North–South Rail Link

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North–South Rail Link
South Station from Dewey Square, August 2012.jpg
South Station, the southern terminus of the proposed tunnel
LocaleBoston, Massachusetts
TerminiSouth Station
North Station
Stations2 or 3 proposed
TypeCommuter Rail
Line length5 miles (8.0 km)[1]:68
Number of tracks2 or 4
Track gauge4 ft 8 12 in (1,435 mm) standard gauge
The North–South Rail Link would close a 1.5-mile (2.4 km) gap at the center of the regional rail network.

The North–South Rail Link (NSRL) is a proposed rail tunnel, or pair of tunnels, that would connect North Station and South Station in downtown Boston, Massachusetts.[2] The project would build new underground stations near the existing stations, connect them with about 1.5 miles (2.4 km) of tunnels, and add other tunnels to link up with existing surface tracks.[1]

The NSRL would connect Amtrak and MBTA Commuter Rail lines that terminate either at North or South Station. For MBTA, it would link northern lines to South Station, Back Bay Station, and lines beyond Back Bay, including the Framingham/Worcester Line and the Northeast Corridor; one option under consideration would also link to commuter lines to the south. The project would also link Amtrak's various trains into and out of the city; for example, the Downeaster line from Maine currently has no direct connection with Northeast Corridor trains to New York City and beyond.[3]

In June 2018, MassDOT's North South Rail Link Feasibility Reassessment described the costs and benefits of several alternatives, including adding tunnels in various configurations or doing nothing. The tunnel options included a $21.5 billion four-track maximum-service plan and three double-track routes ranging in cost from $12.3 billion to $14.7 billion. (These costs are in 2028 dollars and include purchasing additional rolling stock, other required infrastructure improvements, and a 3.5% annual inflation.) The presentation noted that a planned expansion of South Station would cost an estimated $4.7 billion, not including the purchase of rolling stock, electrifying the system, and renovating Tower 1.[1]

Historical connections[edit]

From 1872 to 1969, the freight-only Union Freight Railroad provided a direct, street running connection between most of the south-side and north-side railroads, and served local customers and wharves in between.

From 1901 to 1938, the Atlantic Avenue Elevated provided direct passenger service past North and South Stations. The elevated trackage was not connected to any of the conventional railroad tracks.

Present connections[edit]

MBTA commuter rail map as of 2018 showing separation of northern and southern segments. Amtrak's Downeaster to Maine terminates at North Station; all other Amtrak trains terminate at South Station.

Public transit connects North Station to South Station only indirectly, through two of the MBTA Subway system's quartet of hub stations. A trip between the two commuter rail stations requires taking two subway lines, either the Green Line and the Red Line through their shared Park Street station, or the Orange Line and the Red Line's shared Downtown Crossing station. The underground Winter Street Concourse connects the upper levels of Park Street and Downtown Crossing stations. Amtrak recommends that passengers with young children or much luggage take a taxi between the stations.[4]

It is possible to traverse the gap directly via the Orange Line from Back Bay Station to North Station, but it requires seven stops and not all of the southern lines pass through Back Bay; the Old Colony Lines, and Fairmount Line on the Commuter Rail do not. The Orange Line also provides a connection for Amtrak passengers who want to transfer between the Northeast Corridor and the Downeaster. However, North Station passengers add significantly to Orange Line congestion.[1]:12 Similarly, it is possible to connect between South Station and the Fitchburg Line via the Red Line at Porter station. Passengers on the Newburyport/Rockport Line can also take the Silver Line from Chelsea (Bellingham Square). The weekday-only MBTA bus #4 connects the two stations. The North–South Rail Link is proposed to fill all these awkward gaps in service, with direct connections requiring no transfers.

