Old Wobbly! (The Millennium Bridge)

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Figure 1. The Millennium Bridge from the Tate Modern observation deck.

Why did the public cross the bridge? To get to the other side.

That joke is old news, just like crossing the Thames by foot is old news. The Romans built the first bridge across the river almost 2000 years ago, and the oldest surviving bridge,  Newbridge – dates from the 13th century (South). So how did the Millennium Bridge, something as simple and old-fashioned as a footbridge, draw over 80,000 people to its opening day in 2000? Perhaps location is the answer, as the bridge connects two high profile landmarks: St. Paul’s Cathedral and the Tate Modern Gallery. Then again, Southwark and Blackfriars, two other bridges perfectly functional for crossing the river (as most bridges are wont to be), flank the new site relatively closely on either side. Perhaps the appeal lies in the bridge’s technologically sleek design? The designers touted the project as a “blade of light across the Thames” an emblem of technology at the start of the 21st century that “gives space back to the people” (Foster). Perhaps it was just the novelty of the new. In any case, whether the draw was function or inspiration or something else entirely, the opening of the bridge enticed the modern masses to come out and cross the Thames. So many came out, in fact, that they caused a modern building based on an idea as old as antiquity to become structurally unsound. But more on the unsound bit later on!

First! The Land Before Bridge. The Millennium Bridge connects two distinct neighborhoods that are otherwise separated by that oldest of boundaries, water. In guidebooks, the north side of the river is identified as The City, and the south side is known as Southwark or Bankside (South). Through the middle flows the Thames, a highway neighborhood dedicated to commercial interests from shipping to tourism. On the south side, the land around where the Tate Modern now stands has a history that relates directly to its watery separation from The City. London noblemen of the twelfth century wanted undesirable buildings sufficiently far away from the city center, and a major prison – The Clink – was subsequently constructed on the south bank (South). A number of other socially unacceptable institutions – including the theatres, bearbaiting rings, and houses of prostitution – sprang up in this “Liberty of the Clink,” which was close enough to London to be convenient for those interested, but far enough away to be outside the moral jurisdiction of the City. Southwark became increasingly urban during the eighteenth and nineteenth centuries, giving way to commercial warehouses, manufacturing, iron works and residential tenements (South). Class distinction between the neighborhoods on opposite sides of the river became clearer and clearer, as industrialization and the working classes began to define the south bank while finances, investing, and respectable leisure characterized the north (Tate). The Bankside population reached a high in 1901 before a massive slum clearing project, World War II, and the decline of shipping left the area due for redevelopment. One part of this redevelopment, Mott, Hay & Anderson’s 1960 Bankside Power Station (designed by architect Sir Giles Gilbert Scott of the ubiquitous red telephone box) still stands (South). The Power Station was built on the south side of the river much the way the Clink was built on the south side eight centuries earlier – no one wanted something like that near the City. The Power Station is symmetrical and boxy, and its one striking feature – a tall central chimney smack in the middle – did not challenge the height and grandeur of St. Paul’s (Tate). A 1983 architectural guide gives the building the following description: “the main impression is of the stunning scale of the bare walls of immaculate brickwork, excellently set off by the smooth greensward beside the new riverside walk” (South). The power station and its greensward remain, but the building no longer houses the oil-burning apparatuses of power production: by 1981, the Power Station had ceased to function, and was defunct until 1994, when the Tate Museum, expanding from its Millbank site, acquired the property. The design of architects Jacques Herzog and Pierre de Meuron was chosen for the renovation, and the Tate’s extensive collection of Modern Art now calls the building home (Tate). Herzog and de Meuron’s one and only addition to the outside of the building is a two-story glass enclosure that stretches along the top of the whole of the original structure (please see Figure 2).
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Figure 2. The Tate Modern with two-story glass addition.

This frosted enclosure is bisected by the dark central chimney and is illuminated at night, a “welcoming beacon” that boldly advertises the change from non-descript power station to world-class art gallery (please see Figure 3).
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Figure 3. The Tate Modern at night.

The building promotes itself as a brilliant addition to the physical and intellectual cityscape of London, its square shoulders juxtaposed nicely against the imposing dome of St. Paul’s just across the river.

And indeed, just on the other side of the Thames lies the monument that is St. Paul’s Cathedral (please see Figure 4).
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Figure 4: St. Paul’s Cathedral southern elevation at dusk.

