MBTA Commuter Rail

The MBTA Commuter Rail system serves as the commuter rail arm of the Massachusetts Bay Transportation Authority's transportation coverage of Greater Boston in the United States. Trains run over of track on 12 lines to 143 stations. It is operated under contract by Keolis.
In, the system had a ridership of, or about per weekday as of, making it the fifth-busiest commuter rail system in the U.S., behind the three New York-area systems and the Chicago-area system. The lines' characteristic purple-trimmed coaches operate as far south as North Kingstown, Rhode Island, and as far north as Newburyport and as far west as Fitchburg, both in Massachusetts.
Trains originate at two major terminals in Boston – South Station and North Station. The only connection between the two halves of the system is the non-revenue Grand Junction Branch. The North–South Rail Link is a proposed tunnel between North Station and South Station to allow through-running service.

Service

Lines

The system consists of twelve lines – four of which have branches – radiating from downtown Boston. Eight "southside" lines terminate at South Station, with four also running through Back Bay station. Four "northside" lines terminate at North Station. The lines vary in length from the Fairmount Line to the Providence/Stoughton Line, with typical lengths in the range. The system has of revenue trackage and covers roughly the eastern third of Massachusetts plus central Rhode Island.

Line	Boston terminal	Outer terminal	Stations	Length	Daily boardings
Greenbush Line	South Station		10		2,691
Kingston Line	South Station		11	– Kingston – Plymouth	4,171
Fall River/New Bedford Line	South Station		15	– Fall River – New Bedford	5,261
Fairmount Line	South Station		9		2,843
Providence/Stoughton Line	South Station		18	– Wickford Junction – Stoughton	17,648
Franklin/Foxboro Line	South Station		18	– Forge Park/495 – Foxboro	8,771
Needham Line	South Station		12		4,881
Framingham/Worcester Line	South Station		18		10,606
Fitchburg Line	North Station		19		4,829
Lowell Line	North Station		9		6,485
Haverhill Line	North Station		15		5,806
Newburyport/Rockport Line	North Station		19	– Newburyport – Rockport	11,333

Most lines do not share trackage outside the Boston terminal areas, with several exceptions. The Providence/Stoughton Line and Franklin/Foxboro Line both use the Northeast Corridor between and South Station, with the Needham Line also sharing the tracks between and South Station. The Fall River/New Bedford Line, Kingston Line, and Greenbush Line all use the Old Colony mainline between South Station and Braintree. The Haverhill Line and Newburyport/Rockport Line share tracks between North Station and near. A small number of Haverhill Line trains use the inner Lowell Line and the Wildcat Branch, while some Franklin/Foxboro Line trains use the Fairmount Line rather than the Northeast Corridor. Several Amtrak intercity routes run on MBTA tracks: the and over the Providence/Stoughton Line, the over the Framingham/Worcester Line, and the over portions of the Lowell and Haverhill lines. Private companies also operate freight service over much of the system.

Stations

, there are 143 active stations – 56 northside and 87 southside. Five additional stations are indefinitely closed due to service cuts during the COVID-19 pandemic. Several other stations are planned. South Station, North Station, and Back Bay all have MBTA subway and Amtrak connections; nine other stations have subway connections, and six others have Amtrak connections.
Stations range in size from small platforms like to the sprawling downtown terminals. Most stations outside downtown Boston have one or two side platforms or a single island platform. Standard MBTA platforms are about long – enough for a nine-car train – and a minimum of wide for side platforms and wide for island platforms. 122 active stations are accessible, including all terminals and all stations with rapid transit connections; 21 are not. The MBTA uses -high platforms for accessible level boarding, as is standard in the northeastern United States. Some accessible stations have full-length high platforms for accessible boarding on all cars; others only have "mini-high" platforms about long – which allow for level boarding on two cars – with the rest of the platform length not accessible.

