Persistent drought conditions are expected to disrupt rail services across southern England, with operators like South Western Railway likely to announce reduced speeds and timetable changes. The lack of rainfall causes clay soil supporting railway embankments to shrink, disturbing track geometry and necessitating slower train speeds for safety.
The ongoing heatwave and drought highlight the vulnerability of critical infrastructure like the UK's rail network to climate change impacts, potentially leading to recurring disruptions and increased operational costs for rail operators.
Persistent drought conditions exacerbated by the climate crisis are poised to cause further disruptions to train services across southern England. The lack of rainfall is impacting the ground supporting railway embankments, leading operators to consider reduced speeds and altered timetables.
South Western Railway is anticipated to be the next major operator to announce such changes, following similar steps taken by operators in eastern England. Network Rail stated last week that late-night speed restrictions and modified timetables would be necessary from August 3 until ground conditions recover. Affected routes include those operated by Great Northern in Cambridgeshire and Norfolk, Greater Anglia and c2c in Essex, and the eastern section of the Elizabeth line.
The measures are a response to "soil moisture deficit" (SMD) resulting from unusually low rainfall in spring and subsequent hot, dry summer weather. Many sections of the UK's railway network are built on clay soil embankments, which normally retain significant moisture. Prolonged drought causes this soil to shrink, disturbing the ground beneath the tracks and potentially causing sleepers to drop or shift. Even minor alterations in track geometry necessitate trains reducing speed for safety.
South Western Railway's West of England line, connecting London to destinations like Exeter, Salisbury, and Yeovil, is particularly susceptible. Given that the Salisbury to Exeter line is predominantly single-track, speed restrictions can lead to cumulative delays and network-wide knock-on effects.
Last week, Great Northern announced timetable adjustments from August 3 for its services to and from King's Lynn. Greater Anglia will modify some evening services in Essex, and some late c2c services to Shoeburyness will also change. The Elizabeth line will operate a reduced service between Gidea Park and Shenfield from 11 p.m. to midnight on specific dates.
Network Rail engineers work to mitigate the effects of dried-out soil by using machines called tampers to lift the track, insert stone ballast underneath, and create a stable foundation. New ballast is also added to raise track levels. Last year, approximately 62 miles (100km) of track in Anglia were treated with tampers. In preparation for summer, thousands of tonnes of ballast have already been laid, with an additional 49,000 tonnes expected to be used by 2026.