2 | Cambridge

The Cambridge segment of the Diamond Ring has specific transportation, policy and financing needs. This segment is unique in that it contains MIT and Kendall Square, two major attractors of people and jobs. The area is home to about 27,000 residents and over 56,000 jobs according to 2010 Census data. MIT and Kendall Square continue to influence the development of the area with large amounts of development planned for East Cambridge, Kendall Square, and Central Square. The City of Cambridge has a history of progressive planning and transportation initiatives and generally supports transit expansion, though its ability to make major changes is limited by the State.

Proposed Kendall Square station and development

Proposed Kendall Square station and development

Key Issues

The Cambridge segment of the Diamond Ring, from Lechmere Station to the BU Bridge, faces unique issues including:

  • Rapid and anticipated development
  • Large and broad (spatially) worker flows
  • Need for increased mobility between the Longwood Medical and Academic area (LMA) and MIT
  • Need for increasing connectivity between Lechmere and Kendall

The proposed Diamond Ring offers the opportunity to address some of these key issues creating connectivity and travel-time savings, but also by offering the opportunity for further economic and housing development along the corridor.


In the past 10 years, MIT has developed over 10 million square feet of office, retail, and residential space around Kendall Square. The City of Cambridge estimates that by 2030 there will be an additional 6-9 million square feet of new development in the area. The likely implications of this concentrated development will be the influx of more visitors, workers, and residents of the area.


Kendall Square/MIT actually has a higher transit mode share than the city of Cambridge as a whole at 39.4%, compared to a car mode share of about 45%. The majority of transit trips to Kendall/MIT have origins concentrated within about 2 miles of the area and along the Red Line, and some of the commuter rail lines. For single occupancy vehicles (SOV), the geographic spread of origins is much larger. Also of interest is that internal private vehicle trips within the proposed Diamond Ring corridor only account for 3% of SOV flows.

The Red Line currently operates below its theoretical capacity, but it is prone to unreliability in actual operations, which leads to bunching and overcrowding. Furthermore, overall capacity cannot be improved without improvement of the subway’s signaling system. Given the rapid development described above, we believe that the Red Line cannot accommodate future transit demand in the area and that a major new expansion of transit capacity is needed. The Diamond Ring can supply this capacity and, given the relative flexibility and affordability of bus and BRT systems, can be expanded easily if demand proves to be substantial.

A major challenge for this area will be to limit, and ideally decrease, SOV use in the face of the described development. Unfortunately, it appears that the DR may not divert a large percentage of SOV trips to Kendall, given that the majority of origins are not located in the DR service area. Yet the creation of the DR can possibly spur new location patterns by workers of the area. Younger workers who are more interested in urban amenities and transit access may choose to locate in the region.

A quick analysis of current mode share by age suggests that younger workers are more likely to take transit. Since the act of taking transit is greatly facilitated by locating near transit, it is conceivable that by supplying this new service, employers and workers may relocate to locations along the corridor. Such new development is especially likely in the Inner Belt area of Somerville, or in the air rights developments proposed by the BU Bridge – LMA section of this project.



Alignment and Stations

Right of Way Configurations

Right of Way Configurations

We studied many possible route alternatives in the area and finally selected an alignment that offered the greatest connection to common origin/destinations, efficiency, and connectivity with other major routes.

Our proposed alignment is composed of a mix of bus lanes, busways, mixed traffic and one shared ROW with Buses/Trains.

  • First Avenue: Offers connections to the Galleria Mall and will have bus lanes and peak hour bus priority.
  • Binney Street: Offers connections to current and future businesses in this area, will be a have a dedicated bus lane.
  • Third Street: Due to the minimal width along Third Street and minimal traffic flow, the bus will share the roadway with other vehicle traffic in this segment.
  • Main Street: Offers connections to Kendal Square, the Kendall T station and MIT. The current traffic flow on Main Street is quite low and it is an ideal location for a dedicated transit/pedestrian/bike street that would extend from Broadway to Vassar Street.
  • Grand Junction Railroad: Offers connections to MIT’s Massachusetts Avenue entrance, MIT facilities and Cambridgeport.

