Roberts & Sale Construction (UK) Ltd, a leading supplier in both steel and civil construction works, has successfully delivered the repair, refurbishment, and modernisation of Checkleys Bridge BBM/8. The overbridge, which crosses the Bletchley-Bedford Midland line, is a three-span metal structure over two electrified lines near Ridgemont, Milton Keynes.
The project of works started as a relatively low steelwork repair scheme, with the main scope of works focused on the replacement of a timber decking system suffering from severe degradation as it came to the end of its life cycle. The ongoing access requirements and existing profile of the structure meant a decision was made not to encapsulate the entire bridge but to utilise hydroblasting to remove the paint work, allowing a thorough investigation before a full schedule of works could be agreed.
The steelwork, particularly above the bearers, had severely corroded, along with majority of the deck crossbeams. To reinstate the structural integrity of the bridge, the project scope was increased to replace or refurbish more than 50% of the original structure.
The largest of the bridge repairs took place internally and externally on the web and stiffeners situated above the pier bearing locations. The extent and location of the area for repair led Roberts & Sale to undertake a new and innovative installation methodology. Collaborating with the client − Story Contracting Ltd − the decision was made to weld the new web top and packing plates, as well as the stiffeners, directly into position.
The severity of the corrosion and scale of the affected areas meant this approach delivered a high-quality repair on site to the exact dimensions and prevented a loss of connection where there was significant section loss. To achieve this in line with the programme deliverable dates, an innovative approach was designed with the scaffold allowing pedestrian access with a vehicle either side.
Flash blasting was completed in all areas of the repairs via localised encapsulating to ensure a faying surface before further refurbishment works continued. The repairs were sequenced to meet the revised programme of works, while allowing for the simultaneous installation of a modular GRP structural deck solution. Dura Slab 100, supplied by Dura Composites, was suitable to take the 7.5 tonne loading requirement and made an ideal solution with a grit-blasted surface finish, painted to an M24 paint specification.
Roberts & Sale worked closely with the client throughout the project to ensure the new designs for Checkleys Bridge were both feasible and buildable. The repairs met the revised programme and ensured minimal disruption to the affected landowner. The challenges of access and multiple disciplines meant the project had to be approached with an honest and clear programme to achieve key project milestones. At times, taking an innovative approach meant embracing new ideas and installation methodology.
Checkleys Bridge is one of many practical and innovative project solutions delivered by Roberts & Sale Construction (UK) Ltd within both the rail and civil sectors. Its approach to delivering the best standard of workmanship within agreed timescales makes it a highly respected contractor within the railway industry.