I-495 at I-90 Interchange Improvements Design-Build

Hopkinton and Westborough, MA

The Interstate 495 (I-495) at Interstate 90 (I-90) interchange in Massachusetts is one of the state’s busiest interchanges, in need of critical geometric, safety, and operational improvements to enhance safety and mobility for travelers. Reconstructing the interchange while navigating complex environmental and regulatory requirements requires an integrated approach to project delivery, leveraging strong transportation engineering with sound environmental capabilities. MassDOT has entrusted VHB as lead designer for this nearly $400M Design-Build project—the largest project in the state—teamed with Barletta Heavy Division, Inc., O&G, and Aetna Bridge Company.

As tolling along 1-90 has transitioned from mixed-mode (cash/E-ZPass) to all electronic (AET), potentially impacting traffic demands, safety, and overall mobility, the need for improvements at the interchange has accelerated. The roadways are also in a highly sensitive environment, including an Area of Critical Environmental Concern (ACEC) and rare species habitat, which has required striking a balance in the redesign of the interchange that would improve safety and mobility while avoiding, minimizing, or mitigating any associated impacts to sensitive resources.

In addition to major interchange design, the project elements include 16 structures; accelerated bridge construction; traffic, utility, drainage, and highway engineering; public outreach and coordination; MBTA and freight rail coordination; as well as extensive wetland restoration, mitigation, and monitoring to comply with the environmental permits.

Screenshot of the proposed I-495/I-90 interchange.


  • Massachusetts Department of Transportation


  • Air & Noise Analysis

  • Alternative Delivery

  • Bridge Design & Engineering

  • Cultural Resources Assessment

  • Design-Build

  • Environmental Assessment

  • Environmental Compliance

  • Environmental Services

  • Highway/Roadway Design & Engineering

  • Interchange Design & Engineering

  • ITS Design

  • Landscape Architecture

  • Modeling

  • QA/QC

  • Stormwater Design & Engineering

  • Stream Restoration Design

  • Structures Design & Engineering

  • Traffic Engineering

  • Traffic Management & Operations

  • Traffic Safety Analysis

  • Wetlands Permitting