10 Strange Structural Engineering Marvels

Most engineers don't want their skyscrapers to lean. In fact, a building that begins to list after construction almost always indicates a failure of design. The Leaning Tower of Pisa, for example, was built on weak, unstable soil, which caused the foundation to sink on one side. As a result, the famous tower pitches almost four degrees off-center.

Then you get crazy engineers who decide to make their structures lean on purpose. That's the case with Capital Gate, a 35-story skyscraper situated on the island city of Abu Dhabi, United Arab Emirates. By design, the structure leans westward a full 18 degrees -- more than four times greater than Pisa's famous tower. To pull this off, engineers drilled 490 piles almost 100 feet (30 meters) into the ground and built a solid foundation consisting of a dense mesh of reinforced steel [source: Salmi]. Then they erected what's known as a pre-cambered core -- a steel-reinforced concrete spine with a case of scoliosis. Because the core curves, the whole building curves with it. Workers had to cut the diamond-shaped panels to slightly different dimensions because each one fit at a unique angle.

In 2010, Guinness World Records designated Capital Gate as the Farthest Man-made Leaning Building. Not to be confused with the Farthest Man-made Leaning Tower, which, unlike a building, doesn't have usable floor space.

To connect the Norwegian cities of Laerdal and Aurland highway engineers were forced to solve a small problem: the Hornsnipa and Jeronnosi mountains. Instead of going around the obstacles, they decided to go through them. The result was the Laerdal Tunnel, which runs through solid gneiss rock for 15 miles (24 kilometers), earning it the title of the world's longest completed road tunnel.

Excavating such a structure is only one of the challenges. Designers also have to ensure that motorists can make the long, underground trek without succumbing to "highway hypnosis." To address this problem, the Norwegian Public Roads Administration called in a team of psychologists to make sure the finished roadway was as stimulating as possible. The agency recommended including blue lights and gentle curves to keep drivers engaged. They also suggested that the final tunnel be divided into four sections to help reduce monotony.

Motorists entering the Laerdal Tunnel today might not notice these design enhancements, but they'll certainly appreciate them when they emerge safely into daylight after the 20-minute journey through the middle of a mountain.

When most people think of a factory, they envision a huge box of blah topped with pollution-belching smokestacks. In 2001, Volkswagen redefined the concept of car manufacturing when it opened Die Gläserne Manufaktur -- "the factory made of glass" -- to produce the Phaeton luxury sedan. The building sits squarely in the heart of Dresden, Germany, in the northwest corner of the Great Garden, defying city planners who said manufacturing couldn't exist side by side with urban culture and living.

Then again, Die Gläserne Manufaktur isn't your normal industrial megastructure. You won't find any smokestacks, earthshaking noises or toxic byproducts here. The factory's walls contain 290,000 square feet (26,942 square meters) of glass, which means the public can see everything that takes place inside [source: Markus]. No doubt they probably drool over the Canadian maple floors or wonder why the front lobby looks like an opera house. But there's no question of what's happening inside when they catch a glimpse of the various Phaeton parts, rolling along conveyor belts and awaiting assembly by the factory's robots and 227 line workers [source: Markus].

It just could be the factory of the future -- or nothing more than a conspicuous display of corporate transparency.

If you tried to read the copy of "To Kill a Mockingbird" found on the Community Bookshelf outside Kansas City's Central Library, you'd be both disappointed and thrilled. First, the spine of the book measures 25 feet by 9 feet (7.6 meters by 2.7 meters). Second, the oversized spine doesn't bind a real book. It forms, along with 21 other literary favorites, a false front for the library's parking garage. Instead of hiding the garage behind the main building or settling for the standard block of concrete, the building's designers decided to keep the garage, which opened in 2004, front and center and make it part of the library-going experience.

The project team also involved the community. Kansas City residents suggested which titles to include on the bookshelf, and the library's board of trustees narrowed the list down to 22 works of fiction, nonfiction and poetry, including two volumes dedicated to Kansas City stories. Along with Harper Lee's masterpiece, you'll find "Catch-22" by Joseph Heller, "Fahrenheit 451" by Ray Bradbury, "Silent Spring" by Rachel Carson, "Invisible Man" by Ralph Ellison, "A Tale of Two Cities" by Charles Dickens and "Charlotte's Web" by E.B. White. They're all giants of literature, of course, now with a physical form equal to their stature.

Optical telescopes that offer game-changing views of stars, nebulae and exoplanets require just as much engineering ingenuity as dams, tunnels and bridges. For example, the primary mirror of the Subaru Telescope, which sits at the summit of Mauna Kea in Hawaii, has a diameter of 27 feet (8.2 meters) and weighs more than 25 tons. The structure supporting the optics and the enclosure surrounding the entire system rival any building in terms of complexity.

One of the biggest challenges with traditional telescopes is getting the mirror to the top of a mountain without breaking it. Then, once it's set up, astronomers must constantly tune the system to account for deformation caused by gravity, humidity and other environmental conditions. Liquid mirror telescopes, such as the University of British Columbia's Large Zenith Telescope (LZT), eliminate these problems. The LZT uses liquid mercury as its primary mirror, which can be poured at the site and can maintain a perfect parabolic shape as long as it rotates at a steady speed. It can reflect as much as 75 percent of incoming starlight -- and can do it at about one-fifth the cost of an optical telescope [source: Dorminey].

To date, the LZT holds the record as the largest quicksilver-spinning telescope in the world (it has a 6-meter/20-foot aperture), but India, Belgium and Canada are teaming up to build an even bigger model -- the International Liquid Mirror Telescope, which will do its stargazing from Devasthal Peak in northern India.