The Grand Junction Railroad is an 8.6-mile long rail line that runs from the BU Bridge to Chelsea and is the only reasonable rail link between Boston’s North and South Stations. The segment we have proposed for joint bus/train operations runs from the BU Bridge to Main Street. The right of way is currently owned by the MBTA and the land beneath that right of way is mostly owned by MIT, the City of Cambridge and a handful of private owners. The rail line is used by CSX (its former owner who maintains the right to operate along the line) once per day to connect to the Chelsea Produce market, and the MBTA and Amtrak use it on an as-needed basis for transferring rolling stock between maintenance facilities. On average, there are 3-5 train movements per day, mostly in the evening and night.

Shared bus/train ROW is not very common in the United States or abroad, though some examples do exist. The most notable of these examples is the shared bus/LRT ROW in Seattle’s Downtown Transit Tunnel. Sound Transit has been running joint operations in their tunnel since 2006. Through a variety of safeguards, operational measures and monitoring, the system has proven successful. For the purposes of DR operations, their approach is an excellent model, as it was devised for a system with continuous and regular shared movements. There are two key differences between the operations in Seattle and the
proposed operations along the Grand Junction:

1. The Grand Junction will carry buses, commuter trains, and freight trains
2. The rail operations along the Grand Junction occur infrequently and often at times when the MBTA does not operate

The first key difference is problematic as freight trains especially present a greater potential safety hazard than LRT trains. But the second difference lends support to the feasibility of this approach. Given the limited number of daily operations, the fact that the MBTA owns the ROW (controls usage) and that most operations occur at night, we believe that a system could be devised that allows for safe joint operation of both rail and BRT in the corridor. Such a system would require:

  • Schedule train movements when DR buses are not operating
  • Install signaling system allowing entry only when bus/train is clear of track
  • Install train bypass waiting bays in the corridor to allow for buses to pull off ROW if a train must pass through during DR operations
  • Install surveillance systems and link to MBTA operations center
  • Install and implement redundant safeguards for all of the above

Possible delay caused by train during BRT operations

Possible delay caused by train during BRT operations

We believe this system will offer safe operation along the Grand Junction Railroad. In the event that a train must pass through the corridor during DR operations, buses could pull into bypass bays. Below, we have estimated the total delay that could be experienced. Though not insignificant, given that it would likely occur only occasionally, the impact on operations would be minimal.

Though operation safety and efficiency can be achieved with a shared ROW, under current conditions it is possible this arrangement could prove infeasible due to the introduction of frequent passenger rail service along the alignment, or lack of federal approval based on safety regulations related to required separation from railroad tracks.

The Diamond Ring can be safely and efficiently implemented in this segment, and offers great potential benefits. Aside from the improved linkages between Kendall/MIT, LMA, and Lechmere, the DR creates the potential for transit-oriented development along the western segment in Cambridgeport. Finally, the increase in transit capacity can facilitate the preservation of the current mode share in the area and act to spur new housing location decisions.


Currently, MIT issues 5,886 parking permits for its 4,204 parking spaces. MIT should reduce the parking space available at cheap prices and instead make more commercial parking available at higher prices on the East Campus. The Institute plans to decrease the number of parking spaces to around 3,700 by 2018. Commercial parking can be a good source of small but steady additional revenue. Some parking can be removed to make way for housing for MIT students. The parking lots along the BRT alignment in the west part of campus would be an ideal location graduate student housing and mixed-use TOD.

Commercial parking prices in Cambridge can be raised. Parking surcharges must be charged on private parking garages, which will also encourage people to use public transit. There are many parking lots throughout the Kendall/MIT area, owned in large part by MIT and public agencies. Cambridge could convert some of these lots to much needed affordable housing and small public parks. Memorial Drive parking, currently free, should be charged or the parking must be removed to make way for the waterfront park.

The Cambridge Waterfront

Though we have proposed that the Diamond Ring run through the Grand Junction, we recognize that many in the Cambridge community would like to see a community path with room for cyclists and runners in that same space. If such a path were not feasible in addition to the BRT and rail infrastructure, we believe that well-designed improvements to the waterfront would facilitate local acceptance of the Diamond Ring project.

