The Eiffel Tower

Classic Projects: Eiffel Tower

Immortalised in countless movies, the Eiffel Tower is the most identifiable of French landmarks and one of the icons of 19th century structural engineering

When the Eiffel Tower graced the opening of the 1889 Exposition Universelle World's Fair it was the tallest building on Earth. Standing at 300m it almost doubled the height of the Washington Monument, the previous holder of the record. In the 1950s the Eiffel Tower grew an additional 24m, allowing it to overtake the Chrysler Building and once more claim the title of tallest freestanding structure on the planet.

French structural engineer Gustave Eiffel's tower was designed to be rapidly dismantled within two decades of appearing on the Parisian skyline. But its success as a tourist attraction, along with its utility as a mast for housing telecommunications technology, meant that it survived several attempts to decommission and relocate it.

Given that it is today regarded as one of France's greatest examples of Expressionist structural art, it is somewhat surprising that the tower was so badly received. Leading anti-tower novelist Guy de Maupassant took lunch there every day, claiming that it was the one place in Paris from where he could guarantee he'd not have to look at it.

Project briefing

On 2 May 1886, the French government announced a design contest. French engineers and architects were invited to 'study the possibility of erecting on the Champ de Mars an iron tower with a base of 125m square and 300m high'. The structure needed to be self-financing – able to attract sufficient ticket-buying visitors to recover construction costs – and the design had to allow for easy and rapid deconstruction. The race was on to build the world's tallest freestanding structure in order to become the flagship exhibit at the 1889 World Fair.

Budget and costs

At the time the total build and materials cost of the Eiffel Tower was 8 million francs or $1.5m (around $36m in today's money), but this is not a true reflection of what it would cost to build today, as the labour costs alone (assuming it could be built in two years) would swallow $30m. With a capacity potential of 10,000 fee-paying visitors on the tower at any one time, costs were recovered in the first year of the tower being open to the public, with Gustav Eiffel becoming a rich man as a result.

Personnel

The tower was riveted together by 300 on-site workers. During the course of the project only one worker died. Today, the principal maintenance task is repainting the structure, which must take place every seven years. There is 220,000m2 of iron lattice surface area that needs to be cleaned and painted. Paint must be applied manually, by brush, as rollers and paint guns are not allowed. Each repainting, by 25 painters working for 15 months, requires 1,500 brushes, 5,000 sanding disks and 1,500 sets of work clothes.

Materials

The tower's iron pieces (none weighing more than three tonnes to allow for the use of the tallest available cranes) were cast off-site to allow for rapid construction. Perhaps Eiffel's only mistake was to not galvanise the components before painting. Based on today's wage and price levels, this would have saved at least more than half the construction and erection costs over time. In his defence, Eiffel could hardly have foreseen the longevity of the tower.

Design

Eiffel was one of the first engineers to recognise the importance of wind forces on tall structures. The open sides of the tower mean that the wind passes through the building, which sways only 6-7cm (depending on ambient temperature, thermal expansion may cause the top to shift up to 18cm away from the side facing the sun). This economy of design means that the metalwork of the structure weighs only 7,300t, which if melted down would fill the 125m2 base to a depth of only 6cm.

Facts and figures

If you wanted to build your own Eiffel Tower you'd need 18,038 separate pieces of 'puddled' iron and two-and-a-half million rivets. Once complete, to paint it you'd need 50t of the stuff and the job needs to be repeated every seven years. Although it looks plain brown, several colours are used to create a 'soft-fade vignette' to maintain the optical illusion of tonal uniformity from top to bottom. On a clear day you can see a distance of 42 miles from the top of the tower.

Delivery and legacy

Built in 21 months the tower was delivered on time. In 1889 Thomas Edison visited it and wrote in the visitor book to the 'engineer, the brave builder of so gigantic and original specimen of modern engineering from one who has the greatest respect and admiration for all engineers'. Within a century the tower became the most visited public landmark in the world, spawning more than 30 imitators worldwide, including the Blackpool Tower, an approximate half-scale replica. In 2007 international archery champion Erika LaBrie 'married' the Eiffel Tower in a so-called objectophile union, to become Erika Eiffel.

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