St. Paul’s dates from the eleventh century, and the medieval cathedral was “one of the finest in England.” This medieval building was destroyed in the great fire of 1666, and construction of the present cathedral, designed by the ubiquitous Christopher Wren, began on 21 June, 1675 (City). The main material for construction was Portland stone, which came from quarries opened by architect (and designer for the theatre) Inigo Jones. After 38 years and £722,799, the 1712 Parliament declared the building officially complete (City). The area between St. Paul’s and the river, known alternately as Upper Thames Street, the North Bank, and/or St. Peter’s Hill primarily served the wharves and warehouses along the Thames from 1666 until the mid twentieth century, when World War II broke out and heavy air raid bombing destroyed many of the buildings along the river. Buildings constructed after the war remained rather squat to preserve the view of St. Paul’s, and, as riverside trade was declining, the warehouses gave way almost entirely to the large, low buildings and offices of the 1970′s and 1980′s (City). Nikolaus Pevsner’s 1997 architectural guide to the City of London insists “none of [the new development] is friendly to pedestrians, who may want to follow the riverside walkway where this has been completed. The dedicated traffic-hater may prefer to view the buildings of the South side from the Surrey bank” (City). This tidbit is a clue to the importance of the new bridge and the design competition that was held one year before Pevsner’s critique of the area. The riverside walkway was incomplete, and the heavy traffic made for an unpleasant walking experience. A new bridge designed exactly for pedestrians – no complication or noise from cars, buses, or trains – would make this section of the North Bank pedestrian-friendly and inviting for the first time in decades.

On to the stipulations of the 1996 design competition: connect two landmarks – the Tate Modern and St. Paul’s – and two historical neighborhoods – Southwark and St. Peter’s Hill – with a footbridge made for the masses. In 1996, Sir Norman Foster (Foster and Partners) and sculptor Sir Anthony Caro, with the Ove Arup Firm attached as the engineer, trounced over 200 other entries in the competition sponsored by the Financial Times and the London Borough of Southwark. Their design for the Millennium Bridge met all the design requirements: the footbridge bisected the space between two already-existing bridges, Southwark and Blackfriars, conformed to height regulations dictated by St. Paul’s Cathedral, and was elevated sufficiently to allow Thames boating traffic to pass underneath (Arup). But their design also carried with it the lure of “spiritual design” – in his essay “The Microchip and the Zen Garden,” Architect Norman Foster insists that “function” has two parts: “the chip symbolizes the (…) objective, quantifiable side of the equation [that] is only one part of the equation.” The Zen garden, on the other hand, addresses “the subjective, the needs of the spirit. Why are crowds attracted to certain spaces and places?” (Recent Works). The Millennium Bridge can be seen as a permutation of the two, as the advanced physics of a super-low suspension bridge meet the Zen spirit of a quiet, graceful, “beam of light” across the river. The unique amalgamation certainly attracted a crowd at its opening, and in the end the Microchip wasn’t quite strong enough to support the massive appeal of the Zen Garden. But more on that in a moment.

According to the Royal Academy of Engineering’s dossier, the Millennium design is that of a shallow suspension bridge (other notable suspension bridges include the Brooklyn Bridge in New York City and the Royal Gorge Bridge in Carson City, Colorado). The bridge is unique in that the suspension cables are below the level of the walkway as much as possible (microchip) to allow for unobstructed views of the Tower Bridge to the East and the wide river and banks to the West (Zen garden). The bridge was constructed with concrete foundations, steel beams and cables, and a steel-framed aluminum deck (Linking London). The four groups of cables on either side of the bridge are anchored on both sides of the river to massive reinforced concrete abutments (please see Figure 5).
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Figure 5. Anchored cables under the Millennium Bridge (with student for purposes of scale).

There are 12 piles (posts driven vertically into the ground to support the concrete foundations) in the north abutment of the river and 16 on the south – the difference in numbers is due to the lack of space on the south bank, requiring a shorter and therefore denser “pilecap.” Both the abutments and the bridge’s pair of piers were constructed with ship traffic in mind, and are designed to withstand impact from the largest ship passing through this part of the Thames (Linking London) (please see Figure 6).
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Figure 6. Ship traffic underneath the Millennium Bridge.

The style of the bridge matches function exactly: the sweeping suspension cables (where the influence of Sir Caro the sculptor is clear) reveal the expanse of river on either side, while the north end of the bridge leads directly (and to great effect) to the dome of St. Paul’s Cathedral (please see Figure 7).
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Figure 7. (from top to bottom) View from the pedestrian entrance to the bridge on the south bank; view from the south bank towards St. Paul’s.

The bridge is simultaneously artistic and functional – during the day, Foster’s trademark geometric forms slice across the river (please see Figure 8), and at night, the lit deck leads pedestrians from the illuminated clerestory-esque floors atop the Tate Modern on the south side to the traditional beauty of the spotlit St. Paul’s dome on the other.
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Figure 8. A view of the bridge’s geometric division of the river.

