Though we may take them for granted today, the advent of the elevator in the 19th Century
transformed the way we live our lives.
Revolutionising building design, disrupting established conventions, shaping our cities
and making our vertical world viable, elevator systems have continually helped engineers
and designers raise the roof of structures
from the early skyscrapers of the 1800s
to the incredible projects of today, that push the very limits of construction capability.
But what drove their original invention? How did the first elevators work? How have they
evolved to support the extreme height of some of today’s most impressive projects
and how will they support the vertical cities of the future?
This is the story behind a relatively simple innovation, that is continuing to shape our world.
With land more freely available and stairs as the only means of vertical access, there
was little to drive the construction of high rise structures before the 19th Century.
As such, tall buildings were largely limited to military and religious structures that
used their height for strategic or ornamental purposes.
The upper levels of buildings were widely deemed to be undesirable, while lower levels
– with easy street access and few stairs to climb – were the preferred domain of
wealthy residents and businesses alike.
Additionally, the practice of building with external load-bearing walls caused structures
to thicken at their bases as they grew taller, reducing floor area on these desirable lower levels.
With the dawn of the industrial revolution, urban areas began to grow substantially and
the demand for space increased.
Faced with a growing dilemma, pioneers began considering alternative means of vertical access.
Though simple elevators had existed for many centuries, these early devices consisted primarily
of a platform suspended by a rope and pulley system which was lifted by an animal or by manpower.
These devices were only used for moving individuals or goods over short distances due to their
slow speeds and the risk they posed to human life in the event of a cable failure.
At New York’s World’s Fair in 1854, Elisha Otis presented the world’s first vertical
mobility platform capable of stopping, rather than falling, in the event of its main cable breaking.
Otis achieved this by designing his elevator with a mechanism between the cable and the
elevator car consisting of two levers.
When the cable is under tension these levers retracted away from the sides of the elevator
shaft and allowed the car to move freely.
However, if the cable broke – releasing its tension – springs behind the levers
would force them outwards into grooves in the elevator rails, those rails were then
forced against the shaft walls, quickly arresting any cars fall.
The success of Otis’ demonstration at the World’s Fair prompted a flood of orders
from developers.
At the same time, architects and engineers were beginning to use steel in their building
superstructures enabling projects to be constructed with thinner, more lightweight walls.
The combination of Otis’ invention, together with the increasing popularity of this new
material began to have a transformative impact on building design, shattering the negative
preconceptions around tall structures and opening up a new vertical frontier.
As the early boom in skyscraper construction occurred in the United States, elevators were
also adopted in buildings of all shapes and sizes around the world.
In Paris, the construction of the Eiffel Tower for the 1889 World’s Fair presented unique
challenges in moving people up and down the structure’s steeply inclined legs.
To overcome this, double-decker elevators powered by a hydraulic ram were installed.
As the elevator car moved up the tower, an operator would adjust the pitch of the floor
to ensure passengers remained horizontal.
Indeed, many of these early elevators were supervised by lift operators and primarily
powered by steam or hydraulics.
Despite being developed and available to install from around 1900, fully automatic lifts proved
widely unpopular as – rather like today’s driverless cars – the automated operation
of such a sophisticated device was a cause of concern to many.
It wasn't until 1945 – with an extended operator strike and the introduction of both
emergency stop buttons and telephones within elevator cars – that automated systems became
widely adopted.
As the 20th Century continued, new technologies emboldened architects and engineers to design
ever-more elaborate tall structures.
Seattle’s Space Needle was constructed for the 1962 World’s Fair, while in St Louis
the 192-metre “Gateway Arch” was erected, marking the city’s status as the gateway
to the west.
Chosen from a design competition in 1947, the arch was to contain an observation deck
at its summit – posing a considerable challenge to conventional elevator systems.
The arch’s solution operates more like a vertical tramway, with visitors entering one
of eight horizontal compartments which proceed up one leg of the arch along curved tracks.
Starting the journey hanging from guide rails, the capsules remain upright by tilting in
the opposite direction as they rise, maintaining a level orientation during the trip to the top.
The first half of the 20th Century also saw Paternoster elevators installed in many structures.
