This article was first published in the November 2015 issue of WIRED magazine. Be the first to read WIRED's articles in print before they're posted online, and get your hands on loads of additional content by subscribing online.
Skyscraper heights have long been constrained by 19th-century lift technology. Thyssenkrupp wants to change this with its maglev Multi. Will it get off the ground?
Deep inside the carcass of a monstrous concrete tower under construction in Southern Germany, Andreas Schierenbeck picks his way carefully across scaffolding boards layered with dust and puddled with water.
Wearing a hard hat, he stoops to avoid dangling cables and timber supports, then stops to point into a narrow abyss at the edge of the platform. "Eighty metres," he warns. "Straight down."
Directly overhead, a construction crew works with deafening power tools, dismantling the forms they've used to mould the most recent layer of concrete, part of a round-the-clock building process that has caused the tower to rise at more then three metres every 24 hours. When it's finished, Schierenbeck's tower, which is in Rottweil, 100km south-east of Stuttgart, will reach 244m -- making it one of the tallest buildings in Germany -- and will have the highest observation deck in Europe. It will be sheathed in an elegant corkscrew of pale fabric -- almost indestructible, translucent, held under tension like a sail -- designed to change colour as the Sun moves across the sky. The architects, Helmut Jahn and Werner Sobek, call the project The Tower of Light.
And yet, even at a total cost of €60 million (£43m), the building will never be inhabited: Schierenbeck, CEO of multinational conglomerate Thyssen-Krupp's elevator division, intends the Tower of Light for use as a lift test tower, designed to experiment on prototype lift cabs, hoist systems and ropes. The core of the building will contain almost nothing but empty space: nine parallel lift shafts, in which every component of the company's new lifts can be tested -- to destruction, if necessary. Pointing into another concrete well yawning below, Schierenbeck explains that the bottom will be reinforced to take the impact of an entire lift cab free-falling at terminal velocity, up to a maximum of 40 tonnes travelling at 160kph.
Yet that isn't the reason Schierenbeck, an electrical engineer with a background in software who arrived in his new position two years ago, has ordered the construction of the Tower of Light. ThyssenKrupp already has a more modest test centre at its elevator plant, 100 kilometres away in Neuhausen. But that one -- like the test towers of each of the company's major competitors around the world -- is only designed to accommodate conventional lifts. Schierenbeck has something revolutionary in mind -- a lift he calls the Multi, a ropeless version that can move not only vertically, but from side to side. So three of the shafts rising within the tower, specifically designed for the Multi, have no walls separating them from one another. It's within these that he hopes to test a lift that will change the way that the buildings -- and thus the cities -- of the future will be designed. But before any of that can happen -- before his tower can fulfil its purpose; before his startling innovation can redraw the topography of the world's major cities -- the engineers at ThyssenKrupp will have to build a working prototype of the Multi. Schierenbeck admits they haven't managed that yet. But he remains optimistic. "Otherwise I wasted €60m -- plus the construction of a test tower," he says. "And I'm not prepared to tell my bosses that story."
Mechanical lifts have existed for centuries, but the version we know only appeared with the arrival of the safety brake, and the shift from steam power to electricity, in 1895. Since then, the concern of manufacturers has been improving lifts' speed, while keeping the basic, rope-based design in place. This is what ThyssenKrupp wants to change.
EARLY TRY: Inventor Elisha Otis gives the first demonstration of a lift fitted with a safety brake, in New York in 1854.
COMPETITION: Other models appear, like the steam-driven "vertical railway" and The Paternoster, a chain of cabins on a loop. The electrical traction lift triumphs.
Lifts have existed in some form almost since the beginning of civilisation. Archimedes recorded his ideas for hoisting devices and, in the 17th century, the German mathematician Erhard Weigel had a pulley system installed in his seven-storey home. In 1804, a six-storey freight and passenger lift was built in a Derbyshire cotton mill, and this was followed by numerous freight lifts installed in factories and mines throughout Europe. All worked on the same simple principle: a car or platform hoisted up and down using ropes, chains and counterweights.
