Network Rail is bracing for significant disruption on the railway network as thunderstorms move across several parts of the UK.
Rail chiefs have warned that tracks could become flooded because months of drought have baked the surrounding ground hard, making it far less able to absorb sudden downpours.
As a result, intense rainfall may quickly run off the dry, compacted soil and spill onto railway lines, raising the risk of delays, cancellations and wider travel disruption.
The alert follows last week’s derailment of a train carrying 150 passengers near Lewes in East Sussex during extreme heat, an incident that left 30 people injured.
The Met Office issued thunderstorm warnings on Thursday for parts of the country in the days ahead and into next week, with some areas of Britain already hit by heavy rain.
For many places, it marks the first meaningful rainfall in weeks after a long spell of soaring temperatures left much of Britain parched.
The unsettled weather comes as almost three quarters of England and the whole of Wales remain in drought following a record-breaking summer of heatwaves, while 10.1 million people are living under hosepipe bans.
July rainfall was dramatically below normal, ranging from just 26 per cent of the usual average in northwest England to only 1 per cent in the southeast.
Two people were seriously injured when a train derailed near Lewes, East Sussex
Investigators are looking into whether the tracks had expanded in the heat and started to warp
Experts have, however, warned the return of rainfall may not be enough to reverse the drought conditions affecting much of the country, with weeks of above average rainfall needed to make significant changes.
Speed restrictions or service suspensions are imposed on train services when floodwater rises above rails.
Network Rail told Our News Outlet they ‘are not predicting major disruption from flooding in the short or longer term this year’, but said they are ‘not complacent’.
The warning comes amid heightened scrutiny of Britain’s railway safety following two derailments in the space of 24 hours last week.
Three people were injured in an incident in Lewes, East Sussex, on August 13, while there were no casualties when a train came off the tracks but remained upright south of Wickford railway station in Essex.
The eight-carriage Southern service came off the tracks between Haywards Heath and Lewes at around 3.54pm on Thursday, with three carriages overturning and passengers forced to scramble out of the wreckage as temperatures climbed above 35C (95F).
Pictures from the scene show passengers standing on top of the overturned carriages, with emergency crews including Sussex Police, British Transport Police, paramedics and East Sussex Fire and Rescue Service rushing to help those inside.
Action taken by Network Rail to mitigate the risks of flooding include deploying inflatable barriers, clearing debris from drainage systems and building water pumping stations at hotspots.
Leading academics warned of disruption from flooding despite attempts to tackle the issue.
William Powrie, professor of geotechnical engineering at the University of Southampton, warned that downpours ‘could cause disruption’ to rail services, and dealing with more intense rainfall ‘has got to be part of our adaptation to climate change’.
He said there is an increasing need to handle large quantities of rainfall in a short period of time, and the engineering profession must ‘come up with ways of doing this that the nation can afford’.
He went on: ‘There are certain places on the network which I think were known to be susceptible to flooding, and some work has been carried out to try to improve drainage on those areas.
‘Hopefully, the number of places where (heavy rainfall) will cause disruption is going to be fewer because of the ongoing adaptation.
‘But it’s just going to really depend on when, where and how intense the rainfall is.
‘It is something that we do need to be prepared for.’
Dr Ioannis Koliousis, associate professor of logistics and supply chain management at Cranfield School of Management, Bedfordshire, warned of the impact of speed restrictions imposed because of soft ground following rainfall.
He said: ‘If the earth below the lines is a little bit soft, then the train speed will have to be lower, and this affects directly the capacity of the system.
‘We wouldn’t have trains arriving at the (timetabled) time.’
John Lawrence, who chairs the railway technical network at the Institution of Engineering and Technology, said measures taken in response to greater flooding risk on the railways include raising trackside electrical equipment.
He explained: ‘That might not help you when the rails are flooded, but it will enable you to get back into operational service much more quickly because the electrical equipment is not being damaged by floodwater.
‘There’s been quite a bit of that going on in the background.
‘We’re doing a lot in terms of monitoring the stability of embankments, and there’s quite a lot of innovation going into drainage as well.’
A spokesperson for Network Rail said: ‘We are not predicting major disruption from flooding in the short or longer term this year. However we are not complacent. Our long-range forecast suggests it will be a warm, wet winter – in line with climate change predictions for Britain – and we are doing all we can to be ready for that.
‘A programme of improving the railway’s resilience is ongoing, with projects such as the recently completed scheme at Chipping Sodbury on the Great Western Main Line, alongside maintaining and checking drainage and working with landowners around the railway to keep our lines safe so people can travel with confidence.’
