TPi July 2009

developments products &

in 45 separate loads. However, once erected it was able to lift the 230 tonne superstructure element of the footbridge into position using a single operation that commenced at 8.30pm. Once the new bridge was successfully located and secured into the support structure, the lifting slings attaching the bridge to the crane were removed and the motorway was re-opened at 3am the following morning – some three hours earlier than planned – ensuring that closure of the motorway was limited to one evening.

essentially giving the architect greater design scope. In addition, the off- site fabrication associated with steel ensured that delivery of the project incurred minimal disruption on the locality through road closures – which in itself created significant economic and health and safety benefits.” Raynesway Construction carried out the complex operation to install the main superstructure section of the footbridge using one of the UK’s largest cranes, complete with a 90-metre job and 600 tonnes of superlift counterweight. The crane itself took a week to assemble, having been delivered to site

and qualities of structural hollow steel sections, both in its delivery and its long-term performance. Twelve circular hollow sections supplied by Corus Tubes wind around the outside of the structure to create the signature corkscrew-like appearance, with the slender lines of the curved steel tubes and the neat welded joints ensuring the sharp lines of the structure’s design could be achieved. The elliptical structure provides an enclosed crossing, which is fully glazed with polycarbonate panels, ensuring a safe and comfortable environment for pedestrians and cyclists using the bridge. All the steel components were subject to a rigorous testing regime, first by Corus Tubes during manufacture of the steel sections at its Corby mill, then by SH Structures. SH Structures, used to working on com- plex tubular steelwork, pre-fabricated the sections at the company’s facility. As well as reducing the amount of work that actually took place on-site, off-site fabrication of the sections in the closed factory environment meant work was unhindered by prevailing bad weather conditions that might have otherwise caused delays on the exposed site. The relatively low weight of the structural steel components enabled sections to be easily transported to the site, where the only work required was the welding of the splices to create the complete 90-metre span. TimBurtonof SHStructures commented, “ The complex design and fabrication of the bridge meant that the footbridge components needed to be carefully pieced together – an intricate process that was facilitated by the unique properties of steel which allowed it to be easily bent and shaped. This enabled it to be designed to a range of shapes that were easy to construct,

Corus Tubes – UK www.corustubes.co.uk

The bridge was lifted into place in one ▼ ▼ night

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July 2009 Tube Products International