THE MILLENNIUM DOME at GREENWICH
af Royston Landau, december
Even though the media was completely negative about the Millennium Dome it
was an engineering breakthrough and it contributed to the regeneration of a
huge brownfield area in Greenwich.
The Millennium Dome at Greenwich (Fig.1) has a history, which begins in 1994 when the Conservative Government
proposed that the new Millennium should be celebrated with an Exhibition. The 1951 South Bank Exhibition and earlier the great 1851 Crystal Palace Exhibition had helped to create a tradition for such a celebration.
By 1996 a new Labour Government had replaced the Conservatives and Prime Minister Tony Blair accepted the project, which by this time was proceeding under a Government appointed Millennium Commission. A key issue to be
decided was where such an exhibition should be located and a promising site had been identified on the tip of the Greenwich peninsula. It was a 120ha area of wasteland surrounded on three sides by the River Thames and located on the 0 degree Meridian.
This location was five miles to the east of Westminster and central London.
Although the site was a conspicuous location visible from both sides of the River and especially from the north, access to it by road was difficult. This was because at the tip of the peninsular there existed the heavily used Blackwall Tunnel road system with the Exhibition site being over a part of this system. To reach this site by boat along the Thames from central London would be direct and simple and it would be expected that good beating services could be organised. But by far the greatest number of visitors would be expected to use the new extension to the Jubilee Line Underground train services, then under construction. The Underground opening date was due before the start of the Millennium Exhibition.
The site itself had earlier been a Gas Works, which had been abandoned for more than twenty years. It remained heavily polluted so the possibility of rehabilitation such a well positioned contaminated (brownfield) site added to its appeal. But the story of the politics and the development of the project involving many parties is highly complex, although here, I will focus mainly upon the design and the designers of the Dome.
Three design firms played a major part in the "Dome" concept. The first was Imagination, which had been appointed by the Millennium Commission to find a suitable site and to design the exhibition. The Greenwich peninsular was one of the sites for consideration. Imagination's early ideas included an exhibition with an open arena enclosed by twelve separate pavilions each with an air-balloon, which could travel around England before returning to Greenwich.
The second firm, the Richard Rogers Partnership was separately appointed to prepare proposals for the development of the Greenwich peninsular but also to contribute to the regeneration of the whole area. Under Partner Mike Davies, a collaboration developed with Gary Withers of Imagination, the outcome of which was a proposal for a single large umbrella structure, which could house the total Millennium Exhibition. Such an idea had certain similarities to the earlier Imagination twelve-pavilion project (without the balloons!), since it was organised using a twelve-mast support system, with each mast providing a location for an exhibit. But just how to cover a single 80,000m2 space provided a major engineering challenge, which would entail designing the largest enclosed covered space ever. At this point the third major design firm, Structural Engineers Buro Happold, represented by Ian Lidell was brought into the story.
It must be mentioned that the project from its very beginnings was under pressure from an unsympathetic and frequently hostile Press/Media. Doubts were expressed about its funding (it was funded by Lottery money and Private Companies), about its location, about whether it could be built on time? It was accused of being a waste of money! (just as the Crystal Palace had been) - altogether appearing to be attempting to provoke public hostility. Nevertheless, the preparations for the first stages proceeded and by 1997 the Government decided that the Exhibition building should be built to have a life-span of more than one year.
So a new building emerged, spatially simple, although not a "dome" in the structural sense (i.e. not a compression structure). Rather it is a lightweight tension structure built to a spherical profile (Fig.2). In size it has a diameter of 320m, an internal height at the centre of 48m, covered by two layers of long-life PFTE coated fabric, which is dirt resistant and will not discolour. The double skin also reduces the possibility of condensation. Such a fabric has a high light transmission factor, good for daylight illumination of spaces and exhibition displays. The PFTE coated fabric will also, if required, be capable of meeting the needs of a long life span.
This layered fabric roof with a 30m ring at the centre is held together by a radial tensioned cable system which controls deflection but also provides locations from which the roofing is tied to the towering twelve masts both at the top and at the bottom. The masts, made from steel tubes (Fig.3), are 90m long and each sit on a 10m high steel base, so allowing at each junction any movement which might be caused by wind, rain or other forces. From the tips of the masts hangs the tensioned steel cables, arranged to connect with the tops of the radial cables, which define the spherical shape of the roof cover. On the under side of the roof there are tie-down cables connecting to the base of the masts and altogether providing a tensional system designed to possess sufficient surplus so that the failure of a single mast cannot affect the safety of the whole structure. Both the mast bases and the edges of the roof skin are tension cabled to a series of concrete anchor points, which surround the perimeter of the dome (Fig.4).
In the overall site layout, there are many small complementary structures including canopied walkways (Fig.5), a floating jetty and Urban Studio's Skyscrape cinema. All share a similar cladding system to the Dome.
In the west side of the roof there is a 50 m diameter opening to allow the Blackwall Tunnel air vents to pass through. This is required by law.
It is widely acknowledged that the design and construction of the Dome is a highly significant and contributive achievement. The design and organisation of the Interior Exhibits however is not of the same order. An account of the sponsoring, the organising and the problems of co-ordination would be a long story, which cannot be told here.
While the negative media response to the Greenwich enterprise will have influenced the numbers of visitors and therefore the eventual income related to costs of the enterprise, statistical accounts on visitor satisfaction report that nearly 80% regarded it as a highly enjoyably and memorable experience.
But also to be acknowledged are the benefits gained by the town of Greenwich through the upgrading of the area and by the numbers of visitors being newly introduced to a location, which was already one of the great historical and museum sites of London.
At the time of writing, the Dome Exhibition closes on December 31st 2000. After this the Dome structure will become a new High-Tech Business Park with the name "Knowledge City".
The story will continue...........
The official Millenium Dome website: www.dome2000.co.uk
Aerial view of Millennium Dome at Greenwich
Isometric of Dome showing the cable support system
Steel masts. Engineer Drawing
Perimeter of Dome. Cable fixings
Floating jetty showing canopied walkways
Figs.2 & 4 Buro Happold Structural Drawings.
All illustrations from "Architecture Today No.111"