Chapter 3 I-90 Allston Interchange Project DEIR

1 3 Alternatives Analysis Summary of Preferred Alternative Concept Development The Preferred Alternative Urban Interchange 3K was developed sequentially, beginning ENF 3 Chapter with the results of the Alternatives Analysis described in Attachment 9 of the DEIR FEIR Environmental Notification Form (ENF). The ENF described the then-preferred Urban (PUBLISHED OCTOBER 2014) Interchange 3J Series concept, which included three components: the reconstruction and realignment of the I-90 interchange, the reconstruction of a rail layover facility at Beacon Park Yard (BPY), and the construction of a new commuter rail station, designated as West Station. The features of the ENF 3J Series Preferred Alternative Group 1 & 2 | Suburban Style Interchange are illustrated in Figure 3-1 (provided at the end of the chapter). Secretary’s After the publication of the ENF, the Massachusetts Department of Transportation Dismissed from further study: Certificate MassDOT (MassDOT) continued refining and enhancing the Project concept. The Secretary’s – on the ENF Occupied a large amount of space modifies Task Force requests Certificate on the ENF provided guidance and suggestions to improve the 3J Series –Did not fit the urban context 3J Series Member MassDOT concept. Project stakeholder input from the Task Force, ongoing public participation, to address Alternative –Did not accommodate future land development to evaluate inter-agency collaboration, and coordination with Harvard University and abutters Secretary’s Concepts –Did not accommodate multi-modal connections a modified provided additional approaches and ideas. comments 3J Alternative Taking all of this input into consideration, MassDOT developed the current 3K Preferred in DEIR Alternative with three variations for the Throat Area. These variations are illustrated in Figures 3-2, 3-3 and 3-4. The adjacent flowchart, entitled “Summary of Preferred Group 3A through 3I Alternative Concept Development,” graphically represents the steps taken to determine the 3K Preferred Alternative. Dismissed from further study: –Inade quate traffic operations and safety –Limit ed accommodation for West Station, multi- modal connections and future development Final EIR to select Preferred Throat Area MassDOT 3K Series Variation and At-Grade developed as 3K-4 identified further enhance Concept modifications as optimal Preferred 3J Series Feasibility to 3J Series Alternative Study concept in – Improves traffic operations and safety response to DEIR – Accommodates multi-modal connections and comments future development West Station I-90 Urban Interchange 3K Preferred Alternative –A dded to enhance transit opportunities MassDOT I-90 Urban modifies 3K-4 Interchange in response 3K-4 renamed 3K Preferred to BPDA as 3K-HV, Alternative with Placemaking 3K-AMP and three Throat South Station Expansion Projects Study, Task 3K-ABC Area Variations Force and (3K-HV, 3K-AMP –R equires some rail layover and maintenance public input and 3K-ABC) facilities in Beacon Park Yard Alternatives Analysis Alternatives 2 This chapter describes the development and evaluation of alternatives considered for 3.1.1 Guiding Criteria for the Development of the Preferred • Minimize wetlands impacts each Project component: the highway interchange, the rail layover facilities and West Alternative and Throat Area Variations • Minimize noise impacts Station. As the elements are interconnected, each alternative has an influence on the Chapter 3 Chapter • Maximize/create parks and open space This section summarizes the guiding criteria used to develop the I-90 Urban design of the other transportation infrastructure within the Project Area. MassDOT • Manage contaminated soils Interchange 3K Preferred Alternative and the three Throat Area Variations. The evaluated the alternatives according to their ability to meet the Project Purpose and • Improve air quality Need, as well as guiding criteria developed in collaboration with Project stakeholders. development of the basic Preferred Alternative is documented in the October 2014 ENF, which examined a series of alternatives including several suburban- • Accommodate future land use development and community cohesion This chapter also provides documentation of the guiding criteria used to develop and type interchanges and a separate series of urban-type interchanges. Additionally, • Control construction-phase impacts including cost, schedule and lifecycle evaluate the I-90 Urban Interchange 3K Preferred Alternative and the Throat Area a set of less traditional solutions was considered including: cost/maintenance Variations. The Task Force, which met through February 2017, provided continual input on the refinement of the Preferred Alternative and the variations presented • Depressing I-90 below