Accessibility-based analysis of infrastructure improvements to the Multimodal Western Corridor in Massachusetts

Abstract

MassDOT is in the planning stages of the Allston I-90 Interchange Improvement Project which, largely due to public participation, could evolve into a multimodal project involving replacing the structurally deficient highway interchange, providing enhanced bike and pedestrian connectivity, building a new West Station, and eventually introducing new passenger rail service using DMU's through Kendall to North Station. With the roadway network operating close to, at, or beyond its practical capacity, these changes could allow for a major modal shift to transit for commuters from the largely residential western suburbs to multiple high growth areas in Boston, including Kendall, Downtown, the Innovation District, and Longwood Medical Center. Growth in these areas is currently occurring in the absence of viable transportation options, rather than because of them, and additional options will need to be provided if future growth in the area is to be sustained. This thesis assumes an optimistic view of continued development by continuing to project high job growth and related transportation demand in the Western Corridor to the year 2030. This includes identifying the mode shift that would be necessary to accommodate this future and designing the service characteristics of the system required to support this shift. These forecasts are considered in the context of other major infrastructure projects and the regional economic impacts they have had. With sufficient investment in new and existing transportation infrastructure in the Western Corridor, including all-electronic tolling on the turnpike, off-ramp reconfiguration, increased frequency on commuter rail, new DMU service on the Grand Junction, and supplementary bus connections throughout the region, it will be possible to sustain high job and residential growth in the Boston area. Without these improvements, particularly those on the transit side, industries and individuals may see reduced accessibility to workers, jobs, and services and may therefore choose to move elsewhere. It is important to factor in these greater regional economic impacts when reviewing the true value of potential improvements to the transportation system.