Why do trains get cancelled when there's a heatwave? Experts reveal why extreme heat makes Britain's public transport network grind to a halt
As temperatures across the UK skyrocket, Britain's public transport network has ground to a halt.
Rail routes across England, Wales and Scotland are experiencing delays and cancellations, leaving thousands of passengers stranded.
Frustrated travellers have flocked to X to discuss the issues.
'That didn't take long… "Severe weather" has delayed nearly all departures from waterloo,' one user wrote, alongside a photo of the crowds.
British astronaut Tim Peake added: 'The mind boggles (as the train crawls its way to London) that we can build a space station that, for nearly 27 years, has coped with temperature fluctuations of +121C in the sun to -157C in the shade, 16 times a day, yet the signalling system on SW Trains flops at +30C.'
And one vented: 'Other countries have hotter weather and I'm sure their train service doesn't collapse like these lot.'
So, why do trains get cancelled when there's a heatwave?
Network Rail has revealed how abnormally high temperatures can cause steel rails across the network to buckle.
With temperatures in parts of the UK set to hit 32°C this weekend, we could see parts of the rails start to buckle
Britain's railway tracks cover more than 20,000 miles and are made from steel.
Most of the network can operate when track temperatures hit up to 46°C, according to Network Rail.
This is the equivalent to an air temperature of around 30°C.
However, with temperatures in parts of the UK set to hit 32°C this weekend, we could see parts of the rails start to buckle.
'When Britain enjoys a summer heatwave, rails in direct sunshine can be as much as 20°C hotter than air temperature,' Network Rail explained.
'Because rails are made from steel, they expand as they get hotter, and can start to curve. This is known as "buckling".'
Network Rail uses remote monitoring systems to keep an eye on its tracks.
When the systems detect that a section of track might be expanding too much and heading towards a buckle, Network Rail introduces local speed restrictions.
British astronaut Tim Peake added: 'The mind boggles (as the train crawls its way to London ) that we can build a space station that, for nearly 27 years, has coped with temperature fluctuations of +121C in the sun to -157C in the shade, 16 times a day, yet the signalling system on SW Trains flops at +30C'
Overhead wires can also overheat
Another issue for railway networks amid the heatwave is the risk of overhead wires overheating.
Overhead wires give power to trains by conducting electricity through the pantograph – an apparatus mounted on the roof of the train.
During heatwaves, the overhead wires can expand and sag, causing the train's pantograph to become entangled in the wires and requiring repairs.
'Slower trains cause lower forces on the track – this reduces the chance of buckling,' it explained.
Unfortunately, even with prevention measures in place, rails can buckle.
When this happens, the network is forced to close the line and carry out repairs before trains can run again.
'This can disrupt journeys because we often have to wait until the rail temperature has dropped before we can carry out these essential repairs,' it added.
Another issue for railway networks amid the heatwave is the risk of overhead wires overheating.
Overhead wires give power to trains by conducting electricity through the pantograph – an apparatus mounted on the roof of the train.
During heatwaves, the overhead wires can expand and sag, causing the train's pantograph to become entangled in the wires and requiring repairs.
Thankfully, much of the ageing overhead wires have been replaced with an auto-tensioned system, similar to those used European countries with more regular heatwaves, such as Italy.
'Modern overhead lines, such as those in place on the lines between Norwich, Ipswich, Colchester, Clacton, Harwich, Braintree, Cambridge and London Liverpool Street, and those installed on the Southend Victoria line, do not sag in high temperatures, avoiding the need for precautionary speed restrictions,' Greater Anglia explained.
One of the key ways that networks prevent tracks from overheating is by painting them white.
Dr John Easton, an executive panel member of the IET's Railway Technical Network, explained: 'This can reduce the track temperature by 5°C and reduces signalling failures which lead to significant disruption.
'This technique is also used in countries where high temperatures are more commonplace, such as Italy, where engineers often paint the inside faces of the rails white to reflect the sunlight and lower the risk of buckling.'
Most tracks across the UK are made of long pieces of rail that are stretched and welded together.
'There is much less chance of buckling in very high temperatures because there is reduced compression,' Network Rail added.
'When a track is made up from short rails bolted together, we leave small gaps between each one so that expansion doesn't cause a problem.'
Meanwhile, in some part of Britain's rail network, tracks are laid on reinforced concrete slabs, rather than on sleepers and ballast - a technique often used to prevent buckling in hotter countries.
While this also helps to prevent damage, it costs about four times as much to install as standard ballasted track.
Worryingly, climate change could increase the frequency and severity of extreme heatwaves, and cause even more chaos for railway networks.