Over the last decade, the city of Dubai has experienced phenomenal growth, most of it concentrated on 37 miles (60 kilometers) of coastline bordering the Persian Gulf. Unfortunately, all of the high-rise apartments, skyscrapers and hotels stand shoulder to shoulder on the shore, leaving little room for new development. To solve that small problem, Nakheel Properties, a government-backed real estate developer, decided to extend the Dubai shoreline by building three man-made landmasses known as the Palm Islands.

How do you pull off such a feat? You pile up tons and tons of sand and rock until an artificial island emerges in the ocean. Workers dredged up more than 3 billion cubic feet of sand to build Palm Jumeirah, the first of the three islands [source: Dowdey]. But they didn't simply heap the stuff into a big mound. Instead, they created an archipelago in the shape of a palm with a trunk stretching 1.24 miles (2 kilometers), a crown made up of 16 fronds and a surrounding crescent. They used GPS data to make sure the structure retained its symmetry throughout construction.

In 2013, Palm Jumeirah remains the largest man-made island in the world -- at least until its companions rise from the sea. When it's completed, Palm Deira will be even bigger, occupying approximately 18 square miles (47 square kilometers) of land reclaimed from the Persian Gulf.

Its name suggests a completely boring structure. After all, what could be strange or intriguing about a rectangular stadium? But when you take a bird's-eye view of AAMI Park, as it's known in Australia, you can see why the design has been hailed as the "next generation of sports stadia" [source: The Institution of Structural Engineers]. The most distinctive feature is the roof, which draws inspiration from the geodesic domes of American engineer R. Buckminster Fuller. To build a geodesic system, you piece together interlocking polygons to form a sphere. The resulting structure is strong, yet uses far fewer materials than something similar built with traditional construction methods.

The roof of AAMI Park actually boasts several geodesic domes, packed together like a complicated soap-bubble surface. And yet the stadium still manages to use 50 percent less steel than a typical cantilever structure [source: Major Projects Victoria]. It also contains significant amounts of recycled building material, collects rainwater from the roof and minimizes power use with an advanced building-automation system. When it opened in May 2010, it collected a number of awards for architectural innovation, structural engineering excellence and eco-friendly construction techniques. But don't expect to hear the cheers of environmentalists. The stadium holds more than 30,000 spectators, who can get more than a little rowdy cheering for local soccer and rugby teams.

Speaking of leisure activities, the Ericsson Globe, a sports arena in Stockholm, holds a number of records. With a diameter of 361 feet (110 meters), an inner height of 279 feet (85 meters) and a volume of 21,188,800 cubic feet (600,000 cubic meters), it stands as the world's largest spherical structure. And, amazingly, it didn't take long to get that way. Workers broke ground on Sept. 10, 1986, and the building opened for business on Feb. 19, 1989. That means the entire construction process took just 2.5 years.

The size of the Ericsson Globe makes it perfect for more than hockey games and live entertainment. It also plays a role in the world's largest educational model. You heard right. The astronomy department at Stockholm University decided to depict the proper scale of our planetary system using structures spread across the Swedish countryside. The Globe serves as stand-in for the sun, which establishes the model's scale to be 1:20,000,000. All of the inner planets are located within Stockholm city limits, but the outer planets range far to the north. For example, Neptune resides in Söderhamn, which is 153 miles (246 kilometers) from the Globe, and the dwarf planet Pluto in Delsbo is 186 miles (300 kilometers) away. There's a host institution for each model, so tourists can travel to the planets without ever getting lost in space.

At first glance, the headquarters of China Central TV (CCTV) looks like something out of an M.C. Escher painting. And yet this is no fantastical vision of infinite loops and never-ending staircases. The building opened in 2012, after 10 years of design, development and near disaster. A fire in an adjacent CCTV building, in 2009, almost derailed the project, but you can't hold a good skyscraper down. Today, the oddball structure can be seen throughout Beijing and stands with the Bird's Nest and the Water Cube, two iconic venues of the 2008 Olympics, as a symbol of China's dynamic future as an international superpower.

The Dutch architectural firm OMA designed the building as, it said, "an alternative to the exhausted typology of the skyscraper" by throwing out the traditional straight-backed tower in favor of a three-dimensional structure. The loop is created by joining two leaning towers, top and bottom, with L-shaped connector bodies. Tower One has 54 floors and rises to 768 feet (234 meters); Tower Two has 44 floors and rises to 689 feet (210 meters). The overhanging cantilever jigs 246 feet (75 meters) to the west, then jags 220 feet (67 meters) to the south.

According to the OMA Web site, the architects drew inspiration from the television production process, which requires a loop of interconnecting activities. That may be a fanciful interpretation, but one thing about this structure is true -- it's no boring rerun.

Building big isn't the only way for engineers to make an impression. The Rolling Bridge, which allows pedestrians to walk over the Grand Union Canal in London, spans just 39 feet (11.8 meters). But its innovative design more than makes up for its diminutive stature. The bridge consists of eight timber-and-steel sections hinged together so that, fully extended, it lies flat. Then, under action of hydraulic pistons, the sections can lift and pivot to allow the entire structure to curl upon itself, much like a pill bug rolling into a ball. While boats pass through the unobstructed canal, the bridge sits on the bank like a piece of sculpture.

The Rolling Bridge is the brainchild of Thomas Heatherwick, who has designed other architectural oddities, such as the giant cauldron that burned during the opening ceremony of the 2012 Olympic Games in London and the B of the Bang starburst sculpture. In 2008, the city of Manchester asked Heatherwick to take down B of the Bang because it kept shedding spikes. So far, the Rolling Bridge has presented no such dangers. In fact, in 2005, it received a Structural Steel Design Award, with the judges noting that the bridge was a "joyful addition to the [Paddington Basin] development area that has all the appearance of a Leonardo sketch when in the 'rolled' position."