British Airways i360 is the world's tallest moving observation tower. It carries 200 passengers at a time in a circular glass viewing pod, which rises slowly from beach level to a height of 138m. The tower is 162m high and only 3.9m in diameter (awarded the Guinness Record for the "world's most slender tower"). The tower was delivered by barge directly to the beach and erected by a novel "top down" method without the use of cranes. It features purpose-designed perforated cladding to minimise vortex shedding, and sloshing liquid dampers to limit wind-induced dynamic movements.
The steel tower is clad in perforated aluminium Expamet sheet, which cleverly reduces the wind forces on the tower, allowing it to be so slender. To help still further in resisting any dynamic movements when the wind is blowing, the tower has another trick up its sleeve. It hides 78 containers on the inside of the tower, each filled with Australian water, positioned perfectly to help resist movements which the tower might otherwise want to make under wind gusting.
Another innovation lies in the manner in which the tower was constructed. It comprises 17 ‘cans’, each weighing between 50 and 100 tonnes, which were jacked up one by one in a top-down method of construction by using a jacking frame. This avoided the use of unfeasibly large cranes, and ensured that all construction occurred safely at ground level. And you’ll be happy to know that over 60% of the energy used to lift the pod each time is recovered on its descent. A remarkable feat of engineering.