Boston’s subway is straining with new growth. It is time to rethink America’s oldest subway for the 21st Century.

Over the last 15 years the South Boston Seaport district, once an ocean of parking for south shore commuters, has finally began to develop and is now experiencing growing pains. New hotels, offices, and soon residences have been built at a breakneck pace. In the 1990s, during the Big Dig, planners saw the potential of the empty land sitting next to downtown Boston and South Station. A new transit tunnel was proposed connecting the area to South Station which was designed to uses electric buses that would continue on to Logan Airport via the new Ted Williams Tunnel. The Silver Line was to be one of the first Bus Rapid Transit (BRT) lines in the country and the Feds wanted to use it as a showpiece. Seeing this the MBTA realized that their only source of new funding would be for BRT lines and soon they expanded their vision to include the long delayed Washington St Orange Line replacement with a scheme to connect the Seaport tunnel with a new service through downtown and south to Dudley Sq. The Washington St service, all above ground, opened in 2001 and the tunnel opened a year later. But the connection, a tunnel from Washington St to South Station, was doomed to failure. The project involved destroying the existing, but abandoned, Tremont St Tunnel (part of the original subway) and building a giant underground loop below Boston Common because the turns in the tunnel would be too tight for buses. The cost far outweighed the benefit as there was very little demand from Roxbury to the Seaport. The Feds finally ended support for the tunnel and the MBTA gave up their BRT crusade.

As the Seaport grew it became clear that the Silver Line wouldn’t be enough. The Silver Line runs in a 1 mile tunnel from South Station to D St where it crosses D St and enters into a private road known as Silver Line Way. The grade crossing was a way to cut costs in the original design but has caused traffic issues as the Seaport builds out. The buses must then retrace their route on surface streets to access the Ted Williams Tunnel due to the Mass State Troopers refusal to allow the buses to use their private highway on ramp. The use of that ramp would cut an extra mile off the trip. On the return journey there is no closer off ramp to use so buses must exit at B St and pass in front of the entrance of the World Trade Center Station before going back to Silver Line Way, only to enter the tunnel to WTC again. This roundabout route was never well thought out but didn’t matter all that much when there wasn’t much traffic on the streets.

The streets themselves are another matter. As it was left up to the developers to create their own side streets only the arterials were designed, and in typical fashion they were designed as wide suburban arteries with four lanes plus a turning lane and parking lanes on each side. Seaport Blvd even features a wide median but this has always been a blank concrete slab rather than a planted tree lined feature. Bike lanes were installed but due to the prebuilt sidewalk bulges they are on the street side within the door lane. The Seaport is quickly turning into a dense urban neighborhood but its streets are stuck in the suburbs. Ideas are starting to be floated about what to do with the Seaport but they tend to be, literally some times, pie in the sky such as a gondola system from South Station. Ironically, if the city was to install bus lanes along Seaport Blvd and Summer St the Silver Line would have a quicker journey from the Airport to South Station. The tunnel, therefor, should be used for the Green Line.

Red-Blue Connection & the Essex St Connector

The Boston subway was designed with four major downtown transfer points: Park St, Government Center, State, and Downtown Crossing. As Boston had a strong hub-spoke transportation network this made sense and has worked for the last century. But as areas away from downtown begin to develop, such as the Seaport and Kendall Sq which are both along the Red Line, this system is no longer balanced and the transfer stations are beginning to strain under the crowds. Accessing the Silver Line at South Station often requires a transfer at Park St (Green Line) or Downtown Crossing (Orange Line) and these are so overcrowded that the platforms become dangerous. The crowding delays trains as riders try to squeeze into already packed cars. Planners have even toyed with the idea of combining the two stations with one giant platform but the narrow Winter St under which the Red Line runs would not have space for such a station and it’s questionable how helpful this would even be.