2018 NSRL feasibility study[edit]

The Back Bay portal, serving the Northeast Corridor and Worcester Line, would be located in this area east of Tremont Street

In June 2018, MassDOT released a North South Rail Link Feasibility Reassessment presentation that described several tunnel alternatives.[1] The state began soliciting bids for a $2 million feasibility study on March 1, 2017. This study had been pushed for by the North-South Rail Link Working Group. The working group, NSRL supporters, includes Senator Ed Markey, Representatives Niki Tsongas and Katherine Clark, with Representative Seth Moulton leading the effort. It also includes more than half of Massachusetts mayors.[5]


The 2018 MassDOT feasibility study analyzed four possible options. Two options would run under the Central Artery (I-93), one option with two tracks and the other, more expensive, with four. The other two options, each with two tracks, would tunnel under downtown Boston several blocks west of the Artery. All the proposals connect the northern commuter rail lines with South Station and then to Back Bay and lines to the west. Only the four-track option would connect North Station with the Fairmount Line south of South Station. Under all the proposals, the Old Colony Lines would continue to terminate at the South Station surface platforms. The existing North Station and its surface platforms could be eliminated under all four options, making the area available for redevelopment.[1]:23

Central Artery four-track[edit]

The most ambitious option, it is the only one that includes a new Central station (or Union Station) near its midpoint, and the only one with a rail tunnel connection to the Fairmount Line. North Station would be underground near the present station. The line would be constructed using two 41-foot TBM tunnels, 125 ft deep, along with cut-and-cover in Fort Point Channel. Underground South Station would be built in Fort Point Channel, east of surface station. Central station would connect to the Blue Line at Aquarium station. The Blue Line is currently the only MBTA rapid transit line with no direct connection to the commuter rail network.[6] Estimated cost: $21.491 billion.[1] :63

Central Artery two-track[edit]

Same route as Central Artery four-track but has no Central station. Constructed using one 41-foot TBM tunnel, 125 ft deep, with cut-and-cover used in Fort Point Channel. Underground South Station would be built in Fort Point Channel, east of surface station. Estimated cost: $12.317 billion.[1] :63

South/Congress alignment[edit]

North Station would be entirely underground and moved several blocks south, to between State and Haymarket Streets; no Central station. Stacked tracks and platforms are incorporated within a single 51-foot TBM bored tunnel, 115 - 130 ft deep. Underground South Station would be north-west of surface station. Estimated cost: $13.181 billion.[1] :63

Pearl/Congress alignment[edit]

North Station would be entirely underground and moved several blocks south, to between State and Haymarket Streets; no Central station. Tracks would be in two 29-foot TBM bored tunnels, 135 - 195 ft deep. Underground South Station would be north of surface station. Estimated cost: $14.388 billion.[1] :63


The tunnels would not be able to handle diesel locomotives and therefore would require the use of dual-mode locomotives or the electrification of several MBTA commuter rail lines. Full electrification of additional rail lines, proposed in earlier studies, could help Massachusetts and the MBTA reach their greenhouse-gas reduction goals, make service more reliable, allow trains to accelerate more quickly, and reduce travel times, but it is expensive and only limited electrification is included in the 2018 proposals. Part of the Fairmount Line would be electrified to allow Amtrak and MBTA Northeast Corridor trains currently routed through Back Bay to reach South Station during construction of the Back Bay portal. The electrified service region would also incorporate the proposed South Coast Rail project's Phase II, which includes electrification to Fall River and New Bedford.[1]:60


North Station platforms

The 2018 feasibility study modeled ridership in 2040 based on various scenarios. In regular service, the two-track options would increase all day boardings to 195,000 compared with 150,000 in the no-build scenario. Assuming an upgrade to all-day peak service, the two-track options would increase all day boardings to 225,000 compared with 195,000 with the South Station expansion.[1]:47 Overall, NSRL would increase commuter rail capacity, in terms of seats to downtown, by 25%.[1]:56

The feasibility study presentation also projected the distribution of destinations for commuters coming from the north in the morning.

