About the Routes 27/9 interchange improvements, Natick

This project will replace the Route 27 bridge over Route 9 in Natick and reconfigure the interchange to increase safety, improve mobility and ease congestion.

Table of Contents

Overview

  • Replacing the existing Route 27 bridge over Route 9 with three independent bridge structures:
    • One bridge for Route 27 northbound vehicular traffic
    • One bridge for Route 27 southbound vehicular traffic
    • One bridge to accommodate a shared use path facility
  • Replacing the existing partial clover leaf interchange with a modified diverging diamond configuration.
  • Four transit stops (two along Route 9 and two along Route 27) with corresponding bus shelters for the MetroWest Regional Transit Authority (MWRTA).
  • Providing a shared-use path along the south side of Route 9 that will connect the Route 27 interchange area with the Cochituate Rail Trail (at the westerly project limit) and the MathWorks campus (at the easterly project limit).
  • Providing a new sidewalk along the north side of Route 9 within the project limits.
  • From Bacon Street to Rutledge Road, the project will provide a continuous shared use path along one side of Route 27 and a sidewalk along the other side.
  • Providing pedestrian-actuated warning systems at multiple crosswalk locations to increase driver awareness and yielding of crossing activity.
  • Providing two new traffic signals along Route 27 to accommodate the Route 27 crossing traffic (associated with the function of the modified diverging diamond).
  • Reconfiguring and improving access between Lakeshore Road and Route 27.
  • Reconfiguring the traffic signal at Route 27 at the 9/27 Exchange Driveway.
  • Reconfiguring the Route 9 on/off ramps to provide increased deceleration and acceleration lengths.
  • Upgrading and/or replacing existing drainage infrastructure along both Route 27 and Route 9 within the project limits.
  • Replacing the existing median barrier along Route 9.
  • Other ancillary items including low maintenance landscaping, stormwater improvements, retaining walls, guardrail, pedestrian fencing, new signage and new pavement markings.

Public Process and Background

In June 2017, the original 25% design was presented to the public at a Design Public Hearing, which received significant negative feedback on the proposal at that time. In response to these concerns, MassDOT engaged a new design firm, GPI, to evaluate additional alternatives. Two of those alternatives, a partial cloverleaf with roundabouts and a modified diverging diamond interchange (DDI) were presented at a workshop style Public Information Meeting in June 2019. Based on the feedback from that meeting, MassDOT advanced the design of the modified diverging diamond interchange. This updated design was presented at a Design Public Hearing in June 2023. In 2024, the project was advertised as a design-build project and was awarded to a joint venture design-build team consisting of McCourt Construction and Jacobs Engineering (McCourt-Jacobs). The first Public Information Meeting with the design-build team took place on November 24, 2024, ahead of the start of construction.

Project History

DateDescription
May 2011Project Initiation
June 2017Original 25% Design and Design Public Hearing
June 2019Public Information Meeting
June 2021Presentation to Town of Natick Transportation Advisory Committee
May 202225% Resubmission Package
June 2023Design Public Hearing
August 2024Best Value Design-Build Award
September 2024Notice to Proceed (NTP) - McCourt-Jacobs
November 2024Public Information Meeting #1 - Construction Phase

Project Goals and Needs

As part of the alternatives analysis conducted prior to June 2019, the project team developed a list of project needs and goals based on the existing conditions and public feedback from the first Design Public Hearing in 2017. The Project Needs and Goals are:

  • Bridge Replacement
  • Increase Safety
  • Improve Mobility
  • Reduce Congestion

First, the bridge that carries Route 27 over Route 9 is near the end of its useful life and needs to be replaced. Additionally, the existing bridge that carries Route 27 over Route 9 does not meet Federal requirements for vertical clearance. The project design includes raising the profile of Route 27 so this requirement can be met. During the evaluation of alternatives for the bridge replacement, the challenge of construction staging was identified. A key advantage of the modified Diverging Diamond Interchange (DDI) is that the new eastern bridge can be built “off-line”, eliminating the need for a temporary bridge during construction.

Enhancing safety for all users at this location is a key project need, with the goal of reducing congestion at the interchange. The on ramps to Route 9 have been identified as the first and second highest crash locations in the Town of Natick, with over 100 crashes occurring annually. The project will address this by eliminating the weaving condition that occurs on Route 9 caused by the Route 27 on and off ramps. This will be achieved by reducing the number of ramps and adding deceleration and acceleration lanes on Route 9, so that traffic doesn’t need to stop before entering Route 9. On average, over 80,000 vehicles travel through this interchange each day. During peak weekday travel times, Route 27 experiences significant delays, with vehicles frequently queueing on the Route 9 on-ramps. Studies have shown that DDI’s can reduce delays from 15-60 percent . This project will provide a more efficient design to better manage this demand while safely accommodating all mobility needs of the community.

The project will improve mobility and provide a safer, more comfortable experience for pedestrians and cyclists. The project includes a continuous and accessible pedestrian and cyclist (shared-use) path, and a dedicated shared-use path bridge. On Route 9, the project will extend the shared use path from the Cochituate Rail Trail to the MathWorks campus. This shared use path will also connect to local schools on the north side of the interchange, a feature that was identified by the public during the design development and is incorporated into the project. 

Design-Build Project Delivery

This project will be completed using the design-build project delivery method, where a single team manages both the design and construction. This integrated approach combines final design and construction into one phase, eliminating the need for a separate construction bid based on finalized plans and specifications. By streamlining the process, design-build reduces project timelines and fosters collaboration among designers, contractors, and MassDOT team.

Design-build contracts are procured using a Base Technical Concept (BTC) and a request for proposals that details performance requirements. The design-build team’s proposal must meet or exceed the Base Technical Concept. In August 2024, MassDOT awarded the best-value design-build contract to McCourt Construction and Jacobs Engineering.

McCourt-Jacobs, in partnership with MassDOT, will work together through the remaining phases of the project, which include final design and construction. This delivery method also enables the contractor to begin early construction on some items while final design is still underway. MassDOT is utilizing design-build more frequently because it promotes innovation, reduces the owner’s project risk, and expedites project delivery.

Design-Build and Design-Bid-Build charts

Contact   for About the Routes 27/9 interchange improvements, Natick

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