In the 1910s and early 20s, the Boston Elevated Railway Company (BERy, predecessor to the MTA and MBTA) expanded and modified their streetcar subway, making critical additions that transformed it into something recognizable as an early version of the Green Line.
I have written about these changes in the past, but want to briefly summarize the two models that emerged from BERy’s modifications. In both cases, BERy was trying to address the problem of long trolley routes that stretched from the suburbs all the way into downtown, running slowly at street level, usually in mixed traffic, the buses of their day. The original Tremont Street Subway was built with the relatively narrow goal of getting trolleys off of downtown’s congested streets. BERy’s expansions broadened the scope of the streetcar subway significantly.
Kenmore Model
To the west ran some of the oldest surface lines in Greater Boston, the predecessors to today’s B and C Lines, and the now defunct A Line. When the Tremont Street Subway first opened, these trolleys trundled all the way down Boylston St at surface level, entering the subway at the Public Garden Incline between Arlington St and Charles St.
In 1914, the Boylston Street Subway opened, adding a new tunnel that extended through Back Bay with stations at Copley and Massachusetts (now Hynes Convention Center) before emerging at the surface just before Kenmore Square. (A one-stop extension underneath Kenmore Square opened about twenty years later, giving us the station we know today.)
The proto-A, B, and C Lines thereafter entered the portal at Kenmore and ran “express” underground into downtown. Other shorter distance routes continued to operate into the now-relocated Public Garden Incline, but those longer distance routes were given a (comparatively) high speed bypass.
This was BERy’s first attempt to address the needs of suburban surface lines. Under the Kenmore Model, surface routes run like buses before entering a subway in which streetcars run in a dedicated ROW at high speed into downtown, often producing rapid transit-like service as multiple routes layer to form very high frequencies.
The two other legacy streetcar subway networks in the US – San Francisco’s MUNI Metro and Philadelphia’s SEPTA – also utilize the Kenmore Model. The need to travel underground is arguably what spared these systems from “bustitution”, since buses couldn’t adequately run in the subways.
(San Francisco’s Kenmore Model is actually somewhat coincidental: its Market Street Subway, which mimics the Boylston Street Subway, wasn’t built until the late 1960s; instead, the need for streetcars in order to utilize the Twin Peaks Tunnel, to the west, was likely the protective factor in that system.)
The Kenmore Model’s persistence today creates an odd inequity, where residents of Brookline and Allston get to enjoy the convenience of a surface route (with frequent, nearby stops) with a one-seat ride directly into downtown. Residents of neighborhoods much closer to downtown (such as Roxbury) do not enjoy that benefit.
Lechmere Model
When BERy extended their dedicated streetcar ROW out of the subway at Haymarket north to an elevated along Causeway Street and across the Charles River, they initially employed the Kenmore Model at Lechmere as well. Streetcars from Harvard Square, Union Square, Davis Square, and Clarendon Hill ran directly from street-level on to the viaduct and eventually into the subway.
In 1922, BERy constructed a transfer terminal at Lechmere Square. Surface cars from the northwest terminated at what became the bus terminal, while cars coming from the subway looped within the dedicated ROW of the station. This marked a key transformation in BERy’s treatment of its streetcar subway, now treating it as a service that could potentially act as rapid transit.
The Lechmere Model mirrored BERy’s approach at its other rapid transit terminals. At Sullivan, Harvard, Dudley, and Maverick, surface routes that had once run all the way into downtown were truncated, with riders transferring to high-speed rapid transit service. This model remains in use across the system today.
BERy intended to eventually deploy a Lechmere Model approach in the Kenmore area as well. The C would have been truncated to the Kenmore Loop, while the Central Subway itself would’ve been converted similarly to the Blue Line, and extended to a transfer station in Allston to meet truncated versions of the A and B. Obviously, that never happened.
Broader Implications
The Lechmere and Kenmore Models speak to the various factors that govern a transit service’s character:
- The dedicated ROW of a subway or elevated, versus (semi-)mixed traffic-running at surface level
- The close stop spacing of a slower surface line, versus the fast speed of a subway line with fewer stops
- The rider experience of a one-seat ride, versus transferring at a hub
Both models present benefits and drawbacks. The B and C are among the highest ridership surface routes, in favor of the Kenmore Model. After the opening of Lechmere Terminal, BERy was able to run higher-capacity cars in the subway. On the other hand, reliability in the Central Subway is impacted by the amalgamation of multiple surface routes; and transfers exact a penalty on both ridership and rider experience.
Differentiating between the Kenmore and Lechmere Models allows for a more precise analysis of existing services and potential future expansions.