Efficient and sustainable solution to strengthen the M25 network – carbon fibre rods installed for the first time in the UK
We successfully reopened the Swanley Interchange for the travelling public two weeks ahead of programme, following 12 weeks of reconstruction and strengthening works on the east bridge.
After several years of meticulous planning and trials, the M25 team mobilised at Swanley in July 2023 to strengthen and replace the original steel plates that sit beneath the road which were deteriorating. Thinking differently to accommodate the road and substructure conditions, the team devised a bespoke innovative engineering solution which involved sequentially removing the existing steel plates and replacing them with carbon fibre-reinforced polymer rods (CFRP). 182 CFPR rods were installed in total, a first on the UK and M25 network! The fibres are lighter weight, less likely to crack and able to withstand the harshest environmental conditions in comparison to traditional steel plates. It also remains resistant to corrosion and decay, ensuring that any structural components protected with carbon fibre will maintain their operational efficiency over time.
The team removed the original surfacing, waterproofing layers and grout layers. Ahead of installing the rods the team needed to prepare the existing deck slabs and needed to cut groves for the insertion of the rods. To help save time and ensure the work was completed to programme the team developed a bespoke bracket that secured to a track saw. This bracket featured a retractable extended arm, enabling the cutting of multiple grooves with a single anchoring setup, saving approximately 4 hours per shift that would be needed to move the bracket after each groove is completed.
Furthermore, to delight our customers and guarantee the road works met exceptional standards for future-proofing the network, the team went above and beyond to carry out repair works. After removing the initial rows of existing strengthening plates in the early stages of the program they discovered that more repairs than initially anticipated were needed due to delaminated concrete. Swiftly responding, the team mobilised additional resources and implemented an extra weekend shift to accomplish all the additional repairs, successfully completing the entire process within just two days!
All works were carried out under traffic management and to minimise disruption to road users each lane was sequentially closed to allow traffic to continue.
Following the success of the installation of the rods for the first time in the UK, our project team are now working with our customer, Connect Plus to implement this solution as a permanent design for future projects.
Well done to the team for thinking differently, implementing several efficiencies which allowed the works to be completed ahead of schedule.