One of the sensory experiences of riding a train is the sound of ingenuity. As steel railroad tracks heat up, they grow: 1,800 feet of rail expands by more than an inch for every 10 degrees Fahrenheit of temperature increase. So rails used to be laid down in sections — each between 30 and 60 feet long — with small gaps.

“The very specific railway noise that you hear — chuchat … chuchat … chuchat … chuchat … chuchat — is because there is a gap between the rails, and this gap is meant for such expansion,” said Dev Niyogi, who studies urban climate extremes at the University of Texas at Austin. 

But in a severe heat wave, the rail can swell until the underlying ties can no longer contain it. Then the rail gets visibly wavy, morphing into what’s known as a sun kink. That’s a serious hazard for trains, which can derail on misaligned tracks. In extreme cases, tracks […]