A 112-year-old serpentine stretch of wooden track, switches and traffic signals regulates Chicago Transit Authority (CTA) elevated trains just north of the Belmont Red and Brown line station on the north side.
The two lines converge at these S curves, creating a longtime choke point of train traffic. During rush hour, Purple line trains, which run express up to Evanston, Ill., join the jumble on the same tracks as the Red line trains.