NSRL Projected Morning Trips From The North in 2040, Two-Track[1]:52
Destination Passengers Percent
North Station 18,182 67%
South Station 5,477 20.2%
Back Bay 2,712 10%
Through service 771 2.8%
Total 27,142 100%

Potential problems[edit]

The 2018 feasibility study identified several potential problems and risks with the NSRL project:

  • During construction of the Back Bay tunnel portal, required under all options, the MBTA Worcester Line and Amtrak Lake Shore Limited service would have to terminate west of Back Bay station or possibly be rerouted via the Grand Junction Line into North Station. Also some or all Amtrak, Providence, Stoughton, and Franklin Line service would be rerouted via the Fairmount Line into South Station.[1]:20
Porter Square escalators
  • The proposal makes aggressive assumptions about improved passenger loading and unloading times and on how many trains can operate per hour in the tunnels. The proposed train frequency, 17 per hour per direction in the two-track options, is higher than the current Red Line train frequency, and exceeds what has been achieved to date on other systems that use the new positive train control systems required for heavy rail.[1]:41 To maintain the 17 trains/hour frequency, trains would have to arrive to enter the tunnel precisely as scheduled.[1]:40
  • With the NSRL, the MBTA commuter rail system would be highly dependent on the tunnel routes. Any disruption to those routes would affect the entire system.[1]:41
  • While the NSRL design as proposed exceeds National Fire Protection Association NFPA 130 life safety requirements,[1]:35 evacuation of the deep tunnels and stations in case of fire could still be difficult. The deep stations would also cost passengers additional time entering and leaving. Currently Porter Square station, at 105 ft, is the deepest in the MBTA system.[1]:34

Earlier proposals[edit]

There have been several prior proposals to link South Station and North Station by rail.

The earlier leading proposal, called the "Dorchester Avenue Alignment", is similar to the four-track Central Artery alignment in the 2018 study. It would dig two 41-foot-diameter (12 m) deep-bore tunnels beneath Boston, extending beyond the present rail yards north and south of the city. The tunnels would pass about 20 feet beneath the I-90 extension, and would reach their maximum depth of 130 feet (40 m) at a possible Central Station and at North Station.

Carrying a total of up to four tracks, the tunnels would have steep inclines. Trains entering or exiting the tunnels would climb or descend 3% grades, each nearly a mile long.[7]

Because the tunnels would continue well south of downtown, three portals would accommodate separate connections to Back Bay Station to the west, the Old Colony Lines to the south, and the Fairmount Line running southwest. To the north, the tunnels would cross the Charles River about 70 feet (21 m) below its surface (bypassing an existing drawbridge), and connect via portals to the Fitchburg Line and the other northbound rail lines.

The plan would require two or three new underground stations; stations are proposed roughly beneath the current North and South Stations, and possibly a new Central Station near Aquarium Station. Central Station would have an 800-foot (240 m) platform; North Station and South Station would have 1,050-foot (320 m) platforms.

Pilings for a planned high-rise tower at South Station complicate a proposal to put the tunnels directly beneath the present South Station. Instead, the Dorchester Avenue Alignment proposal would move the tracks just east of South Station, and would build an underground facility about 100 feet (30 m) below the surface of the Fort Point Channel at the Summer Street crossing.[8] Tracks at the underground South Station would have a 0.61% incline.

The new Central Station would connect with the Blue Line at its Aquarium station via an underground concourse, as the Blue Line is the only rapid transit line in Boston that does not already connect with either North or South Station. The new station also would eliminate or reduce transfers to the rapid transit system for many commuter rail passengers with destinations in the central part of the business district. This would relieve transit congestion in the downtown core. Like Philadelphia's SEPTA system after the similar Center City Commuter Connection tunnel was built and connected two commuter rail systems, some of Boston's trains would be through-routed from one side of the system to the other. Many services would still terminate at North and South Stations, on existing tracks that do not lead into the tunnels. This could also allow trains to pass parked train cars.

A 2003 DEIR/MIS assumes that about one-third of Amtrak trains to and from points south would be routed through the tunnel, stopping only at South Station, but with a new stop north of Boston at Anderson Regional Transportation Center in Woburn, Massachusetts. The Downeaster service from Maine and New Hampshire was assumed to stop at North Station only, with a direct connection to more southerly service at Anderson RTC rather than Boston. Thus, some operations would continue above ground at North Station and South Station, and all track and facilities would remain in place.[9] The tunnels would not be equipped to handle diesel locomotives, which may not be suited to the planned steep grades and closely spaced stops.[10] That would require the MBTA to buy and run locomotives equipped for electric operation.

