Japan builds Tokyo Sky Tree, world's tallest tower

Standing 2,080 feet tall, the Tokyo Sky Tree is a new digital broadcast tower built on reclaimed land in the Japanese capital. Engineers are confident it won't topple in an earthquake.

Tim Hornyak/CNET

TOKYO--Nearly a year after the magnitude-9.0 quake that pummeled Japan, construction of the world's tallest tower, the Tokyo Sky Tree, is now complete.

Builder Obayashi, which recently announced plans for a space elevator to start services by 2050 , declared the Sky Tree complete ahead of a ceremony Friday. While the world's tallest man-made structure remains the Burj Khalifa in Dubai at 829 meters (2,720 feet), the Sky Tree tops the list of the tallest free-standing towers at 634 meters (2,080 feet).

It's 34 meters taller than the Canton Tower in Guangzhou, China, and nearly twice the height of its predecessor, Tokyo Tower (333 meters). Operated by Tobu Railways and a consortium of media companies, the Sky Tree will serve as a digital terrestrial broadcasting center for Tokyo and the surrounding Kanto region.

The achievement came amid snowy weather in Tokyo. Falling ice from the structure has been a problem for nearby companies and residences in Sumida Ward, a heretofore quiet district on the eastern bank of the Sumida River.

The land is known to be relatively unstable and much of the area was reclaimed from Tokyo Bay long ago. But engineers say the Sky Tree will be able to withstand even the strongest of earthquakes. They point to a traditional building technique that was incorporated in the structure.

The Sky Tree makes use of a shinbashira, a central column that features in the architecture of Japanese pagodas. The column acts as a stationary pendulum to counterbalance seismic waves, greatly reducing the sway in the surounding structure.

Indeed, there are virtually no records of pagodas being toppled in quakes in Japanese history. The tallest wooden tower in the country, the 55-meter (180-foot) pagoda of Toji temple in Kyoto, has been standing firm since 1644.

The Sky Tree's shinbashira is a hollow concrete tube housing elevators and stairs. It's structurally separate from the exterior truss but is joined by oil dampers, which help reduce quake shaking.

"The anti-quake measures in this structure can reduce quake vibrations by 50 percent," Hirotake Takanishi, PR manager for Tobu Tower Sky Tree, told me. "We've run simulations showing the Sky Tree will withstand an 8.0-magnitude earthquake, and can withstand even stronger ones, but we can't say definitely what its upper limit is."

The building suffered virtually no damage in the March 2011 quake, though supply interruptions delayed its completion.

Opening in May, the Sky Tree will have several cutting-edge attractions, including a special observation deck at 450 meters (1,476 feet) that will have an "air corridor" that snakes around the exterior for vertiginous thrills.

Stunning panoramic views
When I visited the Sky Tree on a press preview late last year, I rode the high-speed elevator to the first observation deck at 350 meters (1,148 feet) above ground. I couldn't feel the car's acceleration because it's engineered for a very smooth ride, but I was whisked up in less than a minute.

The view that greeted me was a stunning panorama of Tokyo spreading out in all directions over the Kanto plain. The world's largest metropolitan area, home to some 30 million people, seemed infinite.

Though Tokyo suffers from haze, on clear days in winter Mt. Fuji, Japan's iconic volcano, is visible to the southwest. The 360-degree deck also has a reproduction of a folding screen painting from Japan's feudal period that bears a remarkable resemblance to the panorama. It's a bird's eye view of Edo, the shogun's capital that was the precursor to Tokyo.

Indeed, the past is never far away at the Sky Tree. In Japanese, its height of 634 (meters) can be pronounced "mu-sa-shi," which refers to Musashi, the ancient province that was home to Edo.

Check out more pics in our gallery above, as well as the time-lapse video below of the Tokyo Sky Tree being built.


 

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