Troubled bridge over water: The London Millennium Bridge

Q. Will the wobbly Millennium Bridge ever reopen

A. According to the Press Office of Ove Arup, the contractor for the project, the bridge will reopen 'by the end of the year [2001]'. You heard it here first.

Q. What went wrong

A. Two days after being opened by the Queen, the London Millennium Bridge was closed on 12 June 2000 as it became clear that the structure was swaying more than was comfortable for pedestrians and people were becoming somewhat alarmed. Around 150,000 people had crossed the bridge over the weekend of 10-12 June last year, but the decision was taken to close it at 10pm on the Sunday, after 'greater than expected movement' (quoted from Arup's Millennium Bridge website, see below for details) of up to 70mm was measured.

Q. What's the story

A. The Millennium Bridge is London's first new river crossing in more than a century. The last one was Tower Bridge in 1894. Although the present London Bridge, the third, was opened as recently 1972, it is on the site of the original bridge, which dated back to the Roman city, and as such is not a 'new' crossing.

At the cutting edge of technological know-how, the bridge uses 'lateral suspension', an innovation that allows suspension bridges to be built without tall supporting columns. Eight cables, four on either side of the deck, dip just 2.3 metres over the 144 metre central span. The 330 metre-long pedestrian bridge, which the designers promised would be 'an absolute statement of our capabilities at the beginning of the 21st century', links the City and St Paul's cathedral on the north bank of the Thames with Tate Modern, the new gallery of modern art in the old Bankside power station, on the south.

Q. Who designed it

A. It was designed by Foster and Partners in collaboration with sculptor Anthony Caro and engineers Arup, so there's plenty of experience there. Described as 'a blade of light', the single sweeping arc appears as a thin ribbon of steel by day and, illuminated at night, as a shining tongue of light across the river. It is, indeed, an elegant and thoroughly modern structure, and, at least aesthetically, those behind it have every right to be proud of their achievement.

Q. Who paid for it

A. The bridge is a Millennium Commission project (who provided 7 million of the total bill of 18 million) and it was also funded by the Corporation of London, HSBC - whose headquarters in Hong Kong Norman Foster also designed - the Cross River Partnership and a number of private donors.

Q. How is the problem to be resolved

A. After considering various options - such as stiffening the structure, limiting the number of people allowed on the bridge at any one time and modifying how people walk with the use of street furniture - it was decided that the use of dampeners was the best solution. Essentially giant shock absorbers, these would limit the degree to which the structure was subject to external forces. This isn't as radical as it sounds, as such dampening mechanisms are commonly used in bridges and buildings in earthquake zones.

Q. Any statistics

A.

Length: 330 metres

Width: 4 metres

Height above river at high tide: 10.8 metres

Handrail height: 1.2 metres

Piers: concrete and steel

Cables: 120mm locked coil

Decking: Aluminium

Handrail: bead blast stainless steel

Construction cost: 18 million

Modification cost estimated: 5 million

Q. What is it with Millennium projects

A. It seems to be a London problem, what with the Dome and the fact that the London Eye had to close for modifications soon after opening - although the Eye is, in truth, one of the great success stories of recent years in London. Other bridges commissioned to mark the Millennium, such as the one in Newcastle-upon-Tyne, have not suffered similar fates. However, once it's been fixed up the new London bridge will be a striking addition to the fabric of the city.

For more details on the Millennium Bridge go to

http://www.fosterandpartners.com/projects/0953.html

http://www.arup.com/millenniumbridge/

http://news.bbc.co.uk/hi/english/static/in_depth/uk/2000/millennium_bridge/default.stm

See also the article on the London Mayor's building

For more on Arts & Literature click here

By Simon Smith