Why do railroads buckle?

Answer 1

Rail buckling or what is commonly known as "sun kinks" occur on railroads during peaks of extreme heat. In North America this problem occurs during the summer months in the desert areas of the Southwest. What happens is that the rail expands lengthwise more than normal. During construction there is a small gap between joining rails which does allow for some expansion, but when there are record high temperatures this gap may not be enough. The rails continue to expand lengthwise until they can expand no more. Then the rails begin to kink and straight sections of track are no longer straight anymore. If a sun kink is not detected and a train travels over this section it can cause a derailment. Good track maintenance sometimes can prevent this from happening, and patrolling the tracks ahead of trains is sometimes done as a precaution on hot days to prevent derailments.