Rail passengers across England and Wales have been urged to only travel if necessary next week, with extreme temperatures forcing blanket speed restrictions across much of the network. Network Rail said the impact on train services would vary by region, but that journeys would take significantly longer. It said there was a high likelihood of cancellations, delays and last-minute alterations to services on Monday and Tuesday. Long-distance train journeys, such as London to York, could take four hours instead of two, with trains forced to travel below 60mph for safety. Vulnerable passengers and those with health conditions should avoid travelling, Network Rail said, while passengers who choose to travel should check if their train is running and ensure they are prepared for the heat with plenty of water to drink. Rail passengers in Scotland should also check their journeys before travelling and take sensible precautions. Jake Kelly, Network Rail’s system operator group director, said: “Rail passengers in England and Wales should only travel if necessary on Monday and Tuesday as there will be delays and cancellations to train services due to the unprecedented heat we’re expecting. “Journeys will take significantly longer and delays are likely as speed restrictions are introduced to keep passengers and railway staff safe. “We’re working closely with MetDesk to monitor forecasts and adapt our plans, and with our train operator colleagues to make sure we can get passengers who need to travel to their destinations safely.” Network Rail’s emergency weather action teams were meeting on Friday to evaluate forecasts showing temperatures could reach 40C, higher than the record of 38.7C in 2019 which caused widespread disruption on the railway. Speed limits are expected to be in place from noon to 8pm on Monday and Tuesday, as the railway infrastructure is susceptible to damage in extreme heat. The temperature of the rails could reach 60C if the air temperature hits 40C, and are more at risk of buckling when trains run faster on them. Overhead lines will also expand and sag in high temperatures, increasing the risk of collision damage and power outages, with points failures also more likely. Network Rail’s incident response teams will also be placed on high alert for lineside fires. Motoring organisations have also said the heatwave is likely to trigger a big increase in breakdowns, with temperatures hot enough to melt tarmac. The RAC is expecting more than 1,000 extra daily breakdowns – about 20% more than normal for the time of year – with the risk of car engine’s overheating or running out of fuel or coolants exacerbated by possible queues to reach beaches or the countryside. RAC breakdown spokesperson Rod Dennis said: “Such a large increase in people needing assistance is bound to put pressure on all breakdown services, so it’s essential drivers have an emergency kit with them to keep as safe as possible while they wait for help – ideally in a safe location in the shade. “Carrying plenty of water, some non-perishable food, emergency medication if needed and a means of blocking out the sun – hats and an umbrella – are all important, as is having a fully charged phone to be able to contact their breakdown provider or the emergency services if necessary.” Gritting trucks may be deployed to spread fine granite dust to help improve vehicle grip on softening road surfaces, Dennis added. Heathrow airport, often one of the hottest locations in the UK, said it did not anticipate any additional operational problems to be caused by the heatwave.