Route map[edit]

The map below depicts one of the most extensive proposals made to date. The 2018 feasibility study options do not include a link to the Old Colony and Greenbush lines. Only the four-track option includes a link to the Fairmont Line and a Central station. The surface North Station would be eliminated in two of the options and might not be kept in the other two.

Route map of the North–South Rail Link (Dorchester Avenue Alignment)
Commuter Rail Maintenance Facility
(MBTA employees only)
North Station
Amtrak MBTA.svg MBTA.svg Green Line (MBTA)
Central Station
Blue Line
South Station
Amtrak MBTA.svg MBTA.svg Silver Line (MBTA)
Amtrak NEC; Needham, Franklin,
& Providence/Stoughton Lines
Bass River


In May 2006, the Commonwealth of Massachusetts withdrew its sponsorship of the project due to its high capital cost (projected at several billion dollars, with wide variations depending on which option is chosen). Without matching local funds, the project was ineligible for federal funding, and was no longer listed as an approved project in state and Boston MPO capital plans.

The April 2007 document Journey to 2030: Transportation Plan of the Boston Region Metropolitan Planning Organization said "the MPO feels that a study of the right-of-way requirements should be conducted for preservation of that right-of-way so as to not preclude this project's going forward in the future."[11]

In December 2007, the Federal Railroad Administration was interested in funding this project if the Massachusetts Executive Office of Transportation was interested in sponsoring it.[12]

In August 2009, the project was brought back into the spotlight as a component of the New England transportation plan, a coordinated effort by the six New England states to improve rail transportation infrastructure by competing for the $8 billion allocated for high-speed rail in the American Recovery and Reinvestment Act of 2009.[13]

In December 2011, former Governor Michael S. Dukakis reiterated his long-term support for rail service, saying he had been trying to convince the current Massachusetts administration "to get serious about building a rail link" rather than expand South Station.[14] In January 2014, Dukakis said he would prefer to have the North–South Rail Link named after him, rather than South Station, as the Massachusetts House of Representatives had voted unanimously to do.[15]

In August 2015, former Governors Dukakis and William F. Weld co-wrote an op-ed calling the link "One of the most important and cost-effective investments we can make".[16] Based on their advocacy, MassDOT agreed to fund a $2 million study in February 2016.[17]

In June 2018, MassDOT released a North South Rail Link Feasibility Reassessment presentation that proposed several tunnel alternatives, described above.[1] The state began soliciting bids for the $2 million feasibility study, advocated for by the North-South Rail Link Working Group, in March 2017. The study did not identify a funding source for constructing the NSRL.[5]:6

On September 6, 2018, MassDOT released their draft feasibility reassessment report and asked for public comment by October 19.[18]


As of 2018, the MBTA and Amtrak use the Grand Junction Line for non-revenue vehicle moves between the two sides of their networks. This alternative connection splits from the Framingham/Worcester Line near Boston University and the Mass Turnpike Allston/Brighton exit ramps, and the track then crosses the Charles River into Cambridge. From there, it runs through the East Cambridge neighborhood and into Somerville, where it connects to the commuter rail lines running from North Station, just below the McGrath-O'Brien Highway.

The line is currently single-tracked east of Massachusetts Avenue and slow, with a large number of at-grade crossings. Several of the crossings (e.g. Massachusetts Avenue, several streets around Kendall Square, Cambridge Street, and Gore Street) require trains to come to a near-complete stop before proceeding at their maximum allowed track speed of 10 miles per hour (16 km/h).[19]:12 The line would potentially be served by a new West Station which is proposed as part of the Beacon Park Yard redevelopment.[20]

The Grand Junction corridor has also been proposed as part of the Urban Ring light rail or bus rapid transit project, or a possible pedestrian trail.[19] However, only Worcester Line trains would be directly served, while all other trains from South Station lines would have to detour and reverse all the way to the west of Back Bay and Lansdowne stations to reach the Grand Junction connection.

An above-ground rail link between South and North Stations was once proposed[citation needed] by the Boston-based Association for Public Transportation (which also supports the underground North–South Rail Link). This would eliminate the need to use multiple rapid transit lines to travel between terminals, but would still require two transfers for Amtrak and commuter rail passengers passing through downtown Boston. Unless grade separated, the link would have to operate at slow speed through very congested downtown traffic.

