Any proposed public transit infrastructure should be thoroughly vetted to assess the degree to which it will meet the transit needs of the intended market. This is especially true when relevant costs reach the absurd levels of today's highly over priced market for public works.

Boston's proposed Green Line 'light' rail extension is estimated to cost over $1 billion for 4.24 miles of new service. This transit mode was initially dubbed 'light' on account of its lower infrastructure needs, lower speeds, lower capacities, and lower associated costs relative to that of 'heavy' rail transit. It is now clear that 'light' no longer applies to this last element.

2 - Everything On The Table

There is no arguing over the need of better access to Boston's public transit system for the residents of Somerville and Medford; the question to pose is how is this best achieved.   The proposal being advanced, with seemingly no opposition or proposed alternatives, is the Green Line Extension (GLX).  But, operating light rail vehicles in the rail corridor running through Somerville/Medford should not have been so easily leapt upon as the best, or even the easiest, solution merely because a light rail stub sits 'begging' to be extended.

The GLX, as planned, would be an extension of Boston's 'light' rail vehicles into these two densely populated areas, but with the use of heavy rail infrastructure.   The city and MBTA is ready to settle on this as a solution for the heavy lifting function which is needed during the peak commute times, yet experience with the light rail Green Line readily shows it strains in this function.   This method has not been so much chosen by the professionals as it has by the combination of a public crying for more rail service, their perception that the green line is the simplest solution, and a state/local government's willingness two decades ago to promise anything in order to remove impediments to their Big Dig project.

The current MBTA map in Somerville is presented below.  In the far lower portion lies the Red Line running through Cambridge, the Orange Line, in the center, runs between North Station and Malden.  The Green Line also runs from North Station, then ends at its northern terminus of Lechmere Station.

I've also highlighted, in yellow, the tracks used by the Lowell Commuter Line.   These are the tracks the MBTA intends to leave untouched, and will instead add two more tracks beside them in the same rail corridor for the GLX.

The GLX plan is to reroute the Green Line away from Cambridge Street and the current Lechmere Station, to continue on the east side of Highway 28, with a new and elevated Lechmere Station, then to bridge over the Fitchburg Commuter Lines and continue up as a new set of tracks in the Lowell Commuter rail corridor.

On maps like these, the MBTA makes little distinction between its light rail and heavy rail lines.  For most visitors, the distinction makes little difference, but for commuters who must use the system during the peak use hours there is a significant distinction.   Light rail vehicles are not tailored to be heavy load carriers, thus it is important to keep that in mind when spending great quantities of money to propose their use for a transit solution.

Unfortunately, the end of the Green Line at Lechmere Station has become a 'black hole' for decision makers, bypassing a rational analysis of transit needs and ignoring resources which could provide better alternatives.

The goal of any publicly funded rail transit system should be to convert automobile commutes into pubic transit commutes at a price that produces the optimum cost/benefit ratio for the community, and the key to this is providing convenience for the target market.

A fresh and unbiased assessment of the GLX proposal, when viewed in the light of the transit needs targeted and available resources, will reveal three major flaws.  These flaws are fundamental to both the benefits sought and their costs.  In brief, they are:

  • The proposal makes inefficient use of a fully segregated rail corridor, a right-of-way ready made for the speed and capacity levels attained through the use of heavy rail vehicles.  As much of the market, to whom they aim to provide transit service, is in need of the speed which heavy rail can provide, particularly Medford, this strategy will leave this need unmet.
  • The addition of land and tracks to the existing rail corridor for a 'light' rail extension is ill thought.  An appropriate review of resource allocation to needs would reveal the existing tracks are under utilized.  Any proposal to make infrastructure capacity expenditures in this corridor must come only after a thorough search for alternatives to include reallocating resources.  This has not been done. 
  • The convenience of access which 'light' rail could provide to meet the transit needs of residents, particularly in Somerville, is not being provided in this proposal; and worse, the existing resource best positioned to aid in meeting that need, the Green Line stub at Lechmere, is being misappropriated for an inadequate attempt to provide transit needs in an environment structured for and to another market more appropriately served by a heavy rail solution.   

