An artist's rendering of the Nippon Moon, a giant observation wheel planned for Japan. Image courtesy of UN Studio.

+ "I can see everyone's house from here!" The Nippon Moon is on track to be the biggest observation wheel yet - but could they get higher still? (Image courtesy of UN Studio)

The ‘Nippon Moon’ is set to be the biggest observation wheel yet and I see no reason why they can’t go higher still. 

As well as the Nippon Moon (designed by UN Studio), Arup has worked on the London Eye, the Singapore Flyer, the Las Vegas High Roller, and the redesign of the Melbourne Star. What’s been exciting for me about these projects is that engineering has helped make each one bigger and better incorporating unique and different structural forms.

If you’re building a giant observation wheel, it needs to have something special about it to ensure it will succeed. For example, you’ve probably never heard of the Star of Nanchang. It’s a 160m-tall wheel in China similar in size to the Singapore Flyer but its design doesn’t stand out. Its traditional lattice structure puts it in the realms of a fairground attraction rather than a significant piece of iconic structural architecture.

Much like the original Ferris wheel, the majority of modern-day wheels use simple tension spoke and compression rim structures (similar to bicycle wheels). The original Ferris wheel used a square rim structure whilst the London Eye reduced this to an elegant three-chord triangular truss form. The Singapore Flyer reduced this further to a two-chord ‘ladder’ truss that gives the wheel a very thin, elegant appearance. By the time of the High Roller, Arup was able to design a wheel with a single chord – one tube going all the way around.

Structural engineering is only one element of the challenge in getting a wheel built. Like any tall structure, the cost of giant observation wheels increases exponentially with height due to factors such as increasing wind loads. Plus the challenge of gaining the confidence of the banks and financiers is large, since it’s extremely difficult to accurately predict how many people will pay to ride a wheel.

You’d be forgiven for being cynical about whether it’s worth building giant observation wheels. However, they have proven their worth and become much-loved features of cities. (Just try and imagine London without its eye, for example.) I think this success stems from the fact that there’s something awe-inspiring about seeing such an immense circular moving structure, contrasting with the rectilinear buildings that typically form a city skyline, particularly if you’re a tourist visiting a new city.

For this reason I believe in the future we’ll see different types of ride that provide even more unusual experiences. For example, a ‘centreless’ fixed or stationary wheel called the  Big O already exists in Tokyo where the capsules rotate around the structure. At Arup we looked at a similar design for Sydney where capsules climbed, twisted and revolved around a structure in the shape of a giant spinnaker sail.

This sort of technology is still in its infancy. For the moment, I think the heyday of giant observation wheels will continue and while it does we should enjoy the ride.