Tower A to Wilmington

From the interlocking at Tower A (MP 0.3), on the north bank of the river, where there are crossovers and the lines split three ways: the two-track Fitchburg Route Main Line (Fitchburg Line) heading west-northwest; the two-track New Hampshire Route Main Line (Lowell Line), continuing northwest; and the three-track combined Eastern/Western Route Main Lines (Newburyport/Rockport Line and Haverhill Line) heading north-northwest, the New Hampshire Route Main Line (Lowell Line) heads northwest, Two Main Tracks, CTC, maximum speed 60 mph for passenger trains and 40 mph for freight trains, but local restriction 35 mph (increasing from 10 mph south of Tower A), with carriage sidings to the west, past a through truss bridge carrying the line over a connecting track, signal 1.8 (MP 1.8), where the speed restriction ends and full line speeds prevail, Mystic Junction (MP 1.9), where there is a spur from Track 1 to Yard 10. the location of an erstwhile flat crossing with a CSX freight line between Beacon Park Yard and East Boston, MP 2.2, where there is a spur from Track 2 to Yard 8, a road bridge overhead, signals, a road bridge overhead, and the interlocking at Somerville Junction (MP 3.2), where 2MT, CTC, ends and Double Track, Rule 251 (current-of-traffic) Automatic Block Signals start, with Track 1 (to the east) northbound and Track 2 (to the west) southbound), a line once headed away west to North Cambridge, and the line turns north, past a bridge over a street, two road bridges overhead, a bridge over a street, and more signals.

There is a road crossing at Canal Street (MP 3.5), where a 40 mph speed restriction for passenger trains, and 30 mph for freight trains, begins, and the MBTA passenger station at Tufts College (MP 4.0), and the line turns northwest, past Medford (MP 4.6), a grade crossing with Canal Street (MP 5.3), a grade crossing with High Street (MP 5.4), a street alongside to the east, and the MBTA passenger station at West Medford (MP 5.5), curving gradually around to just east of due north, with two lakes to the west, past the road bridge overhead at Grove Street (MP 6.7), where full line speeds prevail, an embankment, a bridge over a river, the MBTA passenger station with two side platforms and shelters on the bridge, at Wedgemere (MP 7.3), a bridge over a street intersection, a street alongside to the east, two bridges over streets, and the passenger station, signals, and interlocking at Winchester (MP 7.8), where 2MT, CTC, resumes, and an erstwhile line once left to the north-northwest to run through Woburn.

The remaining line passes Swanton Street (MP 8.2), where there is a spur from Track 2 to Swanton Street Yard, and turns just west of due north, past a cemetery to the east, MP 9.1, where there is a spur from Track 2 to Montvale Yard, a road bridge overhead ("9/910"), MP 9.7, where there is a spur from Track 2 to the other end of Montvale Yard, the 2,205 ft. siding and junction (Track 1) with the (former Guilford RR) Stoneham Branch on the east side at Montvale (MP 9.8),  a road alongside to the east, the MBTA passenger station, with two side platforms with shelters at Lechmere (MP 11.0), MP 11.2, where there is a spur from Track 2 to Rothstein,  extra track on the east side, a woody cutting, the MBTA passenger station, with two side platforms with shelters, at Mishawum (MP 11.6), a road bridge overhead, the interlocking at Mishawum Interlocking (MP 11.9),  the line taking the north side of a wye at Mishawum.

There is an "Interstate" bridging overhead, the 2,230 ft. Southbound Passing Siding (MP 12.5-MP 12.9) off Track 2 at South Wilmington (MP 12.7), a passenger station with two side platforms and peaked-roof sheds, a turn north-northwest, MP 13.3, where there is a spur off Track 1 to Crusader Paper, MP 13.9, where there is a spur off Track 1 to Dragon Cement, the MBTA passenger station with an island and two side platforms at Anderson RTC, where Amtrak makes its Woburn stop, signals just north of the station, crossovers, Woburn Junction (MP 14.0), where the erstwhile line through Woburn once trailed back in on the west side, a road bridge overhead, a wooded area, a road bridge overhead, a private grade crossing for Sweetheart Plastic (MP 14.9), signals, MP 14.9, where there is a spur off Track 1 to The Extension Track, a street to the east, the MBTA passenger station with two side platforms at Wilmington, and the 2,770 ft. siding and junction with the Wildcat Branch at Wilmington (MP 15.2), where the Lowell Line turns northwest and the Wildcat Branch heads north.