This page wrote about how extending the E Line just a few blocks would have benefits which would compound across the system. It’s not the only portion of the T where this would be the case. While long-range extensions of the subway system are probably suboptimal from a cost-benefit analysis (and would be better served by Regional Rail improvements), it’s important to think strategically about what improvements could be made. Sky Rose’s Red Line conversion of the Mattapan Line is one such idea, the E to Hyde Square another, and the eventual rapid transit conversion of the Needham Line (the topic of a different post) a third.

Here’s another. In this case, as in the others mentioned, the extension of the line in question not only improves service for the short extension, but helps build in redundancy and resilience in to the whole line to improve service across the board. Building a new terminal also helps, allowing the T to better manage headways across the line, rather than relying on the current substandard terminal at Oak Grove.

Why run past Oak Grove?

When the new Orange Line routes—built as the Southwest Corridor to Forest Hills in 1987 and Haymarket-North to Oak Grove route in 1975—were first proposed, the current termini were not planned to be the ends of the line. On the south end, the route was proposed to extend south to West Roxbury and then to Dedham (the right-of-way to Dedham has been sold off and developed, so this is no longer feasible), and on the north side, it was proposed to extend along the Western Route (the Haverhill Line) to 128 and Reading.

Neither of these came to fruition. The extension to West Roxbury would require a full-scale conversion of the Needham Line. It can’t be done in sections (with the possible extension of a segment to Roslindale), but would require severing the Needham Line entirely, extending the Green Line from Newton Highlands to Needham, and building the Orange Line out to West Roxbury or Needham. The right-of-way could easily accommodate this, but it would require entirely new stations and at least two new bridges built on existing abutments. It’s a worthy, logical project (especially since it would take some of the pressure off of South Station, reducing the need to build the $5 billion South Station Expansion project) and would dramatically improve service to the area, but it would be relatively expensive and politically difficult.

The northern extension, to Reading, would be harder still. While the Needham Line is grade separated to Needham Junction, the Western Route has more than a dozen grade crossings between Oak Grove and Reading, including several in Melrose starting a mile to the north. It would require trains with pantographs and full crossing rebuilding, or full grade separation, and service levels which would exacerbate congestion in the corridor at the many grade crossings. Extending the Orange Line would require running all commuter and freight rail service across the Wildcat Branch to the Lowell Line, putting more strain on that main line. It would be technically feasible, but practically and financially (and probably politically), it is not about to happen.

The first mile going north is a different story. Oak Grove is not particularly well-sited for a terminal station, which work best when they serve dense nodes of ridership generation. It has park-and-ride lot which is accessible by local streets—but not from any highway—and mostly serves a local population. While there is some good transit-oriented development near the station, beyond that is parkland: to the east is Pine Banks reservation, and to the west, the Middlesex Fells. Much of the ridership at Oak Grove comes from Melrose, a relatively-dense town with a border just north of the station, where many residents have to choose between walking to the infrequent-and-costly Commuter Rail, playing roulette with the bus schedule, or driving to Oak Grove. Many choose the latter, and with the small size of the parking lot, it is frequently full before 8 a.m.

If you calculate a catchment area for Oak Grove based on Census block data, there are about 5000 people who live within half a mile of the station (and don’t also live within half a mile of Malden Center, with the assumption that passengers closer to Malden would walk there rather than Oak Grove). Oak Grove is situated in between Pine Banks park to the east and the Middlesex Fells to the west; while parks are beneficial urban amenities, they do little to attract ridership to the Orange Line. One mile north, however, there are many more people. Instead of Pine Banks and the Fells, there’s a mixture of single-family and multi-family housing and a population density of more than 10,000 per square mile, one of the densest areas in the Boston suburbs. (It’s also one of the suburbs which has at least been talking about increasing density near transit stations, which might be one of the most important single goals for the housing-starved region.) So, if you draw the same circle around Wyoming Hill that you did around Oak Grove, 9000 people are within an easy walk.

How a new terminal can improve high-frequency service

In addition, since Oak Grove was never designed to act as a terminal, it doesn’t work particularly well as a terminal. This is similar to the issues this page has previously discussed at Alewife. A Wyoming Hill terminal, especially one built with three tracks, would allow more resilient operations. The Oak Grove terminal is currently dependent on a single crossover to the south of the terminal, and can become congested at peak hours, impacting the rest of the line; providing an extension to Wyoming Hill could provide a terminal with more capacity and a better operational design. Tail tracks extend past the station, but are unused and overgrown before terminating about 3500 feet south of Wyoming Avenue. The right-of-way is wide enough for rapid transit and Commuter Rail service to coexist (it’s at least as wide as the right-of-way to the south in Malden) although to extend the Orange Line, the Haverhill track would have to be shifted east (with the potential benefit of eliminating what is now a 45 mph speed restriction on a reverse curve) and the double track switch may have to be relocated, which would have minor impact on operations. (A fully two-track Western Route would require major bridge work and earthwork between Oak Grove and Malden.)