At the Exhibition of the Industry of All Nations in New York's Crystal Palace in 1854, Elisha Otis gave a public demonstration of a lift safety brake. He instructed an assistant to sever the hoist rope with an axe: the surprise being that the lift did not fall to the ground, but was arrested by a safety catch. The public paid less attention to this than to the "vertical railway" that followed soon after, the invention of an all-but-forgotten mechanic, the confusingly named Otis Tufts. This was the first passenger lift with a completely enclosed cab, which travelled slowly but safely up a shaft on a steam-driven iron screw running through its centre. Only ever installed in two locations, in one hotel in New York and another in Philadelphia, Tufts' lifts proved longstanding tourist attractions. Others raised on hydraulic rams followed, but these could reach only a limited height, and were eventually supplanted by electrically operated traction lifts.
In 1931, the Empire State Building, with a core of 64 lift shafts serving 102 storeys of office space, became the world's tallest building. All of its lifts, controlled by an individual operator who travelled inside the car, were suspended from six or eight hoist cables wound around an electrically operated drum, or sheave. A counterweight, about 40 per cent heavier than the empty car, ran on its own rails to assist the lift's ascent, and emergency brakes tripped by a separate governor cable could slow the car to a gradual stop in the event of a runaway descent.
Simple and beautifully energy-efficient, the version of the traction lift installed in the Empire State was the state of the art in lift design -- and would remain so, virtually unchanged, for 60 years. This created a bottleneck in urban development, because it limited the number of people who could move through a building at any one time. As architects began conceiving taller and taller new buildings, they found themselves hobbled by the limitations of a means of transport that had apparently reached its ultimate iteration in the 19th century. "It's an interesting industry because it's really very old," Schierenbeck says. "It really developed at the same time as electricity was coming in vogue. If we're talking about industry 4.0, this is industry 1.0."
Today, the industry is dominated by five major manufacturers: Otis, which has grown from Elijah Otis's family firm to become the largest lift manufacturer in the world; Schindler; Kone; Mitsubishi; and ThyssenKrupp, a relative newcomer that entered the field in 1954. For decades, they have been engaged in a battle characterised by incremental improvements in technology and com
petition for bragging rights of the world's tallest buildings -- especially with the new supertall towers, including the Burj Khalifa in Dubai (Otis) and the Shanghai Tower (Mitsubishi). The battle has been confined to speed: "The thing to do for building designers is to build the world's tallest towers," says James Fortune, one of the leading independent lift consultants. "The thing for elevator designers is to build the fastest elevators." Schierenbeck intends to ignore this vertical grand prix -- and overtake his competitors by abandoning the course altogether.
Installing the correct number of lifts in a high-rise building is a delicate and arcane task. "It's all based on people," says Fortune, who has spent more than 40 years advising architects and developers on lifts for high-rise buildings, including Burj Khalifa and the Kingdom Tower in Jeddah which, when complete, will be the tallest skyscraper in the world. To keep tenants happy, there must be plenty of lifts available. But to keep landlords satisfied, there cannot be so many lifts installed that the shafts and machine rooms necessary to accommodate them gobble up too much of each floor's valuable footprint. In very tall buildings, this balance is complicated further by the tensile limitations of wire rope: a single elevator can climb no higher than 520 metres, above that and the rope it's suspended from becomes too heavy to bear its own weight. Beyond 1,000 metres, a length of wire rope will snap. But, in the early 70s, the designers of the World Trade Center in New York created a compromise solution to the enduring headaches of vertical transportation: the "sky lobby".