The solution is to create new transit nodes which can take transfer pressure away from the core. In the process this will open up new radial lines that will serve the two new business districts. The first node will be to extend the Blue Line west along Cambridge St to Charles/MGH. This extension was part of the original settlement between the Commonwealth and Conservation Law Foundation when the Foundation sued over emissions mitigation during the Big Dig. Under the agreement the Commonwealth agreed to build the Green Line extension to Medford, the Red-Blue connection, and restore the Arborway streetcar. After the Big Dig ended the Commonwealth went to court to ask that it only need to build one transit extension and the Green Line to Medford was chosen over the Blue. As Kendall Sq continues to grow the Blue Line extension will help by letting riders from the north and northeast reach the Red Line and avoid Park St.

The second solution is to build on the bones of the dead Silver Line Phase III with a much simpler tunnel from the Green Line between Arlington and Boylston St to South Station. When this section of the Green Line was built there were provisions built into the walls to allow for a branch to Post Office Sq but nothing more was ever built. Also along this section are the remains of two separate portals which once served streetcars from the west before the subway was extended. This extra space within the tunnels is a perfect location for a junction to be built with two tracks descending as they head east. This new tunnel must dive deep to pass beneath the existing abandoned Tremont St tunnels. Boylston St between Tremont and Washington is only 40 feet wide so to fit with a new station the tunnels must be bi-level with the Seaport bound track on the upper level and the Kenmore bound track on the lower. A new mezzanine will connect the Green Line at Boylston and Orange Line at Chinatown allowing riders to once again avoid the Park-Downtown Crossing mess.

As the Silver Line was designed with Phase III in mind, there is space along Essex St above the Central Artery tunnels for the transitway and at South Station there are bellmouths in the walls of the Silver Line for this connection. The Silver Line tunnel through the Seaport was also built with light rail conversion in mind so all that is needed is for tracks to be added to the tunnels (and possibly a second set of power wires in the ceilings). While threading a new tunnel and station along such a narrow street in the congested heart of Boston is no simple task it is the only difficult section of the project.

Once connected a branch of the Green Line will be rerouted to the Seaport. At Silver Line Way is a bus loop which can be converted to a trolley loop with space for layup tracks. As the new extension only adds 1.5 miles to the Green Line network the trolleys will still have access to existing maintenance facilities so no new yard is needed in the Seaport. Creating a one seat ride between the Seaport and Back Bay has other advantages as well. The Seaport has a number of new hotels to support the giant convention center but these are also useful for traveling business people who need to reach the Financial District and Back Bay. Tourists will have a one seat ride to Fenway Park or for parents whose children go to BU or Northeastern they can stay in the Seaport and not have a complicated multi-line ride. Commuters from the south will no longer have to change at Park St but instead can change at South Station.

The Silver Line was built to allow both buses and light rail to run together but this may have some operational complications. Because the buses don’t run along a fixed guide way they are limited to 10-15mph. Light rail can go much faster while on tracks so mixing the two will cause delays. What is then needed, should this prove unworkable, is a new network of street level bus lanes throughout the Seaport. Such lanes would vastly improve Silver Line running time as the buses no longer have to double back and can run straight from the Ted Williams Tunnel to South Station with stops in between.

A Greater Green Line Network

The Essex St Connector is the most vital part of fixing the downtown congestion but it is far from the only issue facing the Green Line. As the first subway in the US the Green Line is really a collection of different transit ideas all built at different times. Originally conceived as a way to remove streetcar congestion on the surface streets the Green Line operated dozens of different routes, some which terminated at Park, others at Scollay Sq (now Government Center), and finally some to North Station. As rapid transit began to change how people commuted fewer were using streetcars and more were riding the heavy rail lines which opened up the suburbs to faster transit. The dozens of streetcar routes were eventually whittled down to four but when the new Riverside Branch opened it proved so popular that trains had to be taken off streetcar routes, thus dooming the A Branch.

Due to the mixing of service, streetcar and light rail, and the multiple bottlenecks as new branches were added, the Green Line is running below peak efficiency. At Copley Sq E trains must pass in front of all others as it changes to Huntington Ave, at Park St 4 tracks merge into 2, at Government Center terminating trains must loop back but have no extra track on which to layup. The B Branch has stations so close together that it is often better to walk. And on all sections that run along the streets trains must wait at traffic lights like any other vehicle. So while the Essex St Connector is a short term solution, long term the Green Line needs much more work.