Needs Analysis

Convenience is the pivotal factor potential new riders will weigh when considering a public transit option.   And convenience is not the same for all potential riders.   The farther the commute, the more the speed and capacity of a transit mode will play in that decision making.  As distance of commute shrinks in length the proximity and ease of access to the system becomes a greater factor than speed in the decision.   

With these pivotal factors in mind, it can be seen that providing the appropriate mode of transit to a target market is critical to achieving our goals.   While there is not a hard boundary dividing the two markets, we can well understand that for those who have the option of personal transit, traversing 1/2 mile or greater to access a transit system is less appealing when the final destination is only 3 miles distant than when that destination is 5 miles distant.

Adherence to a private vehicle is not easily overcome.  The appeal of personal space, door to door conveyance, and flexibility of use is a strong competitive force, like a gravitational pull, which must be met with equal or greater force if our aim is to attain the ridership numbers needed to make our expenditures cost effective.  

Therefore providing a mode which is fast, with suitable capacity for peak loads, to those farthest from the city's CBD should be the objective.  This market is differentiated from the commuter rail market by its density of population, which commands more frequent and available service.

For commuters residing closest to the CBD, we must offer the convenience of access.   Thus the strength of light rail is sought for this latter market; that strength being its ability to be closely integrated with highly trafficked pedestrian corridors.  This is explored more on Page 6, 'The Green Line: I Am What I Am'.  

Resource Utilization

The Lowell Commuter Line traverses to and from inner city Boston on a set of double tracks in the corridor now proposed for use in the Green Line extension.  The MBTA's intent is to add a pair of tracks to run along side the existing tracks.

The flaw is that a rational analysis of the larger MBTA system reveals that it is not necessary to increase the trackage in this corridor.   The MBTA is transporting 70,000 weekday commuters from the exurbs and beyond into the CBD using nine rail corridors through the city.  This compares to 325,000 daily riders each way on the MBTA's urban transit lines, using only six trunk lines.

Boston is blessed with numerous rail corridors, but it has yet to realize their potential for transit.  Perhaps this goes back to the shifting of government tax and spend patterns.  If there was no federal funding, the city and state would be forced to be more prudent and efficient in its infrastructure choices.

Active and Inactive Rail Corridors

An efficient use of resources mandates a better allocation of these rail corridors and tracks which transport regional commuters from the outer edge of Boston, through the city, to either North or South Station.

Finding cost effective ways to consolidate some of these lines before they enter the city would free up very valuable land and rail resources in the urban area, a prudent option when seeking to expand the urban transit system.

As is currently planned by the MBTA, doubling the trackage in this rail corridor will require that almost all existing road crossings be modified or completely replaced, at substantial costs of $38,500,000.

An additional cost of doubling the trackage in this corridor is that additional land will need to be required to provide space for stations, which could otherwise be largely accommodated within the current corridor footprint.  As a result, total land acquisitions for this line are expected to cost $44,000,000.

Another expense incurred as a result of the track addition is for retaining walls.  Retaining walls have been itemized at $58,000,000.  And, finally, the actual tracks will cost $12,000,000.

A critical, but yet largely ignored, fault of the MBTA's GLX plan is that it forgoes extending the line to West Medford.  The MBTA has let the zealous, yet understandable, community outrage at the prospect of losing (or having markedly altered) the existing rail bridge over the Mystic Parkway/ River take the fall for why it truncated the line back to the south side of the Mystic River.   

The doubling of tracks, of course, would necessitate a widening of the bridge.  More likely the truth is that the MBTA was quite happy to end the line in Somerville, thus cutting some of the continually escalating costs of the project. 

West Medford will not be the only victim of this shortsighted decision to add tracks instead of reallocating the existing tracks; fast growing areas to the immediate north of it will be long denied rapid rail service.  It can be well expected that an excuse of insufficient funding for additional track extensions northward from College Avenue will last long into the latter part of the 21st century with several generations of residents in those areas choosing automobiles over less frequent and less flexible commuter rail service.