When we had the extreme heat at the end of July, I remember some disruption due to buckling rails and speed restrictions. We are currently having the hottest late August bank holiday weekend on record with temperatues reaching over 30C and still rising, yet I can find nothing about buckling rails this time. Why is it only some periods of hot weather cause this problem? I appreciate the end of July heat was a bit worse than this but I thought the problem occurred whenever air temperatures approach 30C.