The first step is creating a separate system for streetcars (B/C/E) and light rail (D). While most people often use these two terms interchangeably there is a difference. Streetcars are often lighter than light rail cars and can run in mixed traffic or along medians but adhere to traffic signals. Light rail runs along a dedicated right-of-way and has no (or as few as possible) grade crossings. Trains can be longer and faster. Many times both systems work together as light rail trains can run on dedicated ROWs until they reach downtown and then operate on city streets.

When the Huntington Ave Subway was built in the late 1930s it was originally designed to have a second section along Stuart St to Tremont St where it was to connect with the Tremont St Subway using the existing flying junction south of Boylston St station. This would allow trains to not have to pass in front of one another and Huntington Ave trains could use the separate outer tracks to Park St, thus eliminating any congestion with other lines. Due to the limited WPA funds a simpler connection was made at Copley Sq which forced trains to cross at grade. Additionally plans had been proposed as far back as the 1920s to extend as subway down Huntington Ave to Mission Hill and on to Brookline.

Building a new Stuart St Subway from Tremont to Huntington Ave and extending Huntington Ave to Brookline would create a second trunk through Back Bay and allow both D and E trains to have separate access to the outer tracks at Park St (the original tunnel would be modified so that any future service south to Dudley Sq could be added without conflict). This doubles capacity on the B and C Branches and as it is the D and E which are to be extended to Medford and Union Sq, respectively, then B trains can be terminated at Park St while C train can be rerouted to the Seaport. The street running section of Huntington Ave will be replaced with a tunnel to Brookline Village where the D will be rerouted through a new tunnel bellow Route 9. This new tunnel will be part of a larger complex which comprises of a new loop for shuttle trains to keep servicing Longwood and Fenway Stations, looping back at Kenmore Sq. The Brookline loop will also have switches in place to allow through running to Kenmore during Red Sox games. While complex, no land would need to be taken for the Brookline loop as the portals would be built along the existing tracks and the new tunnel would run under the Boylston St Park to reach Rt 9. The loop itself would run around the large 10 Brookline Pl office building and along Pearl St. A bi-level station would allow for cross platform transfers to the shuttle. West of the station would be a layup track for short turning rush hour trains. While complex this layout allows for maximum operational flexibility.

Having two branches along the Riverside Line means that one can be used to replace the Needham commuter rail line with light rail. As outlined in the recent Transit Matters Regional Rail report the Needham Line will eventually need to be replaced with rapid transit due to capacity constraints along the Northeast Corridor. The Green Line can add service through Upper Falls and replace the existing service to Needham Junction while the Orange Line will be extended to West Roxbury and possibly on to Dedham (more on this later). A new flying junction will be built at Newton Highlands with infill stations in Upper Falls and Gould St-Route 128. As this section of the Riverside Line has few stations the trip will only add a few minutes to the commuter rail journey and this will be offset by much higher frequency.

A New A Train

The new capacity afforded by the Huntington Ave extensions will allow for more B and C train service. It will also allow for the restoration of the A Branch which was discontinued in 1969. Today it is not the suburbs of Brighton and Newton which are growing but the new neighborhoods in Allston which beckon. The existing I-90 Mass Pike interchange which takes up a good chunk of Allston is set to be removed and the land redeveloped. Harvard has been redeveloping much of Allston as it expands south from Cambridge and this provides a once-in—a-lifetime opportunity to create a new transit link. Because of the odd angles of the Allston street grid and the legacy of both rail yards and highway ramps cutting off northern Allston from Commonwealth Ave it is time consuming to go from Harvard to Brookline and on to Longwood (where the Harvard Medical School was built). The 66 bus does this serpentine run daily and one of the most popular routes in the system. With the addition of the proposed West Station in the soon to be developed neighborhood it is not hard to look at the current conditions of the Seaport and see the city making the same missteps as they did before.

