RAIL travellers are facing disruption due to the baking temperatures.

Network Rail engineers are monitoring tracks on the London to South Wales line to make sure the heat does not make them dangerous.

They have announced the speed limit will be reduced to 60mph, less than half the normal speed, westbound between Wootton Bassett and Patchway, near Bristol Parkway, and the line from London to Wootton Bassett is subjected to a reduced limit of 90mph in both directions. The eastbound line from Patchway to Wootton Bassett is unaffected by the heat.

First Great Western have axed half the services to and from South Wales, disrupting arrangements for thousands of passengers during the busy holiday season. Trains leaving at 55 minutes past the hour from Cardiff Central and 30 minutes past the hour from London have been cancelled.

First Great Western spokesman Tim Bowcock said: "Our policy is to adhere to the speed limits, and to keep our customers informed, and hope they understand why we need to put the measures in place.

"This timetable is a temporary measure and will be reviewed regularly."

Network Rail spokesman Callum Collins said it was keeping the situation under review, but was largely powerless to act.

"There is little we can do. We can't go dousing the tracks with water, so we monitor rail heat regularly, and let the tracks cool naturally."

A variety of factors are taken into account in determining speed limits, including air temperature, how much sun hits the tracks, the line's normal speed limit, whether the line is used mainly by passenger or freight services, and whether the track has recently been repaired.