Overview: Approaching Philadelphia from the south, intercity, commuter, and freight trains reach a diversion point at Phil Interlocking. Amtrak trains remain on the NEC main line to serve 30th Street Station’s below-ground station platforms. Commuter trains divert off tracks to the west that serve SEPTA’s upper-level 30th Street Station concourse. Freight trains divert off tracks to the east that fly over the 30th Street Station complex.
SEPTA’s Airport Line approaches this congested point of divergence from the east, crossing over the Corridor on a single-track flyover bridge that ramps down on the west side of the NEC at Phil Interlocking. Though the single-track flyover limits frequency of service on the Airport Line because it is shared by both northbound and southbound trains, it does prevent at-grade crossings of the NEC. However, northbound Wilmington/Newark trains do not have access to this flyover and must cross over the entire NEC main line at grade. These crossings require significant windows in Amtrak’s schedule in both directions and can create traffic jams for all services. Improvements under consideration would expand the flyover and fully separate SEPTA’s operations from Amtrak on the critical approach to 30th Street Station. These investments would reduce delays in and out of Philadelphia’s major intermodal hub, increase scheduling flexibility, and create opportunities for growth in commuter service.