Rail Bridge Repaired at Express Speed

Twistfix-registered contractors Newman Building Solutions recently completed a masonry arch bridge-reinforcement project in North London. The bridge, which gives high-speed trains access to the centre of the city, had cracked and was bowed, causing concern for its long-term safety.

A detailed examination and inspection of the bridge was first carried out in order to accurately diagnose the problem. The results of this survey showed that the spandrel of the bridge had suffered from extensive de-lamination which had caused brickwork to become separated from the masonry arch. Additionally some horizontal shear movement had occurred to the 4 course thick brick barrel. These defects had severely weakened the structure and the soffit, which distributes loads across the arch, had shown definite signs of racking which had been originally caused by vibration from passing trains. Water had penetrated deeply into the bridge, causing the pointing to become defective. In addition to this array of problems, the brick pier of the bridge had also suffered minor cracking.

As the bridge was so frequently used, time was a major concern during the project. To allow work to proceed more quickly, a van-mounted cherry picker was used in place of traditional scaffolding for the complex structural repair scheme.

To repair the severely damaged arch, the structural engineers specified that Newman Building Solutions used the highly engineered Twistfix helical reinforcement bars to create a grid pattern across the masonry arch; each bar was grouted into place to evenly distribute the structural loads.

One metre long brick pinning ties were then installed with grout stitch the brick arch through the soffit, pinning it and preventing it from suffering further de-lamination. Another 4,000 Long Pin Wall Ties were dry-fixed in 4 shifts to rapidly re-connect the exposed course of of the arch to the course adjacent to the extrados, thus eliminating the horizontal shear movement and increasing the effective thickness of the barrel for added strength. Both the bridge and the road passing underneath remained open throughout the essential work and the bridge is now restored to its full structural integrity.

Our comprehensive range of structural repair systems is trusted by professionals to provide results of the highest standard. We would like to congratulate Newman Building Solutions on their successful completion of this project.

For more information on Twistfix masonry reinforcement products, please call our team on 0845 123 6006 or email us at sales@twistfix.co.uk.