Boston South Station (MP 228.7) is in the southeast corner of Atlantic Avenue and Summer Street, with the curved frontage of the two-storey headhouse on the corner, and the rear of the headhouse at a 45-degree angle behind, even though the tracks are parallel to Atlantic Avenue. There are five full-length platforms (tracks 1-10), and two shorter ones, for tracks 11-13, serving thirteen tracks, with an air-rights building overhead on the middle section of the platforms, and a road bridge overhead to the south of that building, reducing to six tracks in the station throat, which is also South Junction/Tower 1 (MP 228.5), where four tracks continue south-southwest, bridging over the Fort Point Channel, while five tracks curve west, CETC, overhead electrification, with speed limit 15 mph for passenger trains and 10 mph for freights.