existing grade levels Application of the guiding and screening criteria resulted in the preferred I-90 Urban herein (see the Public Participation Summary in Chapter 9). Additionally, the City of • Elevating all of the rail tracks above I-90 Interchange Alternative 3J, which was documented fully in the ENF. The Secretary’s Boston Planning and Development Agency (BPDA), in collaboration with MassDOT, • Reducing interstate highway standards Certificate on the ENF, along with public and agency comment letters, continued performed a placemaking study of the interchange concept. The placemaking study • Completely relocating SFR interaction with the Task Force, and the results of the BPDA Placemaking Study, led documents can be viewed on the City of Boston website, http://www.bostonplans.org/ • Considering alternative interchange configurations, including a diverging to a series of modifications and enhancements, resulting in the current I-90 Urban Interchange Preferred Alternative 3K with three Throat Area Variations. A more planning/planning-initiatives/i-90-allston-interchange. diamond interchange detailed description of the development of the Preferred Alternative follows. An The placemaking standards and master planning considerations in that study The guiding criteria used to develop the Preferred Alternative began with developing evaluation of the 3K Preferred Alternative and the advantages and disadvantages contributed to the further refinement of the interchange concept. The alternatives alternatives that met the overall Project Purpose and Need. Through interaction with associated with each of the three Throat Area Variations is provided in Chapter 5. development also considered future uses proposed by the landowner, including urban the Task Force, a set of priorities was developed that captured the defining elements development and potential for air rights construction over the railroad facilities. shared by MassDOT and the public and agency stakeholders represented on the Task 3.1.2 No Build Alternative This chapter is organized to provide a review of the conceptual development of the Force. The priorities include: As outlined in the ENF, the deteriorated I-90 viaduct is at the end of its serviceability. highway interchange Preferred Alternative and streets (3.1), the rail layover facilities • Improving safety for all modes (walking, cycling, driving, transit) The structural condition of the viaduct is such that this important piece of infrastructure and West Station (3.2), and finally, the three Throat Area Variations (3.3). • Realigning I-90 would be extensively rehabilitated if the Preferred Alternative is not implemented. Rehabilitation would include upgrading the viaduct’s original limited design load The No Build Alternative is included as a benchmark against which the impacts of • Including a context-sensitive design to: capacity to current structural capacity requirements. other alternatives are compared (see the Assessment of Impacts in Chapter 5). The ◦ lessen the impact of the interchange No Build Alternative retains all existing interchange infrastructure with the exception ◦ avoid inducing cut-through traffic with a new configuration Under the No Build Alternative, rehabilitation of the viaduct superstructure will result in of the existing I-90 viaduct, which due to its current severely deteriorated condition, ◦ reconnect sections of Allston to each other and to the Charles River similar lane and shoulder widths as the existing condition. A slight increase in the travel will require significant rehabilitation in its current location and configuration. • Protecting the neighborhood during construction way width will be achieved with new bridge railing and median barrier, and elimination A description of existing conditions, including I-90, Soldiers Field Road (SFR), rail yard, • Providing and improving accessible connections to PDW Path of the existing safety walks. The scope of the No Build Alternative will include this work Worcester Main Line and Grand Junction Railroad (GJR), is provided in Chapter 4. • Creating a more vibrant Cambridge Street that serves all modes only because the need exists in any case. The work will be limited to match existing infrastructure at the east and west ends of the viaduct within MassDOT’s current right- • Supporting future expansion of transit services of-way (ROW). The required extent of viaduct rehabilitation is described below. • Providing accessibility to transit at future West Station 3.1 Development of Highway/Streets Alternatives Under the No Build Alternative, it is assumed that the MBTA would establish a layover In the October 2014 ENF, MassDOT identified Concept 3J as the preferred interchange As detailed in the ENF, a set of criteria was employed to

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