Trains from Corby, Kettering and Wellingborough are likely to be delayed or cancelled with longer journey times amid warnings of a record-breaking heatwave.
Speed restrictions are to be imposed across wide parts of the rail network with the speed limit on the Midland Main Line south of Leicester being reduced from 125mph to 60mph.
Rail track temperatures in direct sunlight can often be up to 20 degrees higher than the air temperature - meaning steel rails could top 50C in the sun tomorrow (Thursday) when the air temperature is forecast to reach the mid-30s in Kettering. Because rails are made from steel, they expand when they get hotter and can sometimes curve and buckle.
Rob McIntosh, Managing Director of Network Rail Eastern, said: “Passenger safety will always be our number one priority. And with forecasts of unprecedented temperatures, we have to take action to keep people safe.
“Reducing speed limits will mean fewer services and busier trains on our main routes into and out of London.
“So I’d like to ask all passengers to think about whether their journey is really necessary and, if it is, to make sure they plan well ahead.
“I’m sorry for the disruption this will cause, but it is essential to maintain the safety of the travelling public.”
Train operating companies are working on revised schedules but there will be significantly reduced services, with longer journey times and the likelihood of overcrowding.
Anyone who has to travel should consult operators for the latest travel information, allow extra time for their journey and carry water with them.
It is hoped services will return to normal on Friday with temperatures forecast to drop.