What you're seeing in those videos of Chicago has a simpler explanation.
Look closely, those are double-slip switches and movable-point crossovers at Tower A-2, which is the crossing of the Chicago and North Western, now Union Pacific, line to Elburn for the commuter trains with The Milwaukee Road, now Metra itself, line carrying commuter trains for Elgin, Antioch, and Fox Lake as well as Amtrak for Milwaukee and points northwest. In addition, empty stock workings out of the old North Western and Milwaukee Road coach yards use those tracks to lay up after the rush hour or to stage to the stations for the rush hour.
It's easier to keep the movable components free of snow with strategically-placed heaters, rather than stationing an army of trackmen with brooms and shovels to keep snow and ice from clogging the moving parts and delaying the switching of trains.
Before the installation of the gas-fed heaters, maintainers relied on more interesting (and far more dangerous) systems of melting snow and ice. Workers had to fill what were called “smudge pots" with kerosene, stick them in the spaces between the track ties and light them. This was all done by hand.There's still a maintainer stationed at the crossing as long as the heaters are in operation; perhaps that's one reason Metra operate a reduced evening schedule during the cold snap.
Maintainers light the heaters by hand and can moderate the flow of gas, which makes the flames larger or smaller, depending on need. Additionally, at least one maintainer is stationed at the interlocking every second the heaters are lit in order to monitor the flames. It’s important to note that diesel fuel combusts only with pressure and heat, not open flames. Therefore, operating our locomotives and railcars over the switch heaters is completely safe.Watch:
That's a train headed for the West Line, perhaps all the way to Elburn. Unfortunately, you still can not buy a parlor car seat to DeKalb. Look closely at the power. Metra continue the tradition of named locomotives. Here Village of Winnetka 170 does the honors.
There are switch heaters that rely on forced air, and Union Pacific have them at all the interlockings across northern Illinois. If those shut down, they send a failure warning to the dispatcher in Omaha, who calls out a maintainer to brave the roads to get to the heater that failed. The forced air ducts would be too long for some of the tracks at Western Avenue.
Metra’s Engineering Director, John Meyer, said that while the hot air blowers are ideal for heating switch points, they aren’t used at A-2 due to the density of the switches there. “With the configuration at A-2, there’s no way to put them in the middle of the plant – you’d have to put pipes across all the tracks and then they’d lose heat.”At one time, similar switch heaters were in use at the throat of North Western Terminal, the facility Metra calls the Ogilvie Transportation Center. They're not a threat to the trains, that despite a big tank of diesel fuel slung under the diesels on the outward end. "Diesel fuel combusts only with pressure and heat, not open flames. Therefore, it is completely safe to operate rolling stock over the switch heaters." That's exactly as you see in the video, a revenue train negotiating the crossovers and double-slips that come in handy when Amtrak detour a California Zephyr over the North Western through DeKalb.
The weather guys are assuring us the polar vortex is going to slink back toward the poles, but the snow season is not over yet. Whenever it snows, the maintainers will be called out and the switch heaters will be lit off if the snow is heavy enough.