See also[edit]

  • Center City Commuter Connection – a similar tunnel opened in Philadelphia in 1984 to connect two previously-separate rail terminals
  • Crossrail – a similar project in London, England; currently under construction
  • East Side Access – a commuter rail project in New York City with a high-traffic terminal being built deep under Grand Central Terminal
  • Gateway Program (Northeast Corridor) – a proposed commuter rail project in the New York City area with two tunnels between New Jersey and New York Penn Station
  • Oslo Tunnel – a similar project in Oslo, Norway; opened in 1980
  • Picc-Vic tunnel – a similar project in Manchester, England; never built
  • Stuttgart 21 – a railway and urban development project in Stuttgart, Germany including some 30 kilometres (19 miles) of tunnels and 25 kilometres (16 miles) of high-speed lines


  1. ^ a b c d e f g h i j k l m n o p q r s t u "North South Rail Link Feasibility Reassessment" (PDF). MassDOT. June 2018. Retrieved September 4, 2018.
  2. ^ Sigmund, Pete (June 6, 2007). "Triumph, Tragedy Mark Boston's Big Dig Project". Construction Equipment Guide. Retrieved December 10, 2007.
  3. ^ "Amtrak Downeaster Schedule Effective May 1, 2018" (PDF). Amtrak. May 1, 2018. Retrieved October 2, 2018. Amtrak Downeaster trains arrive at Boston’s North Station. All other Amtrak services in Boston depart/arrive at South Station and Back Bay Station.
  4. ^ "Downeaster - the Train between Boston and Portland, ME". Amtrak. Retrieved April 18, 2012. Transfer by taxi is recommended for passengers traveling with significant amounts of luggage or young children.
  5. ^ a b Dungca, Nicole (March 1, 2017). "State asks for bids in $2 million North-South rail link study". The Boston Globe. Retrieved April 16, 2017.
  6. ^ "North South Rail Link Operations Study" (PDF).
  7. ^ MBTA, et al., North South Rail Link Project, Major Investment Study, vol. I, figure 2.5–7 (June 2003).
  8. ^ MBTA, et al., North South Rail Link Project, Major Investment Study, vol. I, figure 2.5-4 (June 2003).
  9. ^ MBTA, et al., North South Rail Link Project, Major Investment Study, vol. I, figure 2-38 (June 2003).
  10. ^ MBTA, et al., North South Rail Link Project, Major Investment Study, vol. I, 2–36 (June 2003).
  11. ^ "Long-Range Transportation Plan - Archive". Boston Region MPO. Retrieved March 31, 2015.(see page #2–10)
  12. ^ "NSRL Citizens Advisory Committee Letter to EOT" (PDF). Archived from the original (PDF) on July 25, 2008. Retrieved January 12, 2008.
  13. ^ Dukakis, Michael S.; O'Brien, Robert B. (August 23, 2009). "Finally, a rail plan for New England". The Boston Globe.
  14. ^ Grillo, Thomas (December 16, 2011). "South Station expansion chugging along". Boston Business Journal. Retrieved December 23, 2011.
  15. ^ Sweet, Laurel (January 31, 2014). "Michael Dukakis decries terminal honor?". Boston Herald.
  16. ^ Dukakis, Michael S.; Weld, William F. (August 18, 2015). "Finally, a rail plan for New England". The Boston Globe.
  17. ^ Leung, Shirley (February 23, 2016). "North-South Rail Link gets another look". Boston Globe. Retrieved February 23, 2016.
  18. ^ "The North South Rail Link Feasibility Reassessment Draft Report Documents are now available" (Press release). Massachusetts Department of Transportation. September 6, 2018. Retrieved September 19, 2018.
  19. ^ a b "City of Cambridge, Mass.: Grand Junction Rail-with-Trail Feasibility Study – Oct. 2006" (PDF).
  20. ^ Allston I90 Interchange Improvement Project, MassDOT

Further reading[edit]

External links[edit]