Infrastructural Constraints Pose Challenges for the Commuter Rail Transformation

Written by: Joanna Gentle, Summer 2026 A Better City Intern

September 16, 2026

This document was prepared by the author as part of a summer internship project. The views, findings, and opinions expressed in this work are those of the author and do not necessarily reflect the official policy or position of A Better City.

 

On June 8, 2026, A Better City held a Roundtable Conversation with senior MBTA leadership to provide an update on its Rail Modernization planning initiative. In that conversation, they shared that the MBTA is planning to transform the Commuter Rail system from a traditional 9-5pm model—serving office workers commuting to Downtown Boston for work—to a Regional Rail model. The work that the MBTA has done so far includes ongoing planning efforts with the development of the Regional Rail Modernization Plan, current undertaking of pivotal capital investment projects, and prioritizing capital spending.

While the MBTA has made much progress towards improving service, transforming the system to the Regional Rail vision will require years of work. These elements include platform accessibility to support fast, high-capacity service, track infrastructure to support frequency and reliability, and power sources to accommodate electrified rail. These constraints will be key factors in prioritizing which Commuter Rail lines to improve first, and how to make key stakeholders aware of the prioritization decision process.

 

Level Platforms

The first element that is needed for a reliable Regional Rail system is accessible and level platforms. According to the MBTA June 2025 Regional Rail Industry Day Presentation, 65% of the 141 stations across the Commuter Rail network are currently only accessible by either mini high-level platforms (62) or inaccessible low-level platforms (30). Transitioning to system-wide high-level platforms aids both accessibility allow a faster and more reliable schedule. The MBTA’s primary challenge for stations and is to prioritize making these platform improvements across the lines under capital constraints to meet the goal of frequent and fast trains.

 

Double Tracking

The second constraint of building the Regional Rail system is the current single-track infrastructure along many segments of both the south and north lines such as the Old Colony Lines, the Haverhill Line, and the Newburyport/Rockport Lines. Adding double tracking—where two tracks run parallel to one another—along the Commuter Rail lines allows for more trains to run in both directions simultaneously. The 2026 TransitMatters and MassINC report Harnessing the Full Potential of Regional Rail with No Regrets Capital Investment Strategy, describes how adding double tracks on the Haverhill line, as one example among many, would allow for greater speed and frequency throughout the entire corridor. While these projects will improve the capacity and reliability of these trains, they are costly and take time to build. This could mean the MBTA should prioritize lines that currently have double tracks, because they can take advantage of already having larger capacity and speed.

 

Electricity Grid

The third element that is essential to the MBTA’s Regional Rail vision is the infrastructure required for pursuing discontinuous electrification. The MBTA plans to use a combination of Battery Electric Multiple Unit (BEMUs) and Overhead Catenary System (OCS) to decarbonize the Commuter Rail system, to both save money and avoid the physical constraints of installing catenary wire across the entire system. Though this more flexible electrification strategy makes decarbonization feasible for the MBTA, the systems still lacks the critical power infrastructure necessary to implement discontinuous electrification as it stands today. In the MBTA’s 2025 Regional Rail Industry Day presentation to prospective bidders for the Spring 2027 Regional Rail operator contract, MBTA planners mention how poor the power grid is in some places, which can present challenges for the battery and catenary electrification. The MBTA’s Regional Rail lines will need new power substations to support both the recharging of BEMUs and provide direct power via overhead electric wires. These critical power needs require substantial capital investments, though the MBTA remains constrained by limited funding availability.

 

Conclusion & Next Steps

These three infrastructural constraints—level boarding capacity, double-tracking infrastructure, and electrification capacity—are a few major examples of the challenges that will factor into the decision-making process of prioritizing the order in which the MBTA transforms current Commuter Rail lines into a fast, frequent, reliable, and accessible Regional Rail service for the future. The MBTA plans to begin discontinuous electrification with the Fairmount Line in 2028. While this line was chosen because of its length and proximity to power infrastructure, there are stakeholders along the 11 other Commuter Rail lines that would like to see similar improvements. The MBTA’s constraints of platform accessibility, track availability, and electricity infrastructure will be factored into future decisions of which lines to prioritize. This makes the prioritization challenging as riders and representatives who wish to see these improvements come to their specific lines might not be aware of the constraints.

While these constraints exist on the MBTAs plan for Regional Rail, one possible solution to addressing riders throughout this process is to make the public aware of how these constraints impact the MBTAs decision making process. If the public understands the constraints of their specific line whether it be energy infrastructure or level platforms, they might be more inclined to understand when their line could see enhanced service. This awareness will keep the public engaged and celebrate the work that the MBTA is doing to improve rail service across the system.

 

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