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Project background: I-495/I-90 interchange improvements

Issues and concerns for the I-495/I-90 interchange improvements project

Safety & Traffic

This interchange is a high-crash location, with 460 crashes between 2011 and 2015, including two that were fatal. A large number of these crashes occurred when interchange traffic backed up onto I-495, often during holidays and peak commuting times.

Many of the safety and capacity concerns result from:

  • Ramp layout
  • Weaving movements
  • Vehicle merging

Improvements as part of this project will help to address these concerns and reduce crash rates - saving lives, health, time, and money.

Freight, commerce, & economic development

Nearly half of the trucks entering eastern Massachusetts use this interchange. A goal of this project is to make improvements to this interchange which will substantially benefit the distribution of goods and services throughout the state. In turn, this will help facilitate both regional commerce and anticipated local growth.


The conversion of the Mass Pike to AET has improved traffic flow between I-495 and I-90. Because vehicles no longer stop to pay tolls, vehicle emissions are reduced. With the removal of the toll plaza, MassDOT is now positioned to improve the interchange geometry. In other words, AET has laid the foundation to improve the interchange safety, traffic, freight commerce and economic development.

Environmental Context

The areas in-and-around the interchange contain many sensitive environmental resources. These include the:

  • Cedar Swamp Area of Critical Environmental Concern (ACEC)
  • Areas of designated open space
  • Sudbury River riverfront, with floodplain, wetlands, and priority habitat for endangered & threatened species

This project aims to avoid or minimize impacts to these resources, and provide mitigation for any unavoidable impacts.