Jeddah's Kingdom Tower will be taller than any other structure ever built. At more than 1km high, this supertall will require feats of engineering that, until now, have been the stuff of science fiction. Like the world's tallest, longest and fastest lifts -- which are being developed in a mine shaft in Finland.
Kone, a Finnish elevator company, just announced that it won a contract to design and build 65 lifts for the Kingdom Tower -- a project that had been stalled until sputtering back to life earlier this year. The challenge will be a unique one: Lift technology is one of the major barriers standing in the way of supertall buildings.
First of all, supertall lifts are put under enormous and unusual stresses, like those introduced from wind shear. Traditional steel rope is very heavy -- and at supertall heights, the weight of the cord alone becomes massive. Then there's the heat issue: A lift plummeting in free fall is moving incredibly fast, and stopping it requires a brake system that can withstand temperatures of 300C. Those are just a few of the issues at play here -- not to mention efficiency and cost issues.
How does Kone expect to solve them? Using a technology called UltraRope that it introduced last year. Rather than steel, UltraRope is made out of a carbon fibre core and coated with a special high-friction chemical than can withstand incredible heat and force. Thanks to this coating, UltraRope lasts twice as long as steel cable.
And it's super-light, which means it takes less energy to hoist it up a kilometre-high building. Kone's head of technology told Construction Week that a 400m lift's steel cable would weigh 18,650kg. The same length of UltraRope cable weighs 1170kg.
Inside Kingdom Tower, Kone will build a series of lifts that double the current height limit, reaching up to 637m in a single shot. They will be heavy double deckers too, but they will cover 800m faster than any other lift in the world.
It's fascinating news, but it leaves one stone unturned: How do you design a lift before any buildings tall enough to test it even exist? Kone, thankfully, has quite a bit of experience here; it designed the lifts for 600m Makkah Clock Royal Tower, currently the third tallest building on Earth, as well as a handful of other supertalls.
To design all lifts for building so tall they don't exist yet, Kone does the opposite: It digs down. Way, way, down: 300m into a mine shaft in southern Finland that dates back to 1897. That abandoned mine was a perfect solution hiding in plain sight, and in 2008 Kone turned it into a lift testing facility.
It's the only testing facility of its kind on Earth, and though the maximum testing depth is only 300m -- not 1000m -- it's enough to test the technology Kingdom Tower will need.
"The goal was to develop the technology needed for super- and mega-high-rise buildings," Johannes de Jong, Kone's director of projects and technology, told Bloomberg last year. "This is the only test tower in the world where you can test speeds of 2000 feet (609m) per minute up to 3500 feet (1067m) per minute. Others have to rely on simulators, so it's an advantage."
It's incredible to imagine that the technology that will catapult average humans higher into the atmosphere than ever before is being developed hundreds of feet below ground. It will be another few years until Kingdom Tower starts to rise -- but it sounds as though, deep below an abandoned Finnish mine, the work is already beginning.