Tens of millions of people across the US are currently under a heat advisory. And the extreme heat isn't just affecting people. You may have seen videos online of the heat causing asphalt roads to buckle. It is impacting rail travel too. Amtrak has been running some trains more slowly, as have the public transit systems of Washington and Philadelphia.Mikhail Chester, an engineering professor at Arizona State University, talks through the intersection of extreme heat and transportation.And NPR's Julia Simon shares advice on how people can keep themselves cool.For sponsor-free episodes of Consider This, sign up for Consider This+ via Apple Podcasts or at plus.npr.org. Email us at [email protected] more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy