WTF rides the rails in the City of Brotherly Love. While there, Riley teams up with crews of the nation's fifth largest public transportation system, Philadelphia's SEPTA, to find out what it takes to keep 2,200 miles of tracks safely running. The team must replace a three-mile section of 80-year-old high-voltage wire. It's a risky operation, with live wires just an arms reach away. Then, Riley heads to the garage to work on a train with a malfunctioning automatic control system.