Yes, fire is used to keep Chicago trains running in the cold

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If you see fire along Metra tracks on this frigid Wednesday, don’t panic. The Chicago area’s commuter rail service is fighting the cold with fire to keep switches working, and help with track repairs.

Winter weather can cause snow and ice to clog switches, which control which rail trains run on. Clogged switches can bring trains to a halt until the blockage is cleared.

To combat the problem, Metra uses a gas-fed system that runs adjacent to the rail, generating heat in areas where switches are supposed to make contact. This system is used in normal winter weather, not just in the extreme cold seen Wednesday, explained spokesman Michael Gillis. The system is turned on when the temperature is between 40 and 32 and stays on when it’s below 32.

Extreme cold weather can cause steel to contract, causing breaks, said Metra spokeswoman Meg Thomas-Reile. While Metra uses continuously welded rail on most of the system, there are some locations near switches and some crossings where the rail is bolted together. Those areas are the most vulnerable to separating in frigid temperatures, although breaks can happen anywhere along the line.

Stacey Wescott/Chicago Tribune

Fire warms Metra rails as trains go in and out of the Western Avenue Station in subzero temperatures on Jan. 29, 2019, in Chicago.

Fire warms Metra rails as trains go in and out of the Western Avenue Station in subzero temperatures on Jan. 29, 2019, in Chicago. (Stacey Wescott/Chicago Tribune)

To repair the breaks, Metra heats the rail, usually with a rope soaked in kerosene that is laid along the base of the rail and lit on fire, Thomas-Reile said. The fire heats up the rail and once it expands, workers pull the rails back together and rebolt them or weld them.

Depending on the damage, workers also may need to cut and insert a short section of rail and weld it in place to bring the rails back together, Thomas-Reile said.

Broken tracks, switch problems and other mechanical issues have caused extensive delays on the Metra system Wednesday, especially on the Union Pacific Northwest from Harvard and McHenry, where delays can be more than an hour. Metra Electric District service has been suspended because of wire problems.

Metra service overall is running on a modified schedule Wednesday and Thursday because of the cold. For updates on the agency’s service, check Metra’s website.

mwisniewski@chicagotribune.com Twitter @marywizchicago