A bridge too far? Not for A&J
Beam and girder fabrication for buildings and bridges is usually considered as ‘bread and butter’ to A&J Fabtech whose design and engineering teams are used to working to standards such as BS5400 for steel, concrete and composite bridges. Every now and again however, this sort of work throws up a challenge, such as the Hungate Road overbridge ordered for Network Rail.

The contract, for Britcon as sub-contractors to project leaders May Gurney, was for 4 beams that would form the main load-bearing structure of a road bridge over the Peterborough to Nuneaton section of the main Network Rail East – West rail link. Each 30 metre beam would be made in three sections spliced together with over 250 bolts per splice.

To complicate matters the bridge crossed the rail line on the diagonal, so the bridge structure would resemble a parallelogram with a 45 metre span across the diagonal. In addition, the bridge would be assembled, complete with road deck and then lifted into position as a finished construction – all 80 tonnes of it! It was the complex angled form of the finished construction and the criticality of achieving an exact fit that lead the project contractors to A&J and their expertise in this type of large scale precision fabrication.

“With on-site assembly and the final lift of the completed deck into position over the rail line scheduled for a two day window, Network Rail were keen to have a trial assembly to ensure that all the careful design calculations would translate into the perfect finished structure. With our purpose-built indoor craneage and large work bays we were able to carry out the trial assembly quite easily, allowing Network Rail’s inspection team to confirm everything was to specification, commented Sam Shaw, project co-ordinator for A&J Fabtech.

Following the successful trial assembly the fabrications were painted and delivered to site, where on the weekend of May 8/9, the framework was assembled, complete with road deck, walkways and guard rails and lifted into position, locating perfectly onto its pre-prepared foundations.