Boston Green Line Extension (GLX), Massachusetts – Railway Technology

This article explores the comprehensive engineering and logistical challenges overcome during the construction of the Boston Green Line Extension (GLX), a significant expansion of the Massachusetts Bay Transportation Authority’s (MBTA) light rail system. The project, a testament to modern railway infrastructure development, involved not only the extension of the Green Line but also the construction of new stations, a vehicle maintenance and storage facility (VMSF), and significant upgrades to existing infrastructure. The aims of this analysis are to detail the project’s phases, highlight the technological advancements incorporated, examine the complexities of managing such a large-scale undertaking, and evaluate its overall impact on the region’s transportation network. We will delve into the project’s planning, execution, and the resulting improvements in passenger experience and regional connectivity, offering valuable insights into large-scale urban transit projects.

Project Overview and Phasing

The GLX project, a joint venture between the MBTA and the Massachusetts Department of Transportation (MassDOT), significantly expands the Green Line light rail (LRT) system. The project encompasses the construction of seven new stations: Lechmere (relocated), Union Square, Washington Street, Gilman Square, Lowell Street, Ball Square, and College Avenue. In addition to these new stations, the project included the construction of a new VMSF, extensive bridge work, and the relocation of existing commuter rail tracks. The project was executed in four phases, each with distinct objectives and timelines. Phase 1 (early 2013 – March 2015) focused on initial infrastructure improvements. Phases 2 and 2A extended the line to Union Square and Washington Street. Phase 3 involved the construction of the VMSF. Finally, Phase 4 (2015-early 2020) completed the line’s extension to College Avenue. This phased approach allowed for controlled execution, managing risks and resources effectively.

Technological Advancements and Infrastructure Upgrades

The GLX project incorporated several advanced technologies and infrastructure improvements. All seven stations feature modern amenities such as ticket vending machines (TVMs), fare gates, accessibility features (TDD, push-button intercoms), and advanced information displays (VMS and PA systems). The project involved the construction of 1.2 miles (1.93 km) of viaducts and bridges and approximately 25,000 feet of retaining and noise retention walls. The new rolling stock consists of 24 Type 9 light rail vehicles from CAF USA, featuring low-floor design for accessibility, advanced climate control, improved signage, and enhanced safety features, including crash energy management (CEM) and onboard video recording.

Project Management and Collaboration

The GLX project exemplifies successful collaborative project management. The MBTA and MassDOT partnered effectively, and the project involved numerous contractors and subcontractors. Key players included the general contractor, WSK (a joint venture of J.F. White Contracting, Skanska USA Civil Northeast, and Kiewit Infrastructure), subconsultant GAI Consultants, Barletta Heavy Division (Phase 1 construction), and the Gilbane Building Company/HDR Engineering joint venture (JV) (Phase 1 project management and design). The effective coordination between various entities and subcontractors was crucial to the project’s success. Effective project management ensured the timely completion of various phases and mitigated potential conflicts.

Project Outcomes and Conclusion

The GLX project represents a significant enhancement to Boston’s public transportation system. The extended Green Line provides improved connectivity between Cambridge, Somerville, and Medford, reducing commute times and offering residents access to better public transport options. The project created numerous jobs during its construction phases and delivered significant environmental benefits by promoting public transportation use. The enhanced accessibility features at all new stations promote inclusivity for people with disabilities. The new vehicles and improved infrastructure contribute to a safer, more comfortable, and efficient passenger experience. The project’s success highlights the importance of careful planning, effective collaboration, and the incorporation of modern technologies in delivering large-scale railway projects. The successful completion of the GLX demonstrates the value of sustained investment in public transit, its capacity to stimulate economic growth, and its positive impact on the urban environment.

Company Information:

• Massachusetts Bay Transportation Authority (MBTA): The primary public transportation agency in the Greater Boston area.
• Massachusetts Department of Transportation (MassDOT): The state agency responsible for transportation infrastructure.
• CAF USA: A supplier of light rail vehicles.
• WSK (J.F. White Contracting, Skanska USA Civil Northeast, and Kiewit Infrastructure): The general contractor for the project.
• GAI Consultants: Subconsultant to WSK.
• Barletta Heavy Division: Contractor for Phase 1.
• Gilbane Building Company/HDR Engineering: Joint venture for Phase 1 project management and design.
• AECOM Technical Services and HNTB Corporation: Joint venture for final design engineering services.