Providing transit points for passengers to move from one set of lift shafts to another, the sky lobbies divided the 110-storey towers into three vertical zones, each served by their own lifts; passengers travelling into the upper two zones of the building had to take an express lift to a sky lobby and transfer to a second, local, lift that would take them to their destination. The lifts in the World Trade Center were some of the largest ever built, designed to hold up to 50 people at a time, with doors opening at both front and back to speed up the flow of passengers. But each elevator shaft could still be occupied by only one car at a time, and this continued to cap the pace at which people could be moved up and down the building. Subsequent holders of the "world's tallest building" title -- the Sears Tower in Chicago in 1973, succeeded in 1998 by the Petronas Towers in Kuala Lumpur -- introduced double-decker lifts that could serve two floors simultaneously.
For decades, lift engineers had recognised how much more efficient it would be to have more than one car using the same lift shaft. First installed in Britain in the 1880s, The Paternoster -- a chain of open-fronted cabins moving on a continuous loop -- offered one solution. But because the design placed the weight of all the cars and their passengers on a single overhead axle, it was useful only in low-rise buildings. A similar concept called for a loop of lifts travelling in a spiral around the outside of a building, and in the early part of the 20th century several patents were filed to put two conventional roped lifts in the same shaft. Every one of those patents expired -- foundering on the limitations of existing technology to prevent collisions. All the while, lift engineers continued to imagine an even loftier target: a version entirely free of hoists, cables and pulleys. By the 90s, technicians at more than one of the world's lift manufacturers believed that the best chance of creating a truly ropeless lift lay in another technology that had been around in one form or another for more than a century: using linear induction motors to create magnetic levitation.
Now a veteran of lift engineering who has spent his entire 24-year career with ThyssenKrupp, Markus Jetter was just starting work with the company when he spotted a technician struggling with the problems of magnetic levitation. Jetter, a lanky 61-year-old with wire-framed glasses and receding black hair turning to grey, is a lift obsessive. He admits to sneaking away from his wife and three children during family holidays to use apps on his iPhone to measure the speed and comfort of the competition's more prominent high-rise lift installations. He is so coy about their products that he cannot bring himself to mention the names Otis or Schindler in conversation. Jetter is also rigorous about industrial secrecy: he receives a weekly patent alert that keeps him informed of what the engineers at the other companies might be up to. WIRED asks what he was able to tell his family about what he was working on during the ten years he spent on the Multi programme. "The revolution," he laughs.
On his introductory tour of the development department in 1991 at the headquarters of the ThyssenKrupp lift division in Neuhausen near Stuttgart, Jetter noticed an engineer sitting at an empty desk with a laptop: he was attempting to apply the principles of maglev railway technology to vertical transport. The company was already a leader in the maglev field, having been at work on a high-speed maglev train -- the Transrapid -- since the early 70s, and had already built several passenger-carrying prototypes.
Jetter recognised that propelling a train horizontally down a track, hovering on a frictionless electromagnetic cushion -- and up the occasional mild incline -- was a very different proposition to levitating a fully loaded steel lift car up a shaft. But eventually, in 2000, the ThyssenKrupp engineers built a successful small-scale prototype at the University of Aachen in the Netherlands that could lift its own weight using linear induction. "From that point," Jetter says, "many in our company considered linear drive to be possible: 'We can do it! We can see it! We have this prototype!'"
MODERN LIFE: In the US, lifts become widespread by the end of the 19th century. With steel frames, the safety lift brings about skyscrapers and the development of the modern city.
EMPIRE STATE: The then world's tallest building, the Empire State Building is completed in 1931. Its 102 floors are served by 64 lifts.
Yet there remained many profound problems that had to be solved before the experimental system could be scaled up to carry passengers. Traction lifts are built from steel for reasons of strength and safety and, because it helps create a stable and comfortable ride, are often better the heavier they become. But a levitating lift car needs to be constructed from something both very lightweight and extremely strong; at the time no such material had been tried. Even more importantly, although a linear drive lift promises to be entirely ropeless, the engineers had no means of ensuring two or more of them could safely share the same shaft without the risk of collision. "It wasn't possible," Jetter says. "There was a missing link in the technology."
