of the fourth car (M3 #818) followed the third car, while the rear truck of the fourth car took the diverging track, causing the car to shear halfway upon striking the steel pillars separating the tracks beyond the switch. On February 21, 2017, a train derailed at the 69th Street Station loop after it crashed into a stopped train and caused a third train on an adjacent track to derail, seriously injuring one of the operators and injuring three others. Stations All connections, unless otherwise noted, are operated by SEPTA. References Further reading External links Market-Frankford Line on SEPTA website NYCsubway.org – SEPTA Market–Frankford Line Stan's Railpix – Septa Photo Gallery Page 3* SEPTA Market–Frankford Line Pictures West Philadelphia Collaborative History – The Market Street Elevated ("The El") Railway lines opened in 1907 Underground rapid transit in the United States 5 ft 2¼ in gauge railways in the United States Historic American Engineering Record in Philadelphia 600 V DC railway electrification 700 V DC railway electrification 1907 establishments in Pennsylvania Railway lines in highway medians