Willows to Fitchburg

From the junction at CPF-WL/Willows (MP 313.77/33.72), where teh Fitchburg Line from Boston trails into the south side of the former Boston & Maine Main Line from Mattawamkeag, the line heads west, Two Main Tracks, CTC, maximum speed 60 mph for passenger trains and 40 mph for freight trains, past the wye on the south side with the former B&M line to Worcester at CPF-AY (MP 315.75/35.75), where a 30 mph speed restriction starts, with a 20 mph head-end restriction on Track 1, an erstwhile line to Nashua once headed north, and there are connectors to intermodal and autorack terminals, the passenger station at Ayer (MP 316.07/36.07), and crossovers (10 mph on the crossovers at Moore's (MP 316.22/36.22), where a branch to West Groton heads away northwest, there is a 20 mph head-end speed restriction on track 2, after which all restrictions end and full line speeds prevail.

There is a passenger station at Shirley (MP 319.43/39.43), where the line turns southwest, past CPF-Slab City (MP 320.17/40.17), with a 55 mph passenger speed restriction on the curve from MP 41.57 to MP 41.76, northwest with a 45 mph passenger speed restriction on the curve between MP 43 and MP 43.54, past the passenger station at North Leominster, Ox (MP 325.23/45.34), and the junction with the former New Haven line from Framingham, trailing in from the south-southeast at East Fitchburg, CPF-FG (MP 328.10/48.10), and west, with a 35 mph speed restriction on curves from MP 48.80, to Fitchburg (MP 329.55/49.55), where there is a passenger station and MBTA service from Boston North Station ends.