While ThyssenKrupp's maglev lift languished on a drawing board in Germany, across the Atlantic Otis had already filed patents on a new concept they called Odyssey. This was a reimagining of the original sky-lobby idea, also using linear-induction motors. ("You will find everybody in the elevator business who wants to omit the ropes, they say the only way is a linear drive," Jetter says. "That is common sense.")
In the Odyssey system passengers would sit in enclosed "transit pods" that could travel across the lobby on a horizontal track before being carried to their final destination by one or more conventional lifts. Passengers would climb into the transit pod on the ground floor, which would then move under its own power into a lift; on arrival in the sky lobby, the pod would then travel into a second lift to rise horizontally towards its destination where the passengers would disembark. Otis built a prototype but it never made its way into production and was shelved after the 1997 Asian financial crisis.
In the meantime, one of the missing links that had held back ThyssenKrupp's ropeless solution had been filled in by its competitors. In 1996, Schindler pioneered the use of microprocessor-controlled smart lifts, in which "destination dispatch" software cuts down the number of stops each lift makes.
Destination dispatch lift cars contain no buttons at all; instead, each passenger selects the floor they're heading for from a keypad near an elevator bank. Then an algorithm groups together passengers sharing similar destinations and chooses a lift for them to share, thus reducing journey times.
The foundation of destination dispatch control -- soon adopted by all major manufacturers -- is that each smart lift must know its position in its shaft relative to all the others in operation. This meant that two lifts could potentially occupy the same shaft.
In 2000, a team of four ThyssenKrupp engineers went to work on the final stage necessary to make the idea a commercial reality: an electronic system to manage the distance between cars and ensure they never came too close to one another. Not only was this the key to a truly viable two-cabin system, but -- because everything else about the idea had been imagined at least 70 years earlier -- it was also the one part of the technology the company could patent. In 2003, having devised a proprietary system of proximity control with an algorithm, bar codes and magnetic tapes, the company marketed the Twin lift system.
Jetter and his team turned their attention to the future. "What," he asked, "is the next step?" They returned to thinking about linear drive motors and lightweight carbon-fibre ropes that could extend the height of traditional lifts.
Progress was slow. The engineers were happy to work on new ideas, but according to Schierenbeck few of them believed that anything truly revolutionary was possible. "We are a very traditional industry," he explains. "Very, very conservative."
SKY LOBBY: As a lift's ropes only have a range of 520 metres, the Empire State holds the height record for four decades. In 1969, the introduction of the "sky lobby" makes taller buildings possible.
STANDSTILL: Since then, the sector hasn't seen much technological innovation. The industry is dominated by five giants -- Otis, Kone, Schindler, Mitsubishi and ThyssenKrupp -- competing over the contracts for today's tallest buildings.
Soon after he arrived at ThyssenKrupp Elevator from Siemens at the end of 2012, Andreas Schierenbeck chaired his first annual innovation meeting at the company's headquarters. ThyssenKrupp Elevator has grown largely through acquisitions of smaller lift companies. It now maintains four semi-autonomous idea labs around the globe, each housing 20 to 30 technicians who often collaborate with teams of university researchers.
At the meeting, he took reports from every one of the company's innovation centres; each one outlined their projects in development and associated budget requests. "We approved every single project, and there was still money left," he says. This meant only one thing: "We didn't have enough ideas." Schierenbeck was shocked. He needed to commit his company to a technological leap, and he wanted to do it quickly. His engineers knew from examining the patent landscape that in Finland, Kone, like them, was already at work on developing a lightweight rope that might take lifts higher than ever. But as far as they could tell, nobody else was working on multiple cabs in a single shaft or linear motors. Schierenbeck told the innovation teams to concentrate on building a prototype ropeless lift.
