In Chicago, certain areas of the train tracks are lit on fire with gas-powered pumps to keep the movable parts of the switches from freezing in winter.
How do they do this at intersections and prevent car tires from being lit ablaze? Or are they not at intersections?
According to your article, these fires are used at switches in the track. You don’t have a switch and an intersection at the same place.
This. It’s the switch points (the moving parts) which need to be kept thawed; the heaters aren’t generally used on rails other than at switches – and, as noted, because they are movable, the railroads likely try to not ever have switches (and, thus, the heaters) located at grade (road) crossings.
Most of the switch heaters in Chicago have now been fitted with ones that blow hot air. The ones that go viral every January are at interlocking A-2, located on this embankment.
I think there are a few other places around the city, but most of Chicago has very few grade crossings. In the early 20th century, the city forced the railroads to elevate their tracks to reduce deaths from grade crossing accidents.
Prior to COVID, I’d take the BNSF Metra line in to work in downtown Chicago – that line approaches Chicago Union Station from the south.
The area south of Union Station has dozens of tracks, and dozens of switches, many of which still use the flame heaters in the winter (or, at least, did as of a couple of years ago). Though those tracks are at ground level, they’re also in an area where no streets cross them.
OK - but what about the wooden railroad ties at the switches? Why aren’t they set on fire?
It seems that a creosoted tie would burn like the proverbial shingle factory.
And why don’t fusees (used to protect trains from rear-end collisions) set the ties on fire?
I’ve seen an increasing number of concrete ties, so perhaps that’s what’s in place at these switches?
Old-style ties might be wood infused with creosote, but they’re also big. There’s not much surface area for their volume. It’s a lot harder to light a big fat log or tie than small twigs.
Concrete ties are not very common in the Chicago region; in fact, US railroads have in general not had particularly cost-effective results from them.
The gas jets used for these switches are pointed pretty specifically at the rails. They’re not just bonfires built on the right-of-way. Metra says, though, that a few ties do get scorched and need to be replaced each year.
Is the track in these areas bolted track or CWR (welded rail)? I wonder if thermal expansion causes any problems? Switch points have some fairly close tolerances. It didn’t look like the trains in the video were running at restricted speeds.
Even where concrete ties are common, complicated switches still tend to use wood ties because they’re easier to build. Also, warm air rises, so most of the heat is going up and away from the ties.
Part of the reason they’re doing it is to combat thermal contraction of the rails in cold weather (which exerts tension on the tracks and can pull joints apart)