Bridges: A1 Leeming to Barton upgrade

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Bridging the A1 gap Eight steel composite bridges are being installed as part of the A1 upgrade in North Yorkshire. Kneeton Hall Accommodation Overbridge Kneeton Lane Overbridge Brompton North Underbridge Brompton South Underbridge Agricola Underbridge Fort Overbridge Catterick Darlington Scotch Corner Leeming Sowber Hill Bridges Accommodation Overbridge Low Street Overbridge A1 A1 A1 (M) A1(M) A66 (M) A66 River Tees River Swale As the only section of nonmotorway on the strategic M1/ A1(M) route between London and Newcastle the busy 12-mile section between Leeming and Barton in North Yorkshire is being upgraded from a dual carriageway into a three-lane motorway. Once completed the scheme will unlock growth and boost the economy by creating a continuous motorway-standard route that will also improve journey times and increase safety. This stretch of road carries approximately 69,000 vehicles every day and, according to Highways England, it is not entirely fit for purpose for today’s traffic volume. It suffers from poor alignment with numerous side roads and minor lanes entering and exiting, which has contributed to the accident severity ratio being significantly higher than for other similar roads. A major part of this project is the construction of new bridges that either span the widened road or carry the new highway over streets and rivers. Eight of these new bridges are steel composite structures and they are being fabricated, supplied and erected by Cleveland Bridge for the Carillion/Morgan Sindall JV. The project’s structural engineer is Aecom, and its Principal Engineer Peter Robinson explains the choice of materials for the bridge’s design. “We had to look at a number of criteria when choosing which materials to use for each bridge. Steel was used for the longer span structures because it is lighter than other materials and so more cost-effective, while another important factor was installation and getting materials to site. Steel beams and components are generally fabricated offsite and then quickly assembled and erected on site, which causes minimal disruption.” All of the steel bridges were modelled in 3D using the Autodesk Revit programme. This was then inserted into a BIM model, which proved to be critical for providing toolbox talks on site and to help the various trades carry out clash detections. The longest steel bridge on the scheme at 86.5m and the one with the biggest steel tonnage at 398t is the Kneeton Lane Overbridge, which is located just north of Scotch Corner. This structure consists of two spans supported on reinforced earth abutments that have been squared up to allow for a semi-integral form of construction. The central pier however is skewed to follow the alignment of the A1(M) below; this results in asymmetrical spans. “The bridge was checked for lateral torsional buckling in the temporary condition using the analysis package Lusas. Because of the skewed pier, significant twisting occurred in the model which led 16 NSC July/Aug 16 FACT FILE Bridges on A1 Leeming to Barton upgrade Main client: Highways England Main contractor: Carillion/Morgan Sindall JV Structural engineer: Aecom Steelwork contractor: Cleveland Bridge Steel tonnage: 1,431t


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