At the beginning of 2013, in ThyssenKrupp's German research centre in Pliezhausen, Markus Jetter's team set to work combining the work they had done on the Twin -- the proximity-management software and other safety systems that made it safe to run multiple cars in a shaft -- with linear motor technology. The engineers grew ten or 20 decision-tree branches for every component of the system -- more than 100 in all. They produced a car within a viable weight budget and devised a passive electromagnetic braking system to arrest the cabin safely in the event of a power failure. The greatest challenge remained how to transfer the car from one shaft to another. They considered 20 solutions for this "exchanger", including a cage designed to capture the lift car at the end of its vertical run and then carry it horizontally, driven by a second propulsion system.
HOW THE MULTI NAVIGATES A BUILDING
ThyssenKrupp's new project aims at getting rid of cables and counterweights by using "maglev" railway technology to build a ropeless lift. In the same way that trains slide along a track, this new lift would shoot up the building riding an electromagnetic field. But maglev would allow for more than just vertical travel: when a lift reaches a transfer station, it could move horizontally to another shaft. Lift shafts would be transformed into complex, railway-like networks.
To make the final decision, the team built a pair of one-third-scale mock-ups of the two best exchanger concepts, and in September 2014, the company's research and development council -- some 30 managers and engineers -- was summoned to Stuttgart from around the world to select a winner. There was little debate: one of Jetter's concepts had proved so complex and difficult that it had been hard even to complete the mock-up; it didn't receive a single vote.
But the other exchanger seemed superficially simple: the car was propelled by the linear drive along a track until it reached a transfer station. At that point, a section of the track itself turns through 90 degrees, to allow for horizontal movement into a parallel shaft. The cab then travels horizontally under its own power until it reaches the second shaft, where the receiving track rotates once more to the perpendicular, and the cab continues on its vertical journey. This would make it possible for lift cabins to be treated like train carriages: they could move anywhere and in any direction within the system, and more cars could be added to it for use at peak times, or easily removed for maintenance.
With this piece of the technology finally in place, Schierenbeck gave the go-ahead to build the gigantic €60m test tower. In November 2014, ThyssenKrupp finally made an announcement: "The era of the rope-dependent elevator is over," read the press release, describing a technology that would enable architects to design buildings with previously impossible floorplans, and super-high-rises now navigable by Willy Wonka-style elevators that could travel up, down and sideways -- even diagonally. It was, according to ThyssenKrupp, the industry's ultimate goal.
With the Tower of Light due for completion by the end of this year, Schierenbeck hopes to have a full-sized prototype of the Multi ready for test there in 2016.
Elevator consultant James Fortune is not so sure. "They're on the right track," he says. "But they've got a long way to go." Fortune believes there remain too many unknowns with such a concept -- it lacks, for instance, the power efficiencies of a traditional lift; it has yet to be shown how many people a maglev motor can carry vertically; and horizontal movement is so disorientating in an enclosed space that passengers might simply fall over when the car stops. "It's not a perfected system," Fortune says. "I'd say they're ten years away -- minimum."
Meanwhile, Kone is planning to install its strong, lightweight carbon-fibre Ultrarope in lifts serving the Kingdom Tower, helping them become the highest single-drop lifts in the world. Mitsubishi plans to take the prize for Earth's fastest lift with those it is installing in the Shanghai Tower, which it claims will reach 64kph. But forAndreas Schierenbeck these feats are just a sideshow. "It's not solving all the limitations of that technology," he says. "You still have one cabin in the shaft."
Markus Jetter seems confident his work will pay off. When asked to describe the most crazy and unworkable solutions his team had thrown out during the development of the Multi, he says that the engineers were forbidden to call any idea unworkable. "It's difficult to deal with colleagues who say, 'This will never work, or this is crazy,'" he says. "We call it 'idea crushing'. These are all statements discouraging people."
Just look back in history, he says. "These crazy ideas became thrilling technology."
Adam Higginbotham wrote about Dean Kamen in 08.13
Visualisation: Oliver Burston. Photography: Alamy; Getty; Corbis; Ralf Graner
This article was originally published by WIRED UK
