A main rail line is expected to introduce timetable changes and reduced speeds due to dry weather. An announcement is anticipated soon, affecting the South Western Railway (SWR) line between London and Exeter.
The problem stems from soil shrinkage on rail embankments, which causes the tracks above to buckle. This issue, known as Soil Moisture Deficit (SMD), is currently running at a higher level than in 2025, according to SWR data. The same problem led to reduced services on the line from August to November 2025, changing from hourly to one train every two hours.
SWR train driver Peter Cook noted the visible and palpable movement of rails from his cab, stating it is more exaggerated at greater speeds. Anne Browne from SWR and Network Rail indicated that SMD problems are becoming more regular, occurring almost every year and currently slightly worse than last year.
The West of England line, which connects London with parts of Devon, Dorset, Hampshire, Somerset and Wiltshire, is particularly vulnerable to SMD. This line includes single-track sections with passing loops, meaning delays can have a knock-on effect on other services. SWR stated it can take weeks or months for soil moisture levels to return to normal.