'We work closely with many governmental and specialist organisations to prepare our railway for the climate changes projected over the next few years, decades and beyond,' Network Rail said.
WHY DO STORMS AND HOT WEATHER CAUSE DISRUPTION TO TRAINS AND PLANES?
HOW HOT WEATHER AFFECTS AIRCRAFT
Aircraft components begin to overheat and become damaged in extreme temperatures, with seals softening or melting.
If temperatures exceed 47°C (116°F), planes are grounded as some aircraft manufacturers can't guarantee the necessary engine propulsion.
HOW STORMS AND HOT WEATHER AFFECT FLYING
Aeroplanes fly because the speed of the aircraft causes ambient air to travel over the wings creating lift.
When the flow of air is disrupted, the wing loses, or gains, lift.
Hot air is less dense than cold air, which means aircraft require more engine power to generate the same thrust and lift as they would in cooler climes.
The warmer it gets, the less density there is in the air, which in turn results in less upwind for the wings.
Cumulonimus clouds, which occur during thunderstorms, can also be problematic as they are associated with heavy and sudden down pours of rain.
These clouds are often caused by periods of very hot weather.
Thunderstorms are a challenge for a pilot because there are several dangers like wind shear, turbulence, rain, icing and lightning.
HOW HEAT AFFECTS TRAINS
Thousands of miles of steel tracks cross the UK, much of which is exposed to sunlight.
Tracks in direct sunshine can be as much as 20°C (36°F) hotter than the ambient air temperature according to Network Rail, which manages Britain's railway infrastructure.
Heatwaves can cause points failures and signal disturbances, while in some places the tracks have buckled under the heat.
As temperature rises, the steel rail absorbs heat and expands, causing it to curve, or buckle.
The forces the temperature change provokes pushes and pulls the track out of shape.
Buckled tracks need to be repaired before trains can run again, leading to disruption.
Overhead lines can also expand and sag in extreme heat, bringing a risk of passing trains pulling them down.
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
The Independent
23 minutes ago
- The Independent
Heatwaves declared across England and Wales with higher temperatures to come
Heatwaves have been triggered across England and Wales with even higher temperatures expected over the weekend. But Friday was not the warmest day of the year so far, with highs of 30.8C recorded in both nations, the Met Office confirmed. It comes as thunderstorms are threatening to hit large parts of northern England on Saturday. Temperatures could reach up to 34C in isolated areas of England, but rain, hail and lightning could be on their way, a Met Office spokesperson said. An official heatwave is recorded when areas reach a certain temperature for three consecutive days, with thresholds varying from 25C to 28C in different parts of the UK. 'Many places' in England and 'one or two areas' in Wales, including Cardiff, have now entered a heatwave following Friday's highest temperatures, Becky Mitchell, meteorologist at the Met Office, said. While the national record for this year was not broken, Friday was the hottest day of the year so far for Wales, Northern Ireland and Scotland. A yellow thunderstorm weather warning has been issued covering Nottingham up to above Newcastle, running from 3pm on Saturday until 4am on Sunday. The Met Office warned the most intense storms could produce 'frequent lightning, large hail and gusty winds', along with a chance of flooding. Met Office spokeswoman Nicola Maxey said: 'There are scattered thunderstorms coming through. 'Some of the rain could be quite intense, and frequent lightning, hail, gusty winds and some heavy downpours, which we haven't seen for a while. 'Some of the ground is quite hard at the moment, and when you get heavy rain hitting hard ground, it can cause surface water issues. 'You might find surface water on the roads, drains finding it difficult to cope and a small chance of homes being flooded.' Temperatures are predicted to peak on the western side of the country on Friday, as a 'more changeable, fresher feel' starts to come in. Ms Maxey said: 'Tomorrow, temperatures may continue to go up a little for the east and south-east area of the country, we might see them creep up to 33C, or even an isolated 34C, but we are going to see that change. 'In the west, tomorrow we should start to see more of this cloud come in, and we have a fresher air mass pushing in across the country.' Temperatures reached 32.2C in Kew, west London, on Thursday, amid an amber heat-health alert for all regions in England. The alert, issued by the UK Health Security Agency (UKHSA) for the first time since September 2023, is in force until 9am on Monday. It warns 'significant impacts are likely' across health and social care services because of high temperatures, including a rise in deaths, particularly among those aged 65 and over or people with health conditions. Following the hot weather, the Royal Society for the Prevention of Accidents (RoSPA) has urged the public to take heat and water safety seriously. During 2022's heatwave, temperatures rose past 40C, leading to 320 people being treated in hospital. Steve Cole, policy director at RoSPA, said: 'Heat is no longer just a holiday perk — it's a growing public health risk. 'We're seeing more frequent and intense heatwaves, both in the UK and globally, and the data shows a clear rise in heat-related illness and fatalities. 'Warm weather can also be deceptive when it comes to going for a dip. 'While the air may feel hot, water temperatures often remain dangerously cold, which can lead to cold-water shock, even in summer.'
