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Bridges FACT FILE A1 Peterborough to Blyth upgrade Main client: HIghways Agency Structural engineer: Atkins Main contractor: Interserve Steelwork contractor: Fairfield-Mabey Steel tonnage: 900t Project value: £83M long bridge is being constructed over the existing the scheme and again involve new steel bridges to A1 with new roundabouts either side. replace at grade roundabouts. In fact Colsterworth Interestingly at this location an innovative and will require two steel bridges, one for the junction time-saving procedure has been used for bridge and another which will replace a troublesome A1 construction. In order to reduce disruption and cross-over. speed up the works process, the new bridge was Using steel for the new bridges has brought fabricated on an adjacent site, at the same time as a number of benefits to the project according to the abutments were being built. Once both were Interserve. “We have saved time by using near-site finished the bridge deck was transported as one fabrication and steel certainly lends itself to this kind large structure, over a distance of 200m, and jacked of construction,” says Mr Abraham. “Plus, for these into its final position. 30m span structures steel is a more economical While the bridge abutments were being readied, material.” The new bridge was steelwork The other three steel bridges on the A1 project contractor are being erected in a more traditional manner. fabricated on an Fairfield-Mabey Directly south of Blyth, the Apleyhead A1/A614/A57 adjacent site at the same was busy bridge has been completed and open to traffic since assembling the October 2007. time as the abutments bridge steelwork At this junction a new dual carriageway for were being built. platform to the existing A1. New southbound on and off slip roadsthe A1 was constructed in fields to the east of theon a temporary side of the new bridge position. The composite steel were built, and the new bridge connects the existing Above right: Multi-axle SPMTs and concrete deck consists of six longitudinal steel roundabout with a new western roundabout, lifted, carried and jacked the beams, each 1.2m-deep arranged in three braced completing a new dumb-bell shaped junction. completed steel bridge into position. pairs forming a 30m-long, 13.5m wide structure. It As the new bridge was constructed over a new was assembled 1m above grade and this also had road, traffic disruption wasn’t an issue, but all bridge the benefit of minimising working at height. beams were still delivered to site by Fairfield-Mabey Once the entire bridge deck was assembled, at night, to minimise congestion. along with the concrete decking and edge Likewise, the works at the Gonerby Moor A1/ protection, the lifting, jacking and transportation B1174 junction, which includes site clearance, top- process was undertaken to transfer the structure to soil stripping, bulk earthworks and bridge construc- its final position. tion, have also had limited impact on the existing A1 “Luckily there was enough space close to the as the majority of work has been carried out off-line. bridge to construct the deck,” comments Richard Markham Moor, the A1/A57 junction, has proven Selby, Project Manager for Fairfield-Mabey. to be the most complex. The new steel bridge has “Interserve didn’t want to transport it too far in been constructed in the middle of the existing order to minimise time and any potential damage to roundabout, with live traffic circulating around it the bridge.” both day and night. Interserve employed heavy lifting specialist Once complete the new A1 will run right through Mammoet to carry out this procedure. This the Markham Moor roundabout with new junctions technique is rarely used with a steel bridge deck either side of a new over bridge. After the bridge in the UK, but Interserve reckons it reduced the abutments were constructed Fairfield-Mabey The Markham Moor bridge construction programme at Blyth by approximately brought the steelwork to site and erected braced is being constructed on a two months. beams in pairs. busy roundabout with heavy The fully assembled deck weighed 550t and to “It’s the location which makes this bridge so com- traffic circulating around it move this huge section into place Mammoet used plex,” says Mr Abrahams. “Getting the equipment continuously. its self-propelled modular transporters (SPMTs). and materials to site has been challenging. These remote controlled multi-axle units transported But if the bridge was built with concrete we the deck, over the recently levelled ground, to would have had twice as much traffic and materials its final position were it was then jacked up and going to site, adding to an already busy and at times lowered on to the abutments. congested junction.” In the end the whole transportation and jacking Keeping disruption to a minimum during the process was completed in one night time operation. works, with the least amount of closures and contra- “The whole process went very well,” comments Mr flows, is key to the whole scheme. “Using steel and Abraham. So well in fact that a similar operation utilising the SMPTs has ensured we’ve met this will be carried out at the Colsterworth A1/A151 and target,” sums up Mr Abraham. Carpenters Lodge A1/B1081 junctions in April. All six junctions are scheduled to be completed These two junctions are the most southerly in by October 2008. 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