A Bridge Too Far? Not for Excalibur!
Network Rail’s Swanley Works Delivery team were tasked with trialling new chair bolts at the Charing Cross location. This site was particularly noted for failures brought on by the timbers frequently expanding and contracting over and above standard tolerances.
Commencing in April 2022 Excalibur were asked to trial approx. 500 screws in 18 x 10m+ timbers and 3 x 2.6m timbers. The timbers were drilled out using 19mm drill bits using sleeper drills and Excalibur Sleeper bolts driven in with 30mm hex head attachments using Bance petrol powered impact drivers. No lubricants were used to aid the installation, although typically sites using hardwood sleepers and traditional rail screw spikes have had to lubricate the screws to stop them overheating from the force of the screw being driven in which causes heavy friction and slows down the installation and can cause splits in the timbers. In June 2023 Swanley Works Delivery reported on the trial site, with the following results, despite evidence of water ingress and hot weather effects on the timbers:
- No signs of star cracking around bolt holes
- No signs of base plate lifting
- Excalibur Screwbolts are firmly seated
- Installation Time Saved
- Reduced HAV’s
- Reduced Manual Labour
In addition the report, by Charlie Clark, noted; Using 19mm drill bits as per standard for timbers, the Excalibur Sleeper Bolts found the drilled holes very easily with no issues. Rather than applying outward pressure at the top of the hole to hold the baseplate like standard AS screws the Excalibur Sleeper Bolts cut their own thread into the timber. As a result, the Excalibur bolts work with the impact wrench to drive bolts into the hole, making installation quicker on each bolt and results in time savings that only increase the larger the volume of job scope.
Unlike traditional rail screw spikes there was no lubricant required to aid the Excalibur bolts in, being driven home into the drilled holes, again, reductions in manual handling, HAV’s, site tidiness and time saved were recorded.
The standard hex head socket used aids torque applied to the bolt head which again helps the speed at which the bolt is driven in to the timber, we think the Excalibur Sleeper Bolts would also aid us to transition to battery powered tools much quicker given how easily they can be inserted which would have an even greater impact on workforce welfare, HAV’s, COSHH and environmental impact.
