A Westbound CTA Green Line train makes its way West out of downtown Chicago.

A four-car Chicago Transit Authority commuter train crosses the diamonds at Tower 18 on the elevated “L” rapid transit railway above Lake and Wells Streets on November 8, 2018. This interestin... (more)

Green Line train #609 approaching Clinton while crossing over the Chicago River

A southbound CTA Red Line train emerges from underneath I-90 during a snowstorm

A CTA Green Line train passes over the Chicago River above Lake Street. The Green Line uses some of the oldest infrastructure in the "L" system, with some of it dating back to 1892.

A Red Line train to 95th speeds past Armitage on the express tracks. The train will shortly descend into the subway to traverse downtown.

A set of Bombardier 5000 Series cars clatters over the diamonds at Chicago Transit Authority’s busy junction at Tower 18 on the elevated “L” rapid transit railway above Lake and Wells Street... (more)

Chicago Transit Authority car No. 5127 crosses the diamonds at Tower 18 on the elevated “L” rapid transit railway above Lake and Wells Streets on November 8, 2018. This junction is still consi... (more)

For the Third Year in a row Chicago Transit Authority wrapped 4 Red line 5000 series Car into LGBTQ Pride colors to celebrate Pride month in June.

Chicago Transit Authority train 5442 passes the interlocking at CTA Tower 18 on the elevated routes over Lake Street and Wells Street in Chicago, Illinois.

Two Chicago Transit Authority trains negotiate the interlocking at CTA Tower 18 on the elevated routes over Lake Street and Wells Street in Chicago, Illinois, on November 8, 2018. This crossing is... (more)

A Harlem bound Green Line train arrives at Cermak-McCormick Place.

A Chicago Transit Authority train heads east on the elevated railway above Lake Street through a canyon of skyscrapers in Chicago, Illinois, on November 8, 2018.

Non-stop action at possibly the busiest rail junction in the world. Most of the people of Chicago never see this view of the action, but they sure do hear it when trains rumble across it!!

A Pink Line train pounds the Diamonds at Tower 18 Interlocking as it begins to do its turn around the Chicago Loop.