Formed of a constantly moving chain of boxes that passengers could step in and out of – the
systems were initially very popular in buildings where large numbers of people frequently moved
between floors.
However, with elevator cars moving very slowly and numerous instances of passengers becoming
crushed or losing limbs, Paternosters were phased-out by the 1970s and less than 300
examples remain in operation today.
With an economic boom in the 1960s, demand for space in some of America’s largest cities
once again increased.
While building taller structures on available sites was a logical way to increase floor
area, architects and developers faced the challenge of providing sufficient vertical
access for occupants without the increased number elevator shafts reducing lettable floor
areas to the point where schemes became unviable.
This challenge was overcome in designs for New York’s original World Trade Center towers
– structures that became the tallest buildings in the world when they were first constructed
in the early 1970s.
By “stacking” elevator shafts and introducing “sky lobbies” passenger capacity could
be increased without increasing the number of shafts on the floor plate.
Under this system, occupants would disembark at a sky lobby floor, before entering another
elevator to continue their journey.
The formation freed-up considerable amounts of lettable floor area, particularly on the
higher value upper levels, yielding greater returns for developers.
A variation of this system can be seen in “express elevators” – where an elevator
only serves a dedicated number of floors, improving service and speed for passengers
while reducing the overall number of shafts required in a structure
the system in London’s One Canada Square, is a clear example of this in practice.
In a similar vein, double-decker elevators have also come to prominence, particularly
in cities across Asia and North America.
In a double-decker system, occupants are typically separated by escalators as they enter the lobby.
Those heading to even numbered floors travel in the upper car, while those seeking
an odd numbered floor taking the bottom.
This again increases passenger capacity without conceding valuable floor space to additional shafts.
With the advent of these elevator systems, and with their continued improvement over
time – the fastest installations now able to travel at up to 20 metres a second, and
the free-fall of cars an almost impossible occurrence – working or living a quarter
of a kilometre above street level has become a convenient reality in cities around the world.
With the global population continually expanding – and with people increasingly living in
cities or major urban areas – engineers are today pushing the very limits of tall
building design.
The first decades of the 21st Century have witnessed the construction of some of the
tallest structures ever conceived.
While the finishes, speed and safety features of elevators continue to be improved and have
generally kept pace with the advancements in skyscraper construction, the principal
of an elevator car, suspended by a cable and moving vertically inside a static shaft has
remained largely unchanged for over 160 years.
With plans for a number of towers that will reach or exceed a kilometre in height now
under consideration and even entering early development in some instances – elevator
engineers are approaching the limits of steel cable capabilities and are being forced to
innovate once again.
Electromagnetic elevators, rather like maglev trains, move their passenger cars by electromagnetic
propulsion, negating the need for a cable altogether whilst being able to travel at
increased speeds and with reduced vibration.
They have also created an opportunity for
elevators to move horizontally through a building.
Developed by ThyssenKrupp these “horizontal elevators” run on tracks and are capable
of moving up and down, as well as sideways across a building.
This method enables a continuous flow of elevator cars to operate within a single shaft – with
all cars travelling in the same direction without fear of collision.
While no functional system of this type currently exists, the East Side Tower project in Berlin
is set to become the first project in the world to feature this technology when it completes
in 2021.
Alternatively, externally mounted elevator systems could see elevator shafts disappear
completely – creating more space within structures and heralding a new age of architectural design.
These “Skypods” conceived by PLP Architecture also employ magnetic levitation, but with
passenger cars mounted to tracks on a building’s exterior.
This system would operate in a similar way to a rail network, with tracks curving across
a building’s façade and branching-off to reach destinations where required before returning
to the main loop.
As cars move around a structure, their occupants would remain upright through the use of a gyroscope.
Despite making for a potentially terrifying experience, this concept could liberate engineers
and designers from the existing conventions of vertical design and see a new generation
of freeform towers appear across our cities.
A simplified though no less impressive version of this idea was incorporated into Foster
+ Partners’ design proposal for The Tulip – a 305 metre observation tower in London.
From their humble beginnings, elevator systems have continually played a critical if somewhat
understated role in shaping the world we live in
and with such incredible innovations
ahead, their seemingly perpetual upward journey looks set to continue into the future.
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