The freight track continues east from North Ave yard separate from the passenger mains, and in places I think is not always at the same full-height elevation as the passenger mains. Two running tracks head timetable east, merge into one at Division (just past the old Chicago Fish House spur--now a Lexus dealer), and split again at Augusta as they head away from the passenger mains.
At the point where it splits away (August and Racine), the freight alignment begins descending to ground level to reach Grand Ave. Yard. The north track (by compass) is known as the Wall Track, and the south track is the Beer Lead. Just east of Elston, a spur used to head off the Wall Track to reach Chicago Paperboard, and another split off at Sangamon to reach Material Service. Material Service is more or less across the river from International Salt at the south end of the Goose Island Cherry St. Spur, but MS has received all of its stone via barge for at least the last 25 years.
The Beer Lead remained primarily to serve the Tribune and Sun-Times printing plants, but prior to the introduction of push-pull scoots, it lead to a ground-level storage yard for Wisconsin Division scoots. Around 1980, the Tribune built its plant on the site of the former coach yard because it was next to the river, and the Tribune had dreams of receiving newsprint via its own fleet of lake boats/barges (not sure which--never seen a good reference). The boats were never used, and everything comes in via rail. I\'m genuinely confused as to why the Sun-Times seemed to be able to handle 6-12 cars of paper/week, and the Tribune seems to handle 20-30 or better. Anyway, prior to moving, the Trib used to publish out of a building along the North Branch, with a separate warehouse building several blocks away. The newsprint was moved between the two using a short stretch of the old Chicago Tunnel Company, hauling the paper in 12\" gauge cars. Two extra rails were added to the CTC track, and the loaded cars were heavy enough to coast all the way from the warehouse down to the printing plant. Never seen any good photos of this operation either.
The track you are looking at in the photos appears to be the Sipi metals lead. The two tracks in the foreground with jointed rail are the freight leads out of the east end of North Ave.