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The Clydesiders' choice for a new foot crossing

ROADS & BRIDGES

IT MIGHT not have an official name yet, but already it has proven its popularity with the people of Glasgow, writes Diarmaid Fleming.

The winning Neptune's Way entry for a new footbridge across the Clyde, linking Broomielaw and Tradeston across the river won the approval of the public when all six entries in a competition held by Glasgow City Council were put out to public consultation in late 2003.

The competition had six final entries and, while a technical panel assessed each, a public consultation was also run with people invited to sketch their own favourite bridge on a picture of the site.

'There is always a worry for politicians with a consultation like this ? the public only has to look at things aesthetically and theirs is sometimes the dearest solution or the most technically difficult. But in this case, the technical group's choice and the people's choice was the same, ' says the project director, Iain Macnab, Glasgow City Council's head of environmental services for development and regeneration.

As well as bringing neglected areas of Glasgow closer to the city, the bridge is bringing together some of the brightest brains in construction design and architecture. The winning team is made up of architect Richard Rogers Partnership, engineers Atkins and project/cost managers Faithful and Gould.

The success of Gateshead's Millennium bridge has not gone unnoticed in Glasgow. But any suggestion that the winning entry ? a stunning cable-stayed compression arch and suspended deck, curved both in plan and elevation ? may look a little similar to famous Geordie 'blinking eye' structure could risk an outburst of sharp Glaswegian from those close to the project. To the casual observer it may bear similarities but it is an entirely different structure.

'Gateshead made a huge public impact but there this is a different bridge completely. It's a fixed bridge, whereas Gateshead's Millennium Bridge has to move to let ships through. Theirs is a more traditional balanced arch, whereas ours is cantilevered, ' says WS Atkins design manager Drew Page.

The bridge spans 90 m but the large elliptical arc shape of the deck is 180 m in length, the form giving a sense of the bridge being drawn by the river current. This makes it accessible to all users, the 1 in 20 gradient across the bridge traversable without the need for steps or lifts at the ends. The deck consists of a steel torsion box, from which cantilevers a separate cycleway.

Cables suspend the deck from the arch, which in turn is suspended from two stays anchored on each bank opposite the deck side. The arch itself ? 1,200 tonnes of steel ? varies in section with some simple but ingenious fabrication: four cut circular hollow segments are connected with long flat plates: the flat sections taper in width to vary the arch section, giving the seamless, elegant appearance.

The bridge can accommodate 5,000 people and widens to 7 m at midspan to create a substantial space. Fears that it might wobble like London's Millennium Bridge are dampened, literally.

'The elliptical arc form of the deck mitigates against a dynamic wave propagation along the br idge as happened in London, ' says Mr Page.

But with plans to hold musical or artistic events along or beside the river with the bridge as a viewing platform, or even events on the bridge itself, with large crowds dancing on it, would have to be managed to prevent any unwanted dynamic effects. Wind tests have been carried out by BMT Fluid Mechanics.

A team f rom across the UK is involved in the br idge scheme, co-ordinated by Faithful and Gould regional director Gordon Reid.

'It is such a unique project, rather like several projects in one, ' says Mr Reid. 'And it requires management of a diverse team. Richard Rogers Partnership came up with the concept in conjunction with Atkins, and now the team is bringing that concept to reality. Dealing with a large client with different interests in the project is another challenge.' Major piling works for the bridge foundations and to the quayside are involved, while the £34.5 million contract also includes substantial 'public realm works' to improving the quayside with high-quality public spaces. Flood prevention will also benefit from the work. The bridge, which comprises around £15 million of the contract is currently out to tender. It is hoped that work will start at the start of 2006.