A CTA Purple Line train passes through Sheridan Station and immediately meets another Purple Line train heading in the opposite direction. Though the first train is an express and does not work Sheridan, the second train does make a stop. Sheridan sees Purple Line trains using the outer tracks during weekday rush hour service, but they only work Sheridan when there are games or other events at Wrigley Field (as was the case when this was filmed) | Trainiac Productions

POV: You’re riding on a CTA Brown Line train and pass through Tower 18 Interlocking 🚈 Often referred to as “the busiest railroad junction in the world,” Tower 18 Interlocking is responsible for the safe passage of trains on the CTA’s Brown, Green, Orange, Pink and Purple Lines as they navigate the Loop. The tower structure seen in this video is the third version to exist here. The first was built in 1900 (as far as I can ascertain), the second in 1969, and this one in 2010. There’s an immense a