Rainfall-triggered rockfall on Highway 18 in San Bernardino County has blocked lanes and damaged barriers along a steep cut slope, following weeks of intense winter storms that saturated highly fractured granitic and metamorphic rock. Caltrans geotechnical crews report multiple failures from tension cracks and oversteepened slopes above the roadway, with debris reaching the carriageway and impacting existing rockfall fences. Engineers are now assessing options including expanded rock bolting, additional draped mesh, improved surface and subsurface drainage, and revised slope scaling protocols ahead of further atmospheric river events.

Lineside monitoring systems on parts of Britain’s rail network may fail to detect embankment or cutting slope movements during extreme rainfall, the Rail Accident Investigation Branch has warned following the 3 November passenger train derailment near Shap, Cumbria. The warning concerns remote condition monitoring equipment installed to trigger alerts for ground instability, which did not prevent the derailment. Geotechnical and asset engineers are being urged to review sensor siting, trigger thresholds and system performance in severe weather, particularly on high-risk slopes.

Railway managers have been warned by the Rail Accident Investigation Branch that Network Rail’s lineside slope monitoring systems may fail to give usable alerts during rapid failures, after an Avanti West Coast train derailed at around 83 mph near Shap Summit on 3 November 2025 when it struck landslip debris. Remote sensors on steel spikes at 2 m spacing recorded sub‑10 mm movements—below the 10–30 mm “green” alert threshold—before being rapidly buried, losing wireless signal and generating no alarm to control. The landslip followed heavy, sustained rainfall that overwhelmed a cutting‑slope drainage channel, and RAIB has urged duty holders to urgently review and, where needed, mitigate these monitoring limitations.