UK Railway Landslip: Early Warnings and Wider Movements

Rail embankment instability was identifiable years before the landslip, with movements extending wider than the limited failure location.

February 26, 2026

A landslip on 23 January caused one of the tracks on a busy railway line in Surrey, UK, to be left hanging in mid-air. The slip occurred after a period of persistent rain, when the soil gave way along a nine‑metre section of embankment, sliding out from beneath the tracks.

The incident near Ockley led to the complete closure of the double‑track line between Horsham and Dorking for three weeks. Substantial remediation works were carried out, to rebuild the failed embankment.

ValueSpace assessed the railway section to determine whether there were prior indicators of developing structural instability concerning the embankment, signalling increased susceptibility to landslips.

Above: A view of the rail landslip on the line between Horsham and Dorking. Below: The landslip area in relation to the wider prior movement cluster on the embankment, as identified by ValueSpace’s assessment.

Satellite analytics from May 2023 up to the incident in January 2026 identified significant and persistent movements at the site of the embankment failure. Furthermore, the section of embankment exhibiting identical precursors extends beyond the landslip location.

ValueSpace’s assessment shows:

  • Continuous subsidence of the railway and the embankment at the landslip location throughout the analysis period.

  • The identified prior movement cluster covers the landslip location and extends ca. 60–70 metres further south along the railway and embankment.

  • A detailed breakdown of the movement data shows that subsidence affecting the rail embankment accelerated ahead of the failure.

The movement cluster identified by ValueSpace exhibited subsidence with a velocity of up to 20 mm/y from May 2023 to September 2024, stabilising at 11 mm/y until April 2025. From April 2025 the subsidence accelerated, reaching up to 28 mm/y.

Regular satellite monitoring of the railway section could have highlighted the signs of increasing embankment instability at the landslip location years before the incident. The assessment further indicates that the preconditions for the development of significant events affecting the embankment may not be limited to the now‑repaired failure location.

Satellite‑based infrastructure monitoring and assessments help identify early signs of instability and to plan effective interventions both before and after failure incidents.

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