Have you ever wondered why the tallest skyscrapers in the world, no matter how stunningly high, are always just under 1 kilometer (0.62 miles) in height? Why has no one yet attempted to build to such extreme heights? The answer isn’t about impossibility—far from it. The engineering methods, designs, and materials required to build mile-high skyscrapers have been theoretically possible since the 1970s. However, these elements weren’t perfected until the early 2000s.

So, what are the main obstacles to building skyscrapers 1 or even 2 miles high? And what are the engineering marvels and materials that could make such colossal structures a reality? Let’s delve into the challenges and solutions of constructing the world’s tallest towers.

Obstacles and Solutions

Building a skyscraper that reaches 1 or 2 miles into the sky is an enormously difficult task, with associated costs running into the billions of dollars. The first major obstacle is rethinking structural design. It’s not as simple as stacking one half-mile-high building on top of another.

One key issue is that building a massive vertical tube, perhaps 500 to 700 feet in diameter and 1 or more miles high, would be a waste of space. Most of the interior floors would lack windows, leaving vast areas dark and undesirable for residential or commercial use. No one wants to live or work in a windowless cube, especially not in a skyscraper that promises breathtaking views.

Solution: The solution is to build slender skyscrapers that taper as they rise. This design allows for more desirable spaces with windows and views on every floor. The Burj Khalifa in Dubai, currently the world’s tallest building, tackled this problem using a buttressed core design. This design features a central hexagonal concrete core supported by three triangular buttresses, similar to the fins on a rocket. The structure tapers as it ascends, ensuring that all interior spaces are close to the building’s exterior and have access to natural light.

However, even with tapering, the lower floors of a mile-high tower would still be too wide to be practical. These vast spaces, far from windows and sunlight, could only be used for parking, maintenance rooms, storage, or indoor attractions like zen gardens, theme parks, or malls.

Elevator Challenge: Another significant challenge is the elevator system. A 1-mile-high building with 530 floors could house up to 50,000 people at once, including office workers, residents, tourists, and more. Conventional elevators are too slow and cannot handle the weight of cables extending a mile high. Additionally, switching elevators every 100 floors would be a logistical nightmare.

Solution: The Finnish elevator company Kone developed UltraRope, an ultra-lightweight carbon fiber cable that doubles the distance an elevator can travel. However, German firm ThyssenKrupp has gone even further with its cable-free elevator design. In this system, elevator cabins are outfitted with permanent magnets that interact with electric coils in the hoistway, allowing the cabins to move vertically and horizontally in a loop, similar to a Maglev train. This design reduces the number of required elevators and frees up space on each floor.

The Battle Against the Wind

Wind is a formidable opponent when it comes to constructing ultra-high skyscrapers. Wind pressure can cause significant sway, which can lead to structural failure or, at the very least, make the upper floors uncomfortable for occupants. The challenge is to design a building that not only resists wind pressure but also minimizes sway to ensure safety and comfort.

Solution: Engineers typically use two methods to address this issue: dampening or confusing the wind. The first method involves installing a tuned mass damper—a large counterweight that moves to balance the building’s sway. For example, Taipei 101 in Taiwan has a 730-ton spherical pendulum that reduces the impact of typhoons and storms.

The second method involves designing the building to change its shape as it rises, disrupting the wind’s ability to build up dangerous pressure. This can be achieved by shrinking each successive floor plate or by incorporating aerodynamic features like channels, fins, and curves that redirect the wind. The key is to accurately calculate these elements to prevent creating a vortex that could worsen the building’s sway.

Building Materials for Super-High Skyscrapers

Today’s best material for constructing ultra-high skyscrapers is high-performance concrete reinforced with microfibers. This material is stronger than structural steel and can withstand the immense pressures involved in such constructions. However, the choice of materials also depends on the building’s location.

Foundation Systems: In regions like the Middle East, where rock beds are rare, engineers have developed systems that defy conventional wisdom. A 1 or 2-mile tower in the desert might use a cast-in-place reinforced concrete bearing wall system with a buttressed core. This system involves a central hexagonal concrete core supported by three triangular buttresses, with walls interconnected by beams that resist lateral loads from wind and seismic activity.

These buildings would be anchored by a foundation system combining piled rafts—thick, straight-shaft, augered reinforced concrete piles extending up to 400 feet deep. The piles would transfer the building’s weight through friction with the ground, with a reinforced concrete raft slab distributing the load evenly.

How High Can We Go?

While the current record holder, the Burj Khalifa, stands at 828 meters (2,717 feet), there are already plans for taller structures. The Jeddah Tower in Saudi Arabia, once completed, will reach 1 kilometer (3,281 feet). However, the dream of a mile-high skyscraper is still on the horizon, with engineers and architects continuously pushing the boundaries of what’s possible.

Other Interesting Facts

• Vertical Cities: The concept of vertical cities is gaining traction as a solution to urban sprawl and overpopulation. These cities would house tens of thousands of people in a single, self-sustaining skyscraper, complete with residential, commercial, and recreational facilities.
• Sky Lobbies: To address the elevator challenge in super-tall buildings, many skyscrapers incorporate sky lobbies—intermediate floors where passengers can switch to express elevators that only stop at certain levels. This system reduces travel time and increases efficiency.
• Wind Tunnels: Before construction begins, models of super-tall skyscrapers are tested in wind tunnels to simulate the impact of wind at various heights. These tests help engineers refine the building’s design to minimize sway and ensure structural stability.

Conclusion

Building mile-high skyscrapers is not only possible but increasingly likely as engineering and materials science continue to advance. These towering structures could redefine city skylines and offer solutions to some of the most pressing urban challenges. However, the question remains: Is it worth the billions of dollars required to build such colossal towers? Could these structures help solve problems like urban sprawl and congestion?

We’d love to hear your thoughts. Let us know in the comments, and don’t forget to like and subscribe for more insights into the world of extreme engineering.