It would also allow the Orange Line to operate with a double set of terminals on the north end, where the line ends with neither a loop nor a yard. There are few rail lines in the US which have three-minute headways and manage to turn trains at a station like Oak Grove (the Orange Line isn’t currently programmed for such headways, but if it one day ran from Oak Grove to West Roxbury, it might need them). Three minute headways depend on the ability to minimize dwell times at stations, and the ability to turn trains at the end of the line.

In the US, New York and Chicago have several lines with three minute headways, but few (if any) of these operate these headways to a stub-ended terminal at the end of the line. In New York, except for two lines which terminate in Manhattan (the L and the 7), this is achieved through branching. For instance, the 4 and 5 trains on the Upper East Side in New York run 28 trains per hour (a 2:09 headway) in Manhattan, but the trains originate at three terminals on the north end (Nereid Av, Eastchester/Dyre Av and Woodlawn) and two on the south (Crown Heights and Flatbush, with some additional service from other locations). In other cases, interlined lines do not run all trains to the end of the line, but have some turn back shy of the terminal (the 6, for example) at peak hour. (Alon has written a lot about branching in NYC; it used to have even more.)

The CTA Blue Line schedule showing how many rush-hour trips begin or end their runs at mid-line terminals to provide more service on the core of the system.

In Chicago, several single lines (Red, Blue, Brown) run three minute headways (the Blue Line runs 2:40 headways at peak hour) but all terminate at yards, loops, or more-than-two-track terminals (in the case of the Brown Line, where the three-track terminal at Kimball has a capacity of 21 trains per hour). The Blue Line, which is operating 23 trains per hour, doesn’t operate all trains to end-of-line terminals, but basically runs two services overlaid at rush hour: O’Hare to UIC-Halsted and Rosemont to Forest Park. If the Orange Line (in Boston) one day ran from West Roxbury (or Needham) to Wyoming Hill, the most frequent service might only run from Oak Grove (or even Wellington, which with its third track is well-suited for a short-turn terminal) to Forest Hills. So at peak hour, there would be a train every six minutes between Oak Grove and Westie/Needham, and every three minutes from Wellington to Forest Hills, but no terminal would have to turn a train more frequently than every six minutes (which wouldn’t require a three-track terminal at Wyoming Hill).

Track layout at Wyoming. Commuter Rail tracks shifted east over existing platform. Orange Line shown with a two track terminal, with an optional third track and second platform shown to the west.

How extending the Orange Line improves service beyond the Orange Line

Beyond benefitting the Orange Line, this plan would improve service for Commuter Rail riders. Today, most Haverhill line trains make all local stops, including three in Melrose. The stretch from Cedar Park to Wyoming Hill is just half a mile, which doesn’t give any time to accelerate, so it adds several minutes of travel time. A full-speed trip from Cedar Park to Malden this would result in a faster trip for most commuters on the Haverhill Line. (It’s also possible that the two stations could be consolidated with a new station near the high school—with the assumption that many current Cedar Park customers would walk to Wyoming Hill for the more-frequent Orange Line—although this would require further study.)

Having a station a closer walk to many in Melrose would also benefit parking availability at Oak Grove. Consensus is that the Oak Grove lot is full by 7:30 a.m., if not earlier, despite charging $9 per day for parking. Shifting some parkers to walkers by proving a closer Orange Line option would provide more availability at Oak Grove, meaning that some later commuters who today drive to Wellington (or maybe all the way in to the city) would be able to leave their car earlier and get on the train, reducing congestion.

Building this extension wouldn’t be perfectly simple, but it could be done within the existing right-of-way and a portion of an existing parking lot at Wyoming Hill. The right-of-way is 80 feet wide, with at least 65 feet usable (given nearby wetlands), wide enough for two 31-foot rights-of-way. Power is already provided from a substation north of Oak Grove, and another would not likely be required since it is only 0.8 miles from the substation to Wyoming Avenue. At Wyoming Hill, some of the parking lot would be eliminated to build a terminal, and reaccommodating this parking would have to be studied. However, no physical buildings would be impacted, and a two-track station would impact only a small portion of the parking lot.

This extension would not be possible today, because the number of cars serving the Orange Line is stretched too thin as it is. With the new fleet in testing and promised to come online later this year or early next, however, this extra service could be provided, without stretching headways and pushing the line further over capacity. (New signals, in the long run, will also help increase capacity.) Beyond Wyoming Avenue, the cost to extend the Orange Line likely exceeds the benefits. But between Oak Grove and Wyoming Hill, the benefits are high for operations, existing riders, new riders, and parallel Commuter Rail riders, and the costs relatively low.