Wadhurst Cutting - London End
Stabilising the 170-year-old Wadhurst Tunnel cutting to prevent landslips
BAM Ritchies (for Network Rail)
Finalist in 2022, Ground Engineering Awards - UK Geotechnical Project with a value of over £3m, WINNER OF THE EDITOR AWARD
The Wadhurst Cutting, situated along the Tonbridge to Hastings railway line in East Sussex, has served as a vital transportation route connecting Hastings and London for over a hundred years. The cutting height is between eight and 18 meters, and its length is roughly 300 meters.
After continuous failures of the over-steepened cutting caused by the Wadhurst Clay Formation (clay/mudstone) and the Ashdown formation (sandstone & siltstone), our client, BAM Ritchies was engaged to remediate the cutting in a two-phased project, the Country end and London end. Over seven days in October 2021, we worked with BAM Ritchies to stabilise the 170-year-old Wadhurst Cutting, which had suffered from several recent landslips. Over 5,400 soil nails were installed, with 15,000 m2 of vegetation removed to protect the railway from the effects of rainfall and extreme weather.
BAM Ritchies appointed Ayesa to the role of designing and developing an approved solution for the cutting and determining whether and to what extent value engineering was feasible for the project. The value engineering work carried out by BLA significantly reduced both the cost and programme of the project, and the close relationship between the project team (BAM Ritchies/Nuttall/ Ayesa) allowed for any construction issues to be mitigated quickly and efficiently.
Sustainability was a major driving force behind this project, as seen by Ayesa and BAM Ritchies' efforts to ensure the use of woven coir matting rather than an erosion mat composed of plastic to prevent the release of microplastic into the environment.
The ecological challenges of the site included the management of a resident badger sett which needed a licence and permission to close the sett, in advance of our works. Also on site were Dormice, which required the creation of a dead hedge mouse highway to avoid the works and also to secure a licence to plant Dormice-friendly plants upon completion of the works.
Benefits and Innovation
Given the proximity to the track, part of the project was finished in a seven-day incident-free period using a sustainable delivery method that was digitally rehearsed to provide resilience to the earthwork’s infrastructure at the Kent and Sussex Railway.
The proposed BL alterations to the design offered a 46 percent reduction in the liner meters of soil nails and rock bolts installed and reduced the programme by 20 weeks, reducing overall cost by around £1.5 million with fewer materials input.
- Reduced risk of landslips on the line;
- Less overall disruption to passengers;
- Safer, reliable journeys;
- Reduced environmental risks;
- Ecologically sympathetic.
"A fantastic effort by all parties involved included supply chain partners which show the power of collaboration by creating one team focused on the project’s success." - Chris Gough, Project Director - Guildford Office