The Massachusetts Department of Transportation (MassDOT) recently held a virtual meeting detailing the beginning of the construction phase of the remodeled interchange between Interstate 495 and Interstate 90, which straddles the towns of Hopkinton and Westborough southwest of Boston.
As part of the project, one of Hopkinton's two Fruit Street bridges is undergoing reconstruction (the other currently is being redesigned). The result is that the area is closed to traffic and will remain so for a few more months, MassDOT told the Hopkinton Independent.
"The Fruit Street bridge will be replaced in two major stages," explained Donald Cooke, the project's design manager of Watertown-based engineering firm VHB.
He added the Hopkinton bridge construction will be performed with one alternating lane of traffic open during the building period. Roadway, utility work and landscaping are all included.
Nearby, the upper part of the structure of the Flanders Bridge in Westborough will be replaced as well, Cooke noted.
During the question-and-answer period, Barry Lorion, MassDOT's District 3 highway director of central Massachusetts, clarified that there are two projects that involve Fruit Street. Separate from the first project is the ongoing reconstruction of the second Fruit Street bridge.
One commuter to Hopkinton, George Allegrezza, noted the current steep incline at the merge point to get onto I-495 south. He told MassDOT there is a "very tight radius" to get into this incline and a narrow merge lane which is difficult for delivery trucks to navigate.
"Traffic following the trucks tends to pop out, move left one or two lanes, and accelerate quite rapidly up the hill," he explained, while expressing his hope that the new configuration would address the issue.
In answering Allegrezza's concern, Cooke explained that all the radii for the ramps were tight because people had to stop to pay their tolls manually.
"I could tell you with some confidence that every one of the ramps will have better radii more suited to the speed that people would like to drive — not high speed," he said.
Because of the sheer traffic volume, Fruit Street project will not include accelerated bridge replacement strategies because the bridges need to remain open. In urban projects, Cooke noted that a bridge structure could be closed for a weekend for more rapid construction, but that is not feasible in this case.
Congestion, Poor Geometry Led to Interchange Rebuild
Interestingly, the I-495/I-90 Interchange Improvement project is the first complete interstate-to-interstate interchange effort that the transportation agency has undertaken in its history.
"This is one of the largest projects that MassDOT has ever advertised for construction since its inception in 2009," Lorion said.
The project's radius is three-quarters of a mile from the interchange point, he noted.
More than 200,000 vehicles pass by or through the interchange on an average day, according to MassDOT, which includes 50 percent of the state's commercial traffic. The need for a reconfiguration of the interchange arose after the removal of toll booths and the installation of the E-Z Pass electronic tolling system.
The goal of the nearly $300 million project is to alleviate what Lorion called "chronic congestion" and correct "substandard geometry" that currently contributes to crashes and rollovers on both roadways, the Hopkinton news source reported Nov. 30.
To improve those issues, the roadways' on-ramps and off-ramps will be lengthened to provide smoother access for vehicles, and traffic no longer will have to weave through the old toll areas once the project is complete.
MassDOT terms the I-495/I-90 interchange upgrade as a design-build project because construction and design elements will happen simultaneously over the course of the next five years. Public meetings will be scheduled to explain the process throughout the build, the state agency's team members said in November.
"We will completely replace the interchange, and it will be unrecognizable from what you see today," Lorion noted.
Work to Begin Before New Year
Cooke said construction will begin before the end of the year on I-90's on-ramps and off-ramps. Fiber optic cables will move from the median of I-90 to outside its westbound shoulder, as well as from I-495's median from the Massachusetts Pike/I-90 to outside of I-495 southbound.
The current three-lane configuration for each direction of the two interstates will remain, he added. A temporary lane will be installed to help traffic flow during the construction period, the Hopkinton news source learned. Additionally, the number of lanes will not be increased by the project because of the proximity of sensitive environmental resource areas, including Whitehall Brook, and other wetlands and floodplains.
The bridges over Whitehall Brook in Hopkinton and the MBTA commuter rail station in Southborough are slated to be completely replaced, Cooke continued, adding there will be "minor horizontal and vertical changes" for the new single-lane ramps. Where the on-ramps and off-ramps converge, they will form double lanes.
New construction will take place on I-495 northbound within the existing median, Cooke made public, while the southbound side will stay as it is. This allows space for the staging of traffic throughout the construction period, he said. Crews will build an auxiliary lane northbound from the interchange to Massachusetts Route 9