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Improving Regional Connections and Mobility in the Boston Metro Area

View of the aging viaduct, highway to be realigned, and former rail yard slated for redevelopment in the Boston area
Tetra Tech is leading a multi-consultant team for the Allston Multimodal Project to improve Interstate 90 connections, increase safety and accessibility for all travel modes, and enable future development.


The Massachusetts Department of Transportation (MassDOT) is undertaking a more-than-$1.9 billion transformative highway interchange project to replace an aging viaduct, realign a major regional connection into Boston, construct a new commuter rail station and layover facility, and improve livability and connectivity for residents.


Tetra Tech developed an extensive series of complex infrastructure alternatives, performed comprehensive traffic engineering analysis, conducted detailed stormwater analysis, prepared the accelerated delivery of National Environmental Policy Act and Massachusetts Environmental Policy Act filings, and provided highway and bridge design and hazardous materials assessment services. We worked closely with Central Transportation Planning Staff to develop a comprehensive traffic model to test various interstate highway, ramp, and local street network alternatives. The traffic analysis considered multiple options to realign the existing highway and interchange ramps and helped set the foundation for the project alternatives included in the accelerated delivery of state and federal environmental review filings. Tetra Tech also prepared comprehensive construction staging designs that are being advanced as part of the Base Technical Concepts for design-build procurement.

Tetra Tech continues to support MassDOT through an unprecedented public outreach and participation process, and has advanced the project in close coordination with MassDOT and Federal Highway Administration leadership.


  • 28 infrastructure alternatives developed focusing on multimodal improvements
  • 45 intersections analyzed that included preparing traffic micro-simulations
  • Stormwater analysis for more than 140 acres of urban watershed
  • Prepared comprehensive construction staging plans
  • Coordinated with 45 member Allston Multimodal Project task force

The project creates an opportunity to dramatically improve livability and connectivity for residents of the Allston neighborhood while preserving and enhancing regional mobility.

MassDOT website
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