South Western Railway (SWR) is expected to become the latest rail company to announce timetable changes and reduced speeds. This action is in response to the effects of hot and dry weather, which has led to persistent drought conditions affecting the ground supporting railway embankments across southern England.
Operators in the east of England have already stated they will take similar steps. Network Rail previously announced that late-night speed restrictions and altered timetables would begin from 3 August, continuing until ground conditions recover. Routes affected include those run by Great Northern in Cambridgeshire and Norfolk, Greater Anglia and c2c in Essex, and the eastern end of the Elizabeth line.
The measures address “soil moisture deficit” caused by unusually low spring rainfall followed by hot, dry summer weather. Many sections of Britain’s railway network are built on clay soil embankments, which shrink when moisture is reduced during long periods of drought. This shrinkage can disturb track foundations, causing sleepers to drop or move, necessitating reduced train speeds for safety.
SWR's West of England line, connecting London to destinations such as Exeter St David’s, Salisbury, and Yeovil, is particularly vulnerable. Speed restrictions on the predominantly single-track line between Salisbury and Exeter could lead to cumulative delays and knock-on impacts across the network.