Train disruption warning in southern England as clay embankments crumble

Train travel across southern England risks being disrupted after a number of Victorian-era clay embankments that support railway tracks began crumbling following months of dry weather.

Track owner Network Rail has warned that prolonged dryness can cause clay to crack “and can sometimes make the track sitting on top of it uneven too”.

This could happen anywhere the railway was built on clay, it said. “Areas where the soil has a high clay content include parts of London and the south-east, where London and Wealden clay is prevalent,” it added.

Two rail operators so far have taken emergency measures because of clay erosion. Greater Anglia this week cut late night services to allow repair works to shore up the track in Essex.

Meanwhile, South Western Railway has halved the frequency of trains running between Yeovil and Exeter. The change was necessary because of a speed restriction imposed in an area where a clay embankment had shrunk.

Network Rail said: “It typically takes several months of wet weather to bring the moisture content back up so we can’t just sit and wait for rain”.

It added: “We can’t really repair the bumpy track until the soil has stopped moving, so speed restrictions are the best stop gap until we can”.

The problems are among a series facing railways in the UK and other countries as climate change makes climactic events more extreme. Downpours in rain storms have also become more torrential in a warmer climate, making it harder for ageing trackside drainage systems to cope.

Rupert Brennan-Brown, a veteran railway industry insider, said “growing climactic extremes” were placing “significant pressures” on railway infrastructure.

“This will inevitably impact on users of the railway, both passenger and freight,” Brennan-Brown said.

The two areas so far affected are among many across southern England where Victorian engineers laid rail tracks on embankments built from the area’s clay soil. Clay tends to absorb water readily but also shrinks sharply during long, dry periods.

The Met Office has said this spring in England was the second-driest since records began in 1836.

Ground in many places remains unusually dry and there are concerns that track could shift dangerously as a result of this “soil moisture deficiency”.

It stressed, however, that “currently” the only two places where customer journeys were being affected were near Shenfield, Essex, and Crewkerne, Somerset.

Services on the South West Main Line in Somerset are particularly badly affected because the line is single track.

Network Rail has said trains have to slow from their normal 85mph through the affected area to 40mph, to avoid derailments and minimise damage to the affected track.

The speed restriction meant trains travelling in opposite directions would not have reached passing points at the correct times. South Western has cut the service to one train every two hours to maintain a reliable service.

In Essex, meanwhile, engineers are dealing with the problems by putting extra ballast under the track to shore it up. The work would affect some late-night trains, from August 11 until further notice, on Monday to Thursday evenings, Great Anglia said.

A third operator, Great Northern, had to cancel some late-night trains between Ely and King’s Lynn last week to allow repairs to uneven track over very dry peat soil, although the temporary measure has now been lifted.

Network Rail said it would monitor conditions carefully. “The key thing is that our engineers monitor track quality and soil moisture to make sure trains are able to continue running safely and we take the right action when we need to,” it said.