Operations

The MBTA Commuter Rail system is operated by Keolis Commuter Services – a subsidiary of French company Keolis – under contract to the MBTA. The MBTA owns all passenger equipment and most stations. Most trackage is also owned by the MBTA. The Massachusetts Department of Transportation owns several portions of the Framingham/Worcester Line as well as the Grand Junction Branch, which is used for non-revenue equipment moves between the northside and southside lines. Pan Am Southern owns the section of the Fitchburg Line between and Wachusett, while Amtrak owns the section of the Northeast Corridor in Rhode Island.
Most lines operate on regular headways, though some have additional service at peak hours. Service levels vary by lines: the Greenbush and Kingston lines have 13 round trips on weekdays, while the Providence/Stoughton Line has 37. Running times vary from 30 minutes on the Fairmount Line to nearly 120 minutes for some Providence/Stoughton Line trips, with 60–75 minutes typical. Most trains stop at all stations on the line; some stations have limited service, and peak-hour express trains operate on several lines. Several lines additionally have some short turn service. The CapeFlyer, a seasonal weekend-only service to Cape Cod, operates using MBTA equipment over the Middleborough/Lakeville Line plus the Cape Main Line. Special express service to Foxboro station is operated during New England Patriots home games and some other events at Gillette Stadium. It runs from South Station via the Franklin/Foxboro Line, and from Providence via the Providence/Stoughton Line. During the winter, one "ski train" round trip of the Fitchburg Line operates with a bicycle car on weekends and Wednesday evenings, with a shuttle bus to Wachusett Mountain.
All MBTA commuter rail service is provided by push-pull trains powered by diesel locomotives. Maximum speed for trains is, though some lines have lower limits. The entire system is signalled and operates with Positive Train Control using the Advanced Civil Speed Enforcement System. All lines have cab signals for automatic train control. The MBTA is a member of the Northeast Operating Rules Advisory Committee and uses its operating rules. Most portions of the system operate under NORAC rules 261 and 562, which allow bidirectional train movements on every track. Most lines are either double track, or single track with passing sidings; portions of the Northeast Corridor have three or four tracks.

Freight service

Freight service is operated over most of the MBTA Commuter Rail system by several private railroads. CSX Transportation operates freight on most southside lines, of which the outer portion of the Worcester Line has the most freight traffic. Massachusetts Coastal Railroad operates south of Middleborough on the Fall River/New Bedford Line. The Fore River Railroad operates between Braintree Yard and East Braintree on the Old Colony mainline and the Greenbush Line. The Providence and Worcester Railroad shares tracks with Providence/Stoughton Line trains between Providence and Wickford Junction; it uses a freight-only track between Providence and Central Falls. No freight operates on the Needham Line, the Northeast Corridor between Readville and Back Bay, the Old Colony mainline between Boston and the Greenbush Line junction in Braintree, the Kingston Line, and most of the Greenbush Line.
CSX also operates on most northside lines; prior to its 2022 purchase by CSX, Pan Am Railways operated over these lines. The Berkshire and Eastern Railroad operates over the Fitchburg Line west of Ayer. Their combined Freight Main Line between Mechanicville, New York, and Mattawamkeag, Maine, shares tracks with sections of the Fitchburg, Lowell, and Haverhill lines. No freight service is operated over the Newburyport/Rockport Line north of.
Weight limits and loading gauge vary across the system. The full Framingham/Worcester line is rated for car weights of, sections of lines that are part of the Freight Main Line for, and other lines for lower weights. The western portion of the Framingham/Worcester Line and the southern section of the Providence/Stoughton line can accommodate cars up to . The Fitchburg Line west of Ayer can accommodate cars up to , while most of the other northside lines can accommodate up to . The inner Fitchburg and Newburyport/Rockport Lines, and the southside except for the outer Framingham/Worcester Line, have height restrictions smaller than Plate F.

Fares

MBTA Commuter Rail uses a zone fare system, with fares increasing with distance. Zone 1A includes the downtown terminals and other inner core stations up to about from downtown. Ten additional zones, numbered 1 through 10, extend outwards from Boston. Each zone is about 5 miles, with most outer terminals in zones 6 through 8. Only two stations use further zones: in Zone 9, and in Zone 10. Zone 1A fares are identical to MBTA subway fares., one-way fares within Zone 1A are $2.40, while fares between further zones and Zone 1A range from $6.50 for Zone 1 to $13.25 for Zone 10. Trips that do not enter Zone 1A have less expensive interzone fares; as of 2024, these range from $2.75 for travel within a single zone to $7.25 for travel between Zone 1 and Zone 10.
Fares can be purchased on the MBTA mTicket app, at automatic vending machines located at major stations, from businesses near some stations, or from conductors on board trains. Discounted passes include monthly passes, "flex passes" valid for five 24-hour periods, and $10 passes offering unlimited travel on a single weekend. As with other MBTA services, discounted fares and passes are available for several groups including disabled passengers, passengers over age 65, and students attending certain schools. Foxboro special event services and the CapeFlyer have separate fares; regular MBTA fares and passes are not valid. Fares are collected by train conductors; while fare evasion is explicitly illegal under state law, it is not criminal. Fare gates have been installed at North Station and South Station, with plans for installation at Back Bay and Ruggles. The second-generation MBTA fare collection system will standardize fare media across modes, including commuter rail.