© MetraTo combat the severe winter weather that hits Chicago, the Metra rail service uses controlled burns to melt disruptive ice from train switches.
- Chicago's suburban Metra train uses fire to clear ice from its busiest switch.
- The heater works better than passive hot air blowers on the large area of switches.
- Switches must make contact for trains to continue through them at speed.
Metra, the commuter train service that covers Chicagoland, is fighting ice with fire.
To combat the severe cold and winter weather that hits Chicago's metropolitan area this time of year, Metra uses controlled burns to melt disruptive ice from train switches. See the process in action here:
? Join Pop Mech Pro and get exclusive answers to your burning science questions>>>P, starting NOW.
Fire solves a big problem for the commuter trains. Ice accumulates and freezes even more quickly on metal tracks because of the way metal holds cold temperatures. When that ice is on the Metra train switch-the place where trains can change routes by switching tracks-it disrupts the flow of electricity that helps train engineers keep driving at speed. The trains must slow to a halt and wait for the switch instead of passing through quickly.
Metra's open flames look dramatic, but the technology is more like your gas stove than anything else: a very safe, controlled fire fueled by a gas line that runs adjacent to the rail. Metra says this is useful because one particular switch, A-2, can't be served by their usual solution of a hot air blower.
© Metrametra switch heaters
A-2 is Chicagoland's busiest intersection of Metra tracks. The Chicago Tribune explained in 2019:
"More than 350 trains pass through the stretch daily. Overseeing all of the train traffic is a switching apparatus built in the 1930s. A Metra employee works a row of levers on the machine like an old-time telephone operator, controlling 31 air-powered switches on the tracks outside. The switching system still works most of the time, but it was built for a different era, when rail service was dominated by freight and long-distance passenger trains."
Mechanical workings from the 1930s can still operate fine if they're well maintained, but Metra wants to upgrade to reduce the bottleneck caused by increased commuter trains. The Tribune explains that Metra must custom fabricate any parts needed for its 1930s workings. And it's easy to see how this critical bottleneck must be much worse under icy conditions.
? Stuff We Love: Our Favorite Hobby Model Trains
Why don't the traditional air blowers work at the A-2 switching facility? Because there are so many switches across such a large area that the hot air won't make it the whole way. Think about how long it takes to thaw a whole turkey for Thanksgiving compared with a frozen chicken tender you just put directly in the oven. The density means heat takes much longer to penetrate.
Trains around the (wintry) world use switch heaters, which are manufactured by several different companies and critical to clearing the contact points that allow switches to be operated. Chicago's Metra is notable both for the large size of the A-2 switching facility and for the open-flame switch heater that, so far, is the best way to keep all the tracks clear.
Metra says a few bits of railroad equipment are damaged each year by the open flames-but it's a small price to pay to keep the trains running smoothly.
?? Now Watch This: