Geotechnical assessment and remediation of slope failures along the Tyne Valley (Northumberland) from 2016 to inform future UK rail earthwork resilience

Between January and April 2016, three cutting slope failures occurred at Farnley Haugh, Prudhoe and Wylam Scar, along the Newcastle-Carlisle railway line in the Tyne Valley, Northumberland, UK. The valley's superficial geology comprises a complex sequence of Devensian tills, granular glaciofluvial deposits and laminated high-plasticity clays, causing spatial variability in slope stability due to differing soil shear strengths and groundwater conditions. The Farnley Haugh failure was the most significant, severely damaging the railway and causing a line blockage. All three failures occurred during periods of heavy rainfall. Geomorphological and geotechnical assessments showed the original cutting slopes were over-steep with thick granular glaciofluvial deposits exposed on their faces. Forensic slope stability analyses using data from site works, laboratory testing and historical records indicated that before failure, the slopes possessed only marginal stability and low resilience to extreme weather linked to climate change. Existing drainage and vegetation root systems provided insufficient protection. This study demonstrates that substantial sections of Northumberland's aging rail infrastructure remain vulnerable. As climate change intensifies, earthwork deterioration rates will continue to increase. Long-term investment is therefore essential to monitor, maintain and ensure the future safety and resilience of British rail infrastructure.