Green Line Extension Options

In the wake of massive cost overruns piled on top of already absurd costs, the State of Massachusetts has made it clear that fully canceling the much-delayed extension of the Green Line into Somerville is on the table. The challenge remains that the state, as Conservation Law Foundation attorney Rafael Mares makes clear in the WBUR article linked above, is under a legal mandate to build the Green Line extension (GLX, as it is popularly known) stemming from a CLF lawsuit over air quality impacts of the Big Dig project. The state, for its part, insists that should they choose that course, substituting another project is fully legal.


Map of GLX, via WBUR and MBTA

Let’s turn to the full text of the agreement (here, section 7.36). First, we see that GLX was supposed to be open already (and this is a revised, 2007 agreement after earlier delays):

(i) Before December 31, 2014, construction of the following facilities shall be completed and opened to full public use: 1. The Green Line Extension from Lechmere Station to Medford Hillside; and 2. The Green Line Union Square spur of the Green Line Extension to Medford Hillside….

So much for that. The agreement says that the state is supposed to provide interim air quality improvement options in the meantime, but who knows if that’s really happening. What happens if the state decides one of the legally mandated projects isn’t worth building?

(5) Substitute Transit System Improvement Projects. (a) Following MassDOT’s completion of the requirements of 310 CMR 7.36(2)(h)1. and (3)(a) through (c), MassDOT may propose substitute projects for projects required by 310 CMR 7.36(2)(h)1. and (i) provided that: (b) Substitute projects shall be projects that enhance or improve existing public transit service, or provide new transit service in the areas listed in 310 CMR 7.36(5)(c) and (d). (c) Substitute projects proposed for the Fairmount Line project shall be within the Dorchester, Hyde Park, Mattapan, and Roxbury neighborhoods of the City of Boston. (d) Substitute projects proposed for the Green Line Extension and the Green Line Union Square spur of the Green Line Extension to Medford Hillside shall be within the municipalities of Boston, Cambridge, Somerville, and Medford…

(e) Proposed substitute shall be prioritized for funding in the Regional Transportation Plan for the Boston Region and the Transportation Improvement Program of the Boston MPO. (f) MassDOT shall submit to the Department a proposed project substitution determination that includes the following information: 1. The reasons for seeking a project substitution; 2. The proposed substitute project(s) that will be implemented and a proposed project implementation schedule that meets the requirements of 310 CMR 7.36(2)(h)1. and 310 CMR 7.36(3); 3. A demonstration that the proposed substitute project will achieve 110% of the emission reductions of NMHC, CO and NOx that would have been achieved had all components of the project required by 310 CMR 7.36(2)(h)1. and (i) been completed; and 4. The interim emission reduction offset projects or measures that will be implemented until the substitute project(s) is completed. Such interim emission offset projects or measures shall achieve emission reductions of NMHC, CO and NOx equal to or greater than the emission reductions that would have been achieved had all components of the project been completed by the deadlines established pursuant to 310 CMR 7.36(2)(h)1. and (i).

The two primary requirements for substitution are that the substitution project a) cover the same municipalities that GLX would benefit and b) would provide 110% of the air quality benefits. The latter shouldn’t be particularly hard to achieve; air-quality benefits can be somewhat fungible. The former is more challenging, and complicated by the ambiguous wording of the legal document: does a substitute project need to serve all of Boston, Cambridge, Somerville, and Medford, or just be located in one of those municipalities? It’s not hard to imagine that that ambiguity could become a point of conflict between GLX advocates, CLF, and the state.

IF the state decides to cancel GLX–and just to be clear, I’m not advocating for that, this is more of a thought experiment–what are the options? For a baseline, GLX is expected to carry 45,000 riders per day by 2030.

This has been an open topic of discussion on Twitter over the last couple of days. Here are some of the ideas that have popped up (but don’t take any of this spitballing as evidence these people support cancelling GLX):

Modernizing Commuter Rail Service

One of the major complications of GLX is that it uses existing right of way used by MBTA commuter rail trains. So naturally, one of the things to think about is whether the existing tracks could be used more efficiently. Eitan Kensky has been pushing for frequent Diesel Multiple Unit service on the existing tracks for almost a year.


DMU service would be relatively lightweight–a few new platforms (the temporary, wooden kind would be fine at first), a few new trains, and some operational procedure changes. The last point, of course, is a sticky one–it’s hard to trust MBTA to manage anything correctly.

Everything Except New Trains!

As Andy Monat points out, there are plenty of things that could be done to improve non-automobile modes in the Cambridge-Somerville area without building new rail.

Hugely Expanded Bike Infrastructure

Guerrilla bike lane guru Jonathan Fertig thinks a massive buildout of protected cycling infrastructure might attract similar numbers of users and have similar benefits to GLX:

Even More Modernized Commuter Rail Infrastructure

At the price point GLX currently occupies, the same investment could make major progress towards turning the MBTA commuter rail system into something much more useful. Electrification of the Lowell Line and part of the Fitchburg Line (say, out to Waltham) shouldn’t cost more than $160 million combined, plus a few hundred million more for rolling stock–relative peanuts compared to the $3 billion GLX would currently cost. A few infill stations in Somerville and Cambridge, and you’re in business.