The structure is currently in terrific condition, a real success considering what happened during its maiden voyage across the Thames seven years ago. Drum roll, please…

On June 10th, 2000, the bridge opened to pedestrians for the first time. An estimated 80,000 to 100,000 people came out to celebrate, and suddenly there was a problem: under the massive load of all those folks, the bridge began to wobble, a phenomenon now known as Synchronous Lateral Excitation (a really terrific video of “The Wobble” can be found at http://www.arup.com/MillenniumBridge/). Arup ended up closing the bridge after just two days in order to assess and fix the problem, and a team of engineers determined that the slight sway caused by the heavy load was worsened when people found it easier to walk in tune with the sway than to struggle against it (Arup). The result was a bridge that moved 70 mm side to side when most “excited.” The engineers determined that there were two solutions: either to stiffen the entire bridge considerably, which was an extremely expensive and lengthy process, or to employ some sort of “damping.” Damping is a way of exerting pressure that will control the results pedestrian force had on the oscillation of the bridge, and the engineers had two options: active damping or passive damping. Active damping uses powering devices that exert forces based on detected vibrations. The group chose passive damping, since active damping had never been used on a building as “multimodal” and complex as a bridge. The bridge was therefore equipped with glorified shock absorbers (of course this is a gross simplification) known as “viscous dampers” and “tuned mass dampers” that minimize both sideways and vertical movement (Arup). The modifications were successful, and the bridge reopened, sans wobble, on February 22, 2002 (Linking London).

Today, the Millennium Bridge is a huge success: scores of tourists and locals tramp across it daily, moving from St. Paul’s to the Tate Modern/Globe Theatre and back again. The bridge is sandwiched between Blackfriars and Southwark bridges, but the side-by-side comparison between the Millennium and these two only strengthens the Millennium’s appeal. Sailing underneath, the Blackfriars and Southwark are sturdy, stone, and in some ways sordid: the Millennium, in contrast, is spidery and fine, skipping across the river like a delicate, shiny, spindly-legged water bug (please see Figure 9).
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Figure 9: Side by side comparison (from top to bottom) of Southwark Bridge, the Millennium Bridge, and Blackfriars Bridge.

One can see how Foster was inspired by the “blade of light” that would “shoot across the canyon in the Flash Gordon television series” (Foster). Crossing the Millennium, there is only the sound and sight of other people and the river underneath – no cars or trains or buses distract from the 360-degree views of London and the Thames. And above all, the bridge is public – there is no entrance fee to experience it, no lines, no time limit. One can sit all day and watch the sun rise and set, can cross halfway to see one part of the river and then come straight back, can use the bridge as a pathway for seeing that reveals new views and unobstructed perspectives. The small neighborhoods it leads to, connects, and draws from, sandwiched between St. Paul’s and the Tate Modern, are bright and clean and above all welcoming to pedestrians. There are no vehicles at all between the water and the Tate, and only one major street runs between St. Paul’s and the river (please see Figure 10). The designers have successfully generated a bubble of traffic-without-exhaust and bustle-without-emissions around their Millennium Bridge.
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Figure 10. Clockwise from top right (and all free from motorized traffic): a view of the Tate Modern and Millennium Bridge through a framing gate on St. Peter’s Hill; St. Paul’s and St. Peter’s Hill from the bridge; Bankside riverside walkway (featuring the Globe Theatre) from the bridge; the facade and plaza of the Tate Modern.

In trying to summarize the Millennium Bridge’s mass appeal, it is perhaps easiest to steal from Ezra Pound and his idea of modern poetry: this moment in modern architecture “made it new,” taking an ancient idea and revitalizing it with the technology of a Microchip and the intuition of a Zen Garden.

So why did the public cross the bridge? Because of the bridge, of course.

WORKS CITED

The Buildings of England: London 1: The City of London. (cited as “City�) Ed. Nikolaus Pevsner. Great Britain: Penguin Books, 1997.

The Buildings of England: London 2: South. (cited as “South�) Ed. Bridget Cherry and Nikolaus Pevsner. Great Britain: Penguin Books, 1983.

Foster Associates: Recent Works (Architectural Monographs No. 20). (cited as “Recent Works�) Introduction by Kenneth Powell. Great Britain: Academy Editions, 1992.

Foster, Peter. “Blade of light bridge dazzles all who gaze upon it.� The Telegraph 8 Jun. 2000: issue 1840.

Linking London: The Millennium Bridge. (cited as “Linking London�) Ed. Tony Fitzpatrick. Ove Arup Partnership. London: Royal Academy of Engineering, 2003.
“The Millenium Bridge.� (cited as “Arup�) Arup Group Ltd. http://www.arup.com/MillenniumBridge/index.html 29 Jun. 2007.

Tate Modern: The Handbook. (cited as “Tate�) Ed. Iwona Blazwick and Simon Wilson. Great Britain: Trustees of the Tate Gallery, 2000.

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