The new A Branch could help by connecting the new neighborhood with Harvard Sq and Comm Ave. This will be more complex than it seems at first but if built while the land is already being redeveloped it will end up costing far less to build now than once the land is full. There are two options for the alignment: the first would have the A Branch running along Comm Ave to Pleasant St where between Pleasant and Babcock Sts a new portal would be built in the middle of the median. Doing this would require taking a lane of traffic on each side of Comm Ave which would be offset by removing the parking lanes for this block. The new tunnel would turn north under Babcock and would dive below BU, the commuter rail tracks and the relocated Mass Pike. The station would also act as a pedestrian connection between the new neighborhood and BU as BU has refused to allow any new streets be built through its land. The second alignment would involve extending the tunnel from Kenmore west to Armory St with a new, single Boston University East station along the way. Around the BU Bridge the tunnel would split with a flying junction so that A trains would run under the Mass Pike and ascend along the Grand Junction tracks, following the newly aligned Mass Pike at grade to a new station parallel to West Station. The B Branch would continue west a few hundred feet before coming to the surface around Armory St. The first alignment would continue north through land which is to be redeveloped so that a shallow tench or short tunnels would suffice but the second alignment would require building a new tunnel from West Station along North Harvard St which would cause much more disruption.

Stations along the line would be at West Station, Cambridge Ave, Western Ave and North Harvard St at the Harvard Business School. From North Harvard St the line must dive below the Charles River to continue to Harvard Sq. The line will use an abandoned section of Red Line tunnel to terminate within Harvard Sq. The Red Line once terminated at Harvard and there was a maintenance yard just south of the square with a three track tunnel connecting to the station. When the Red Line was extended to Alewife this yard was sold to Harvard which built their Kennedy School of Government in its place. The tunnels, however, still remain as does a ROW through the two buildings to Brattle St. The new A Branch would enter these tunnels and where one of the tracks would be replaced by a platform. The exiting tunnels are located next to the Harvard Station mezzanine meaning that the side walls could be easily opened up for transfers to the Red Line and bus lines.

Building on my critique of the Grand Junction as rapid transit this new A Branch would better serve the Cambridge Boston-West market. One of my pet peeves about new rapid transit lines is that they often exist by themselves and not part of a greater network. Rapid transit on Grand Junction is basically just a shuttle between Allston and North Station but an A Branch would feed into the existing network and actually improve on popular routes. While not as detailed as the old Urban Ring proposal the A Branch would connect Harvard with Longwood via Kenmore Sq. The new branch would have a built in ridership and riders coming from the northwest Red Line or west via bus routes would could use the new branch to access Back Bay without needing to go downtown. Imagine not having to ride all the way downtown just to turn around and head back out.

Orange Line

Though most of this post is focused on how a reconfigured Green Line would revolutionize travel around Boston there is one additional project that needs to be added. When the E Branch replaces the Needham commuter rail line this will cut off the stations in Roslindale and West Roxbury. Replacing the Needham Line is an all-or-nothing proposition so by extending the E we must also extend the Orange Line. There are other benefits to such an extension. Right now between Roslindale and Forest Hills marches an army of buses every rush hour. Most of these riders are headed to the Orange Line and not the commuter rail so extending the Orange Line means taking hundreds of buses off the streets. The Orange Line is also maxed out on service due in part to the limited number of trains. Wellington is the only train yard and a second one will be needed to boost service. To avoid redeveloping wetlands along the route there seems only one suitable location which is to redevelop the strip mall along Gardner St west of the VFW Parkway. I might even endorse a new terminal station here but that would only encourage development along the Charles River wetlands and this should be avoided. A second possible location would be just north of the Dedham Mall but this would require tunneling under a residential neighborhood as the former ROW to Dedham has since been built over. If the Dedham location should prove worthwhile then a new terminal at the Dedham Mall would be included.

Lest the reader get lost in this grand vision keep in mind that the most important section, the Essex St Connector, can be done first and the rest is a speculation on what would help the network in the future. Fixing the crush downtown is priority number one so creating new transfer points at South Station and with the Blue Line at Charles/MGH is what the MBTA needs to be studying today. The Seaport will choke on growth if transit is not addressed and congestion downtown is causing cascading delays throughout the system.