There’s also the multi-billion-dollar elephant in the room: the North-South Rail Link. It’s a project that divides Boston-area transit advocates. Many see it as a megaproject that would take away capital investment from more fundamental needs. Others, including me, see it as having the potential to transform the current limited, inefficient, and inequitable commuter rail system into something much more modern and useful to the Boston metro area–but only if it’s accompanied with modernization of the entire commuter rail system.

NSRL is a relevant topic of conversation right now because a new coalition, associated with former governor Michael Dukakis, has just launched a campaign to get the tunnel built, complete with a fancy website.

NSRL plan

The new NSRL service plan, from the coalition website

The irony of NSRL, of course, is that had it been completed as part of the Big Dig project 20 years ago, as originally planned, it might have eliminated the need for GLX entirely. Had NSRL gone forward, and the commuter rail system been turned into a rapid transit system, building GLX on the same ROW might have been entirely redundant. Of course, one could go back even further and say the same of the Red Line extension to Braintree and the Orange Line extension to Oak Grove…but there’s a sad thought.

Please leave more ideas in the comments! There’s lots of room for creativity here. 


6 thoughts on “Green Line Extension Options

  1. I don’t really get why people in large US cities constantly propose DMUs as a solution. It makes me think that they think of these vehicles in the same way transit agencies think of BRT, or (in some cases) of light rail: it’s magic technology that’s not present here and therefore will totes make everything better. The reality in that in a city of Boston’s size, especially in an American regulatory environment, DMUs are the wrong choice. Explanation:

    1. Electrification cost is about the same in large and small cities. But the benefits grow linearly with ridership. In Boston, there are trunk lines with 4 peak tph today, and the ability to support 8-12 peak tph if service is expanded in the future.

    2. DMUs are optimized for small cities, not large ones. For example, some Euro-DMUs are designed to be maintained in bus shops.

    3. US regulations are mildly annoying for EMUs, and deadly for DMUs. Buy America is a death sentence for DMUs; for EMUs, there are factories that make semi-decent equipment today. FRA regs raise DMU procurement costs, and even the waiver process is arduous; but decent FRA-compliant EMUs exist.

    4. The routes in question have very short stop spacing. The high acceleration capabilities of EMUs are of especial use in situations like a GLX substitute. DMUs are useful mainly for lines that call for medium speeds but stops that aren’t too close together; the only example in the area that I can think of is the outer Fitchburg Line.

    • I think people are into DMUs because they’re desperate for *anything* better than the crappy equipment that exists! You’re absolutely right of course that most or all of the MBTA system should be electrified, but that’s pretty clearly not on the table for at least the next for years, so maybe this is the next best thing? Personally, I’d like to see the T buy a few DMUs for the short term while embarking on an electrification project, then shift them to the outer portions of the system that aren’t worth electrifying and to other, smaller operations–Providence-Worcester, Pioneer Valley, Berkshires–once electrification is complete. That way they’re not a total waste.

      • The entire MBTA should be electrified. The issue is that the lines that have enough traffic to warrant it on their own are such a large percentage of the system that it’s worth it to electrify the outer branches just to avoid having to maintain multiple classes of equipment. Potentially, this cascades to tie-ins like Providence-Worcester and (via the New Haven-Springfield connection) Springfield-Greenfield.

        The other issue, which I forgot to mention in #2, is floor height. I know it’s not a huge deal to raise them, but the main products are low- or medium-floor, because they’re designed around 550 mm and 760 mm platforms. This height works if you’re Medford, Oregon, but not if you’re anywhere that might run to major NEC stations. For small orders, I’m apprehensive about raising floor heights, even though generally it’s easy to do so. Ottawa’s O-Train order didn’t even change the language (EN/FR/DE) or the livery (it judged DB’s livery close enough for government work).

      • I believe the largest historical reason for the MBTA and its predecessor the MTA not electrifying was open hostility by the freight railroads which held some veto powers, with the second-largest being the decrepitude of the track and stations (you can’t really conceive of electrifying before doing all the bridge repairs, for instance). Honestly these reasons are mostly gone now; PanAm is in no position to complain about anything, CSX doesn’t control anything anymore, and the major line repairs on most of the lines are being completed with ARRA money. At this point I think it’s just *habit* which is preventing electrification.

  2. Right, the floor height is one of the things that worries me about a Pioneer Valley service. They’re committed to high floors there–a permanent platform is already in place at Holyoke and will soon be at Springfield, with Northampton and Greenfield to follow. I guess building “mini-lows” for Euro-DMUs wouldn’t be the biggest expense, but one of the really promising things about the service as it stands is the potentially incredibly low startup cost. Procuring DMUs with high floors means either a bespoke Euro order or Nippon Sharyo’s FRA-compliants, which as you have vocally pointed out are mediocre vehicles.

  3. Well, if there’s a push to build a Commuter Tunnel again in Boston, I’d say go ahead and electrify the entire network before the first shovel is stuck in the ground. You could achieve many of the improvements and efficiencies you want anyway without having the tunnel in place. Most of Philadelphia’s commuter rail network was electrified before work began on the Commuter Tunnel; the non-electrified portion of the system was a casualty of the project. Electrifying now avoids that possibility and lowers the cost of the tunnel by not needing exhaust systems.

    Funny, though: when I lived in Boston, the lines out of North Station used mostly Budd RDCs, the DMUs of their day. And most of them still ran under their own power.

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