Cities Sprawl Higher

Residents of the Western Hemisphere may not know it, but we are living in the age of the "megatall" skyscraper.

First came "supertall" towers, those topping 300 meters (984 feet). But as of a little more than a decade ago, construction began on the first megatall building, defined as one that stands 600 meters (1,969 feet) or more. The first megatall structure was Burj Khalifa in downtown Dubai. Since its completion in 2009, the Burj Khalifa has been the tallest artificial structure in the world.

But it will not hold on to that designation much longer.

Construction is already underway on the Jeddah Tower in Saudi Arabia. Also called the Kingdom Tower, the structure is planned to reach 3,281 feet upon completion, expected in 2020. The tower will house a hotel, offices and residential apartments, as well as a 157th-floor observation deck.

The Kingdom Tower will shoot past the Burj Khalifa and other existing megatall structures, including the 2,073-foot Shanghai Tower, Saudi Arabia's existing 1,971-foot Abraj Al-Bait and the 1,965-foot Ping An International Finance Centre in Shenzhen, China, mostly complete and slated to be finished next year. New York's supertall One World Trade Center, reaching a patriotic 1,776 feet, is the only building in the Western Hemisphere to make the current top 10 list, and it may soon find itself pushed out completely.

Even the Jeddah Tower may not have long to enjoy its place at the top. British-Iraqi architecture firm AMBS announced plans in late November for "The Bride of the Gulf," a proposed tower in Basra, Iraq, to reach 230 stories, or about 3,780 feet. While there is no definite site yet dedicated to the project, it is another indication of the appetite to push architecture ever upward.

Some tall and supertall skyscrapers are purely residential, especially in the United States. Advances in engineering and technology, as well as increased population pressure in urban areas, make living dozens of stories up a more appealing prospect than it once was. But among the megatall structures that are cropping up around the world, dedicating an entire tower to purely residential use is rare.

Instead, many of these megatall buildings include business and residential portions, along with hotels, restaurants and a variety of in-house amenities. In effect, they are the most prominent evidence that cities today are as apt to sprawl upward as outward. In size and in function, they are effectively several skyscrapers in one.

Mixed-use towers offer some economies of scale. The restaurant where workers grab lunch on Tuesday will happily serve brunch to residents and hotel guests on Sunday. The shops, gardens and health services offered to residents will, in effect, make the tower a relatively self-contained community. The climate control system will be able to draw cooler, cleaner air from the stories far above street level, saving on cooling and filtration costs. And infrastructure such as a water mains and electricity will obviously be consolidated.

For some residents, too, there might be individual savings. Office workers may rent apartments in the tower where they work, reducing their commute to an elevator ride. Visitors seeing friends or family will be able to stay in hotel rooms just a few floors away.

Much as ocean liners have sometimes been described as "floating cities," multiuse towers like the one underway in Jeddah may represent "climbing cities." As such, they will need redundancies and safeguards for power, sanitation and emergency services. Some of these will simply be a matter of planning ahead; others may require innovative solutions.

For example, how do you fight a fire on the 70th floor of a building? In Dubai, the proposal is to outfit firefighters with "jetpacks," powered by helicopter blades rather than streams of gas, but still intended to allow individual first responders to rescue stranded civilians. While New Yorkers should not expect to see the FDNY flying around One World Trade Center's upper levels any time soon, futuristic skyscrapers already demand unusual solutions to unique problems.

Modern design also allows these towers to be built with increasing efficiency of materials. Engineering techniques such as a weight-bearing "exoskeleton" on the outside of tall buildings and the availability of stronger steel and concrete mean that builders can execute architects' designs while keeping costs manageable and buildings safe for the people who will live, work and relax in them once they are complete.

In North America and Europe, land use and zoning rules often prevent mixed-use buildings like those gaining prominence elsewhere. Such structures are either banned outright or require zoning variances blocked by people who would may not be directly affected at all, but dislike the idea of such a project in their backyard on principle.

And by international standards, the United States is fairly adaptable where building permissions are concerned. It is harder to imagine supertall, mixed-use skyscrapers gaining a foothold in Berlin or Milan, let alone Paris, where the announcement of a 590-foot tall combination hotel and office building created hand-wringing and outcry just months ago.

In some ways, supertowers may offer what urban living advocates have championed for years. They reduce the need for cars and other transportation, allow communities to deploy resources more efficiently and offer improved amenities through economies of scale.

On the other hand, these towers stand in opposition to calls for "human scale" development. Some urban planners have argued that focusing too much on efficiency can lead to isolating and even dangerous results for individuals. To remain viable, mixed-use towers will probably need common spaces such as gardens, courtyards or gallerias, as well as the proposed restaurants and shops that will make life social, not simply efficient, for the people who live and work in such places.

While megatall skyscrapers pose a variety of challenges, more nations are tackling these problems all the time. Towers like the one rising in Jeddah are one vision of the future, and one that is arriving first in the global East.

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