Imagine that you’re getting bundled up for your morning commute to work. It’s a cold winter day with below zero temps. (For some of you, you don’t even have to imagine. This has been your life this week.)

Now, imagine that your commute involves taking a commuter train into Chicago. Imagine sitting inside the train and looking out the window. You see the world passing by, but then you see something alarming. The train tracks are on fire. Flames are literally coming up from the tracks, and your train is headed right towards them at full speed.

If you live in Chicago, you don’t have to imagine this scenario either. You probably saw it for yourself. This is real life, and the tracks were lit on fire on purpose.

We’re not talking about a case of arson. Setting the train tracks on fire is actually what they do in Chicago when the temperatures are polar vortex sub-zero cold.

Technically, the train tracks aren’t actually being set on fire. There’s a warming system that runs along the side of the tracks, and the result is that you often see flames coming up from the tracks.

You see, when it gets this cold, the train tracks can pull apart from each other. Warming up the tracks helps them expand so that the trains can run as usual until workers can fix the tracks. Another reason that the flames are actually a good thing is that they can melt any snow and ice that could otherwise clog up railroad switch points.

Yes, trains run right over the tracks even when they’re on fire. According to Chicago’s commuter rail system, Metra, this is perfectly safe since the trains run on diesel fuel which “combusts only with pressure and heat, not open flames.” Even still, railroad workers are on site and monitor the tracks when they’re ablaze.

Watch the video below for more details and to see trains run right over the fiery tracks.

What’s the weather like where you live? Have you ever seen train tracks on fire before?