Travelling during hot weather and staying hydrated

Hot Weather

Travelling in high temperatures and how it impacts the railway

Extreme temperatures in the summer months can pose a challenge for the railway, making travel uncomfortable and disrupting our train services. It can pose a risk to our customers, colleagues and the infrastructure of the railway, including track, sets of points, signals and electrical equipment.

Together with our colleagues at Network Rail we now carry out more preparation for hot weather than ever before to provide the most reliable train service possible across the South Western Railway network.

In cases of extreme heat we may have to change our timetable in order to provide a service that our customers can rely on. Revised timetables will minimise, as far as possible, the potential for delays and short-notice cancellations. 

Advice for travelling in hot weather

Travelling in extreme heat can be uncomfortable, especially during peak hours.

Keeping hydrated is one of the best ways to stay comfortable. London Waterloo has a free bottle refill point with fresh water on the balcony opposite platforms 1 and 2 – ideal for topping up on the journey home.

If you are pregnant, staying hydrated is even more important. Drink 10-12 glasses of water a day – more if there is a heatwave. Stick to the shade and avoid standing on open platforms in the middle of the day if you can.

Most of our trains have air conditioning but it is always worthwhile carrying a fan. Remember you can also apply for our Mums to be Scheme and request priority seating if you need to sit down.

If you are feeling ill then please leave the train at the next station. We can arrange help for you through a help point or with colleagues on platforms. Please do not use the emergency alarms on board if you are feeling unwell – they can stop the train and prevent us getting help to you.

Extreme weather timetables

In June and July 2022 Great Britain experienced extremely hot weather with air temperatures in the south west approaching 40 degrees. 

Extreme heat like this has a significant impact on the railway. There is a risk that rails can buckle, leading to speed restrictions that slow our trains down and make it difficult to run services on time. Signals (the railway’s traffic lights) can also be at risk, causing even more disruption.

As of 2023, when we anticipate that extreme weather has the potential to cause significant disruption, and when speed restrictions are set to be imposed, we will consider operating a revised or reduced timetable. While fewer trains may run, they will be less likely to be delayed or cancelled, giving customers more confidence when planning their journeys.

Any significant timetable changes will be advertised on our Plan My Journey page.

Heat-proofing at key locations

Knowing the risk to rails and signals, engineers have identified key locations on our network to carry out pro-active heat proofing.

Rails in these locations have been stressed to withstand higher temperatures, while layers of reflective, heat-resistant film have been installed on signalling infrastructure to ensure they stay powered.

New heat-monitoring technology has been installed on engineering trains, allowing engineers to detect and quickly repair heat-related infrastructure faults. 
Extreme temperatures can cause disturbances in track levels and so tampers – specialist engineering trains that compact ballast below tracks to keep them level – have been strategically deployed, allowing them to get to where they are needed faster.

Preparing for Soil Moisture Deficit

The summer of 2022, which was the south of England’s driest July since 1936 and included two heat waves, caused serious disruption on our network.
This was particularly felt on our West of England Line between Salisbury and Gillingham, where an amended timetable was put in place between September and November.

This temporary timetable was introduced due to Soil Moisture Deficit (SMD), a problem that sees clay embankments shrink due to a lack of moisture, disturbing the track above. Those track level problems meant our trains could only run at around half their normal speeds, meaning it was not possible to provide services to the normal timetable. 

That summer’s levels of SMD were the worst we had seen on our network for a decade. Following that period of disruption, we have worked with Network Rail to improve the way in which we monitor SMD and have a better understanding of the moisture levels of our embankments.

We also have a better understanding of the trigger points and when interventions, such as speed restrictions and timetable changes, are required. While there is no immediate fix for this complex problem, we can now provide customers with more warning of upcoming changes to train times, thanks to improved monitoring.  

To learn more about how hot weather affects the railway, visit Network Rail’s website.