BBC News
an hour ago
- BBC News
Sussex and Kent water supply 'getting extremely low'
Kent and Sussex residents have been warned to only use water for essential uses after rising temperatures sparked a surge in in Sussex and Kent have been told by Southern Water and South East Water that tanks in the counties have been hit by the rising temperatures in the region in the past East Water say that 661 million litres of water have been used in the past week, while Southern Water warned that Sussex has had less than half of its usual rainfall for the past six months.A spokesperson for the South East Water said: "Our sites are working 24/7 at max capacity, but there is a limit to how much water we can treat and pump at one time." Southern Water added: "If water demand remains high and the hot dry weather continues, we may struggle to treat and supply water fast enough to keep up with demand."The water companies urged customers to stop using jet washers and hosepipes and think about how they can reuse upgraded amber heat health alert was issued on Thursday with temperatures in the South East expected to hit 30⁰C on Saturday 21 heat health alert will remain in place until 09:00 BST on Monday, 23 have begun to be declared across England as higher temperatures are expected to continue across the in the South East have also warned of the risks of cold water shock as Sussex and Kent approach the heatwave threshold.
Daily Mail
an hour ago
- Daily Mail
Northeast braces for record-breaking temperatures
More than 100 million Americans from the Central Plains to the Northeast are bracing for a powerful heat dome that will bring extreme temperatures through next week . A heat dome, a high-pressure system that traps hot air and blocks cooler air, is driving prolonged heat waves across the US. The National Weather Service (NWS) reports that on Friday, temperatures in central states like Colorado , Nebraska , Kansas , Iowa , Missouri and Illinois will climb to the upper 90s to low 100s°F, with heat indices exceeding 105°F due to high humidity. Cities like Omaha, Topeka, and Kansas City face excessive heat warnings, signaling serious health risks for those without adequate cooling or hydration. Minnesota , Wisconsin and Michigan are also sweltering, with highs in the low to mid-90s°F and heat indices nearing 100°F. Minneapolis is among the cities under heat advisories. Over the weekend, the heat dome will shift eastward, intensifying heat in the Ohio Valley, Mid-Atlantic and Northeast. On Saturday, New York City will reach the low 90s°F, with heat indices near 100°F due to humid Atlantic air. By Sunday, Boston and Philadelphia are forecast to hit the mid-90s°F, with heat indices up to 104°F. The NWS urges residents to drink plenty of fluids, stay in air-conditioned spaces, avoid direct sunlight, and check on vulnerable neighbors. Cooling centers are opening in cities like New York and Philadelphia to provide relief. A heat dome occurs when a large area of high pressure in the upper atmosphere acts as a reservoir that traps heat and humidity, said Ricky Castro, a NWS meteorologist in Illinois. AccuWeather Meteorologist Alex Duffus warned: 'From Monday to Wednesday, the Northeast will face dangerous heat, with widespread highs in the 90s and some areas nearing 100°F, spiking energy demands and requiring limited exposure .' The heat dome will peak on Monday, June 23, with the Ohio Valley, Mid-Atlantic, and New England at 'high risk' of extreme heat, potentially straining power grids. Tom Kines, a meteorologist at AccuWeather, said: 'A lot of those folks have been saying, where's summer? Well, buckle up, because it's coming.' With limited days of warmth over much of the northern Plains, Midwest and Northeast so far this year, the surging heat could catch people off guard as it will be accompanied by some of the most intense sunshine of the year along with high humidity levels . With sweltering humidity and relentless daytime heat, many urban areas are expected to see little relief overnight. Temperatures will briefly dip into the 70s before climbing again, making it difficult for those without air conditioning to cool down or recover, according to AccuWeather meteorologist Danielle Ehresman. The intense conditions will likely drive up energy demand and significantly increase the risk of heat-related illness. AccuWeather warns that RealFeel Temperatures could soar 5 to 15 degrees higher than actual readings, topping 100°F in many regions, even where the official highs remain in the 90s. Residents are urged to limit outdoor activity during the midday and afternoon hours when the heat will be at its most oppressive. AccuWeather Senior Meteorologist Chad Merrill said: 'The magnitude and longevity of this heat wave will be a shock to the system.'
