Two Intersecting Routes, and a Spur

Philadelphia's heavy rail system consists of two major lines which intersect under downtown, and a spur to one of them.  The Market-Frankford Subway-El runs from 69th St. Terminal west of center city along Market St., first on elevated trackage, and then in subway closer to and under downtown.  It emerges again to the northeast of center city, and ends at the Frankford Transportation Center.  The Broad St. Subway runs mostly below-ground and generally north-south.  Its Ridge Spur branches off to end at 8th/Market downtown, to the east of the main line. 

In this view an outbound Market-Frankford train has discharged all of its passengers at the 69th St. Terminal.  Soon the doors will shut, and the train will continue on to turn in a tight-radius loop for the return run.