Over the decades, some proposals have been made to improve the waterfront, though little progress has been made in drastically re-envisioning the priority uses for this invaluable resource. The Historic Parkways Initiative was launched by the Commonwealth in 2001 and has made some improvements along the waterfront, though as the name of the initiative indicates, the waterfront continues as a parkway rather than a park. The 2002 Charles River Basin Master Plan was the result of two years of public participation and lays out options for improving the waterfront. However, the ultimate recommendation for East Cambridge was to make minor improvements rather than convert Cambridge Parkway into a park due to access and parking concerns.

Much like the proposed BRT corridor, planning and implementation of major waterfront improvements would require extensive coordination between various departments of the Commonwealth, as well as Cambridge and MIT. Currently, Memorial Drive is owned and maintained by MassDOT, while the water’s edge under falls under the jurisdiction of the Department of Conservation and Recreation (DCR). If it could, Cambridge would improve access to the waterfront but it does not have the power to do much more than alter zoning regulations and make suggestions to the State.

Our proposals for the Charles River waterfront in segment two break into three stages: flexible uses, minor infrastructure improvements, and major infrastructure alternations.

waterfront loopsIn the first phase, we would like to see Memorial Drive being used by different modes at different times. Currently, DCR closes Memorial Drive to cars between Western Avenue and Mt. Auburn Street on Sundays in the summer. We recommend that this route be extended to Lechmere Canal Park, with further expansion into a loop, either along Cambridge Street or along the waterfront in Boston.

In the second phase, we recommend more significant changes to the allotment of space for non-motorized modes, as well as renovation of the waterfront green space. We propose the removal of two traffic lanes on Memorial Drive, in order to widen the park area along the riverfront. Along the East Cambridge riverfront, we recommend Alternative B presented in the Charles River Basin Master Plan, which would widen the green space from 25 to 45 feet, fully converting Cambridge Parkway into green
space. At this phase, we also propose a full renovation of the waterfront green space, including improved pedestrian and cycling infrastructure, with paved paths, landscaping, seating, and lighting. In order to activate the space, we propose at this stage to introduce restaurants, cafés, and food vendors with tables, at the widest sections of park. These attractions would serve to help draw people to the waterfront during all seasons.

In the final phase of waterfront improvements, MIT would finally be connected directly to the riverfront with a full removal of the road barrier. Funding could come in large part from MIT, an institution with a clear interest in creating an iconic frontage along the water. The alteration would include tunneling Memorial Drive in phases.

Potential TOD parcels, currently MIT parking lots

Potential TOD parcels, currently MIT parking lots


Housing for MIT students, faculty and staff has strained the housing market around MIT, driving up prices. MIT does not provide sufficient affordable housing to its graduate students, who then find less expensive options in the surrounding neighborhoods. As of 2011, 31% graduate students live in non-MIT housing in Cambridge and 28.7% live outside Cambridge.11 The Institute needs to address this issue before it leases out land for commercial interests.

We recommend that MIT dramatically increase its graduate student housing supply, and also provide options for faculty and staff. We see a unique opportunity to create a mixed-use, vibrant hub of development around Ft. Washington Park, which would be served by the Cambridgeport BRT station. Such development would not only provide students with attractive and affordable housing options near campus, but would also increase activity in the area with commercial services and retail.


Financing the proposals beyond the Diamond Ring BRT presents a major challenge and the anchor institution in this segment, MIT, should be looked at as a possible revenue source. MIT may argue that it contributes to the city through the economic activity it generates and that Kendall Square has become one of the most expensive real estate areas due to its proximity to MIT. However, there are several costs that MIT imposes on the City of Cambridge for which the compensation is not sufficient. These include lack of sufficient and affordable housing, gentrification and higher vehicular traffic. Additionally, the DR project will provide many benefits to MIT including connecting its east and west campuses and attracting more development around the west campus.

Most of the funds and revenue sources required to fund the Diamond Ring have been discussed in the finance group report. For this segment, the waterfront development will require a huge amount of funds, as will affordable housing development. One of the major sources of funds is MIT, the anchor institution that will profit the most from the DR and waterfront renovation. Given the degree to which it will benefit, it is logical to lean on MIT to help finance these proposals. Currently, MIT pays only 3% of the amount for its tax exempt property as payment in lieu of taxes ($1.7 million). We propose that an additional 3% can be collected annually from the institution and earmarked for the waterfront development. This would need to be arranged in conjunction with the appropriate State agencies.


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