This is awesome. I was a regular Metra UP-West line rider when I lived in Chicago and used to see this on evenings just like the one in the image. The interlocking (a railroad junction) A-2 was always a hoot to pass through at night in the winter (which would describe my usual 5:09 departure from the North Western Station) when they had these going.

You could tell who was a regular rider and who was a tourist – “OMG! THE TRACKS ARE ON FIRE!!!”

Um, actually, no.

Well, actually yes, but it’s OK.

Generally, heaters like this have been replaced with gas-fired hot air blowers to keep switches clear but, like position-light and color-position-light signals — both shown here! — they’ve mostly disappeared.

This image is looking almost due east from Western Ave, which passes under just about the spot where there is a gap in the fires.  Metra UP-West  trains use the four ex-C&NW tracks to the left that start at what was the North Western station.  The Metra Milwaukee West- and North Districts, and the Metra North Central Service (and Amtrak’s Empire Builder and Hiawathas) all cross from the right in the distance, on three (or four?) tracks that started a Union Station, through the interlocking and then head NW using ex-Milwaukee Road tracks which would be to the left of the photographer. 

The Pennsylvania position-light signal (three yellow bulbs in a vertical configuration indicating “clear”) is there because the Pennsy’s Panhandle route also joined this line from the right just behind the photographer.  Their passenger trains from that line once made their way to Union Station this way although most Pennsy trains (like the Broadway Ltd) took a different route to get to the south side of Union Station.

There is a plan to move this interlocking (“A-2”) a mile or so in the direction of the image towards the Loop (making it “A-1”) so that they can have more room to spread things out.  This should mean that trains will be able to get through the junction a little faster.  Trains from Union Station crossing here are limited to about 15 mph. 

Oh, and behind the photographer is the Metra California Ave yard that maintains cars and engines from the UP lines and behind and to the left, is the Metra Western Ave yard that does the same for the Milwaukee Districts and North Central Service.

Here’s a map and link to lots of nerd pics.