Markets & Sectors

Elevators and the city

27 Jun , 2019  

It is a simple idea: a carriage that moves up and down inside a building, allowing people to travel between floors without having to walk up and down stairs. It is also revolutionary. Over the course of 150 years it has played a key role in the transformation of the modern city: from low-lying layout of individually distinct commercial and civic buildings into dense, soaring stacks of offices and apartments. Skylines, once fixed, are now continually being revised upwards.

How was this astonishing change effected? What challenges did elevator engineering have to overcome to bring about the new architecture? How has the experience of city life been reshaped as a result? And what new ground has elevator technology yet to break – promising what new landscapes?

The evolution of elevators – a very brief history

What kicked off the age of the elevator was the safety breakthrough. Ancient Greeks and Renaissance Italians had both experimented with vertical carriage systems using hoists and pulleys, and novelty elevators started appearing in European royal palaces in the eighteenth century. But, despite counterweights and hydraulics ushering in the modern mechanical era, elevators could not go mainstream until they had won the confidence of ordinary people.

This was done in spectacular fashion at the New York Crystal Palace Exhibition in 1854 by inventor and industrialist Elisha Otis. With himself in position on the elevated platform before a crowd of spectators, Otis had the hoist rope severed by an axe: instantly, a wagon spring snapped open, pushed a pair of pawls into engagement with ratchet bars in the frame, and the platform did not fall.

The same safety apparatus was duly installed, as part of Otis’s first commercially successful elevator, in a five-storey Lower Manhattan emporium. Before the end of the century the world’s first skyscraper – the ten-story Home Insurance Building in Chicago – had been built and a new architectural aesthetic (the Chicago, or Commerical, style) established.

Lifts and elevators in the vertical city

Of course, elevators were only one aspect of the technology that fuelled the vertical surge of the city. Steel-frame architecture was equally important. Load-bearing structural skeletons for buildings were first made feasible towards the end of the nineteenth century by advances in the science of steel production. These gave the height; elevators the means of scaling it.

The first skyscrapers were not just enabled by elevator technology; they also challenged its early limitations. Hydraulic systems, for example, in which elevators are driven upwards by pressurised pistons, require substantial foundations, almost equal in depth to the system’s potential reach. For this reason alone they were quickly seen as unsuitable for very tall buildings.

lift-elevator-technology

Traction elevators – or roped – were the way forward and indeed have been used in every milestone of tall building construction through the twentieth and twenty-first centuries. Their simplicity of design and low energy requirements make them virtually infinitely extendable.

Once an elevator’s physical mechanism is strong and durable enough to service a great number of floors, it needs to be able to move people between them satisfactorily. Speed and efficiency of service must deliver on the structural promise.

How electric drives changed lift technology?

The transition from steam to electric power increased elevator velocity by many multiples: up to, in fact, the speed at which it is comfortable for a person to travel vertically (about 10 m/s). Just as valued by those who use it is an elevator that does not involve excessive waiting for the carriage’s arrival, nor tedious stopping at other people’s floors (both of which risks increase with the number of floors covered).

Since the 1950s (and the demise of the elevator attendant) elevator behaviour has been algorithmic. A widely used basic protocol determines direction and extent of movement according to user requests, though always prioritising the direction of travel at any given moment. More sophisticated programming can juggle two or more elevators. The latest important idea in this field – a principle known as ‘destination dispatch’ – assigns particular elevators to particular passengers based on the floor they need.

Other innovations – the double-decker carriage that serves two floors at a time; lightweight polyurethane and steel flat hoist belts to replace heavy cables; drives and motors compact enough to occupy the actual shaft rather than a separate machine room – have further diversified the architectural possibilities for tall buildings.

electric drives in lifts elevator technology

Thus the range of the world’s skyscrapers continues to broaden, and to reach new heights. In recent times, it may be noted, China has done more than any other country to drive the industry’s growth: according to the Council on Tall Buildings and Urban Habitat over 60% of 2018’s very tall builds were concentrated there.

Safety, elevators and skyscrapers

But how has this migration skyward changed the experience of living and working in a city? Arguably the most important effect elevators have had on urban existence is that they have made it safer. It is not just that elevators almost never suffer accidents. It is that by allowing cities to grow vertically as well as horizontally, tall buildings have immeasurably curtailed urban sprawl – along with all the miles of road traffic that would have involved.

Sociologically – and ironicallyelevators are a great leveller. In residential buildings, the old class system that saw servants and other low-income citizens relegated to the less accessible upper floors was deprived by the elevator of any architectural correlative. In modern times too elevators promise people of restricted mobility, from wheelchair users to the elderly, the same degree of building access as anyone else.

High-rise living, of course, has always had its critics. Back in the 60s social activist Jane Jacobs saw the tower block as the enemy of the neighbourhood community: you do not pause to pass the time in an elevator as you do on the street corner. And, safe though they are, elevators also inevitably seduce building users away from that basic promotor of physical well-being: the staircase.

The future of elevator technology

However effectively society addresses these and other concerns, technology in the meantime marches on. Elevators, it seems, will soon be able to move horizontally as well as vertically. Thyssenkrupp’s MULTI system will use electromagnetic propulsion to drive cable-free shuttles around building-wide networks of shafts, along floors as well as between them.

The architectural implications are once again significant: elevators may in the future connect spaces between buildings (laterally, like bridges) as well as within them. Shafts, like train tracks, may no longer always have to be dead straight. Under the influence of this technology, skylines might start to look more interlinked, more organic.

So much is speculation. But, if it comes about, such a prospect would be visually consistent with the many ways in which, thanks to increasing system-wide automation the city of the future, is set to function as an intelligent, interconnected whole.

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Automation Engineer

Automation Engineer