Drivers on Interstates 90 and 495 in the Bay State will see more construction equipment during their commutes as work on improving the interchange connecting the two highways is currently at a high point, according to the Massachusetts Department of Transportation (MassDOT).
The construction is part of a five-stage plan (numbered 0 through 4) that seeks to replace the current interchange southwest of Boston with a new one designed to improve travel time and reduce traffic congestion and crash rates in the area.
Although MassDOT has not released exact figures, it has said the project is the largest in the state's history, with some estimates putting its cost at approximately $400 million.
The state agency expects the project to be finished by June 2027 with the second phase of construction set to begin soon, an agency official told MassLive in early August.
"There is no set date when the project transitions [from Stage 1], but based on the work, the crossover signals the start of moving into Stage 2," the spokesperson explained. "Stage 1 work is formally scheduled to conclude by [this September]."
Located between the towns of Hopkinton and Westborough, the interchange is considered by MassDOT to be "key for freight and commerce." The department's website noted that more than 100,000 vehicles travel on both I-90 and I-495 daily, including approximately half of the trucking that enters eastern Massachusetts.
The current design of the interchange concentrates traffic through a former toll booth plaza and several weaving parts, which are set to be removed as part of the improvements.
"Weaving parts are essentially where vehicles change lanes and merge as they enter, exit the highway, or approach the old tolling area," according to MassDOT. "Therefore, eliminating the old toll booth area and improving the spacing and lanes mitigates queueing and crashes."
While the work is under way, the department urges drivers to be ready for traffic changes in the area and to expect delays.
To mitigate any traffic impacts, all ramp connections between the two interstates will be maintained during construction, along with three lanes on the mainlines — with the exception of short-term closures during approved off-peak hours, MassDOT said on its website.
Additionally, signage and markings will be in place to help direct drivers. During the night, temporary lighting will assist motorists in navigating the roads.
The transportation department also has established a plan to keep noise at baseline sound levels throughout the project area.
Interstate Project Made Up of Many Parts
The I-90/I-495 interchange improvement project also involves the construction of new ramps and bridges, including the replacement of the Fruit Street bridge over I-495 and the bridge that crosses over Flanders Street.
The interchange project's design began in May 2022 and will continue through the end of this year. As soon as the plans for each of the five stages are completed and reviewed, MassDOT said, work on the project segments will get under way.
So far, Stage 0, which lasted from October 2022 to April 2023, involved fiber relocation and temporary ramp construction.
Stage 1 began in December 2022 with the first phase of work focused on building the Fruit Street Bridge across I-495. With that accomplished last spring, the construction team began traffic relocation work following the completion of utility work being undertaken by subcontractors. That allowed Phase 2 work on the bridge to resume.
The freeway's new median bridge also is nearing completion, MassDOT noted, and the interstate's southbound traffic is being relocated to a temporary median crossover to enable the project team to commence construction activities on the southbound shoulders of I-495.
Future construction stages around the I-495/I-90 interchange will include:
- An elimination of the old toll booth area and weaving areas created by the current design.
- Improved ramp spacing, acceleration and deceleration lanes, and elimination of weaving movements.
- A new I-495 bridge over I-90.
- New I-495 and I-90 bridges over the Massachusetts Bay Transit Authority (MBTA) and CSX/Amtrak lines.
- An auxiliary lane from northbound I-495 to Mass. Highway 9.
- A new I-495 northbound bridge over Flanders Road.
- Upgrading or replacing 11 loop ramps on the interstates.
- The restoration and mitigation of environmental resource areas.
In total, the I-495/I-90 interchange effort will cost $466 million, MassDOT said.
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