signed the Federal-Aid Highway Act, leading to the construction of 41,000 miles of interstate highways. But private cars have their limitations, since they take up a lot of space — a car driving under 20 miles per hour already takes up thirty times as much space as a pedestrian. The roads needed to feed the tower with occupants and the spaces required to park their cars would turn much of his Mile-High City in a parking-skyscraper standing in a spaghetti of highway flyovers. In contrast, mass transit, such as trains, subways, or even shared vehicles, carry more people more efficiently, giving megastructures access to a larger pool of users. Not surprisingly, the Burj Khalifa sits on a rapid transit station, the Dubai’s second busiest metro station. The Canton tower too has a stop on Guangzhou’s subway network, a city with the greatest subway ridership after New York. But just as buildings benefit from infrastructure, the reverse is also true. Transit developers are starting to see the real estate potential of their stations, capitalizing on the passenger trips that they generate. Airports and train stations are increasingly not just places to pass through to get on a train or flight, but places to do business and to stay the night. What was once just a piece of infrastructure, is becoming a destination.
These three trends are accelerating. Automation, the internet of things, and artificial intelligence are the new technological frontier, helping achieve faster construction times, bigger operational efficiencies, and easier maintenance of massive buildings. The world increases to urbanize, particularly as millennials chose to live in cities and developing nations in Africa and Asia seek to grow their economies through cities. Transit investments in Asia continue and is about to revolutionize worldwide, thanks to the benefits of the sharing economy and the self-driving vehicle. All of this could lead to even bigger buildings.
Our society is fundamentally different since Wright proposed his mile-high tower. What were once considered impossible ideas have become architectural opportunities. Today it may just be a matter of time until one building goes the extra mile.