Innovative jacking mechanism used to build new Brighton landmark.
Eleven years after it was first conceived, the “world’s tallest moving observation tower” has opened to the public on Brighton’s seafront.
The £46m British Airways i360 tower, designed by Marks Barfield, designer of the London Eye, comprises a giant glass-and-steel doughnut that moves up and down a 162m high pole, offering views of up to 42 kilometres in all directions.
The tower consists of 17 steel cans that are stacked and bolted together forming the world’s most slender tower, with a diameter of just 3.9m at its widest point.
“Built at the landward end of Brighton’s historic West Pier, British Airways i360 is a modern day ‘vertical pier’ that gives a new perspective on the city,” said Marks Barfield co-director David Marks. “Just as the West Pier invited Victorian society to walk on water, so British Airways i360 invites visitors to walk on air.”
The i360’s 18-metre-wide pod is 10 times bigger than the capsules of the London Eye and will hold up to 200 people at a time. It will rise to a height of 138m.
The attraction also includes a visitor centre with a 400-seat restaurant, a gift shop, a children’s play area, an exhibition gallery, and facilities for conferences and other events.
The studio first drew up plans for the i360 in 2005, but the project stalled in 2008 as a result of the global financial crisis. It was revived in 2014 by the local council, majority-funded by a loan from the UK’s debt management office.
The tower, which offers views of up to 26 miles of Sussex coastline, has divided local opinion. Valerie Paynter, of the Save Hove campaign, said it is “like something springing horribly out of the earth in a horror movie”. But Glynn Jones, chairman of the West Pier Trust, believes the “vertical pier in the sky” shows “the city is, once again, embracing and celebrating world-class, stunning architecture”.
Those going on board can see from Bexhill in East Sussex to Chichester in West Sussex with the South Downs to the north.
How the tower was built
The tower consists of 17 steel cans that are stacked and bolted together. The steel cans are all exactly 3.9 metres in diameter. The can wall varies in thickness from 85mm for the heaviest cans at the base, to 20mm at the top for the lightest ones.
The cans vary in length from about 4.5m to 12m with the shorter, heavier, ones at the base and the longer, lighter, ones higher up. The cans vary in weight between the heaviest at 85 tonnes and the lightest at 45 tonnes. The total weight of all 17 cans is approximately 900 tonnes.
The cans were made in Holland by “rolling” flat steel plates into a circular shape and then welding the seam where the two edges of the plate touch, by main contractor Hollandia.
i360 in numbers
- Trips last 20 min and cost £13.50 for adults and £6.75 for children
- The tower consists of 17 steel “cans” or tubes made in Rotterdam
- It contains 1,336 bolts weighing 30 tonnes
- The viewing pod is 59ft (18m) wide – 10 times bigger than a London eye capsule
Each can has a lip called a flange welded to its top and bottom to allow it to be bolted to neighbouring cans, or to the base. The flanges were forged from a red hot single ingot of steel, machined to the size required and welded to the cans.
After the flanges were welded to the cans they were machined for a final time, then “match-drilled” to precise tolerances so that they could be bolted accurately together on site. More than 18,000 man hours of welding were required to manufacture the tower cans.
On the outside, the cans were fitted with cleats for the cladding, electrical bus-bars, stiffeners around door openings, and pod stops. Internally, the cans were fitted with counterweight guiderails, stiffeners, access ladders, and access platforms.
After fabrication and fitting out, each can was hot metal sprayed with a mixture of zinc and aluminium, and then painted to protect the steel against corrosion. The cans were shipped to Brighton from Rotterdam in June 2015, landing on the beach in front of the site.
Tower can
