There are a number of climate clickbait videos making their way around Twitter today that suggest Chicago has set some of the city’s railroad track on fire to deal with the extreme cold caused by the polar vortex.

For example, CNN:


ABC News:

And NBC News:

But what you’re really seeing in the photos are “switch heaters” and they’re common in Chicago during the winter:

Here’s an explanation via Metra’s website:

Some riders may have seen the open flames licking the rails at the A-2 interlocking. Despite popular belief, the tracks themselves are not on fire. Instead, the flames come from a gas-fed system that runs adjacent to the rail, generating heat on the critical areas where the switches are supposed to make contact. Without that contact, the switches default to “fail-safe” mode, which means any trains that need to pass through the interlocking will have to wait until the switches make contact with the rail and complete an electric circuit. Until then, train movement is halted.

The heaters help keep the switches clear (although sometimes the snow and ice falls too fast or falls from the underside of a passing train and the switches need to be cleared manually with brooms, shovels or picks).

Switch heaters come in a variety of forms. In Metra’s yards, Calrod tubular heaters use electricity to generate radiant heat at switch points. Hot air blowers, which use a combination of gas and electricity, clear other switches in other parts of Metra’s system. However, while the Calrod and hot air blowers are prefabricated systems that Metra purchased, the gas-fed flames at A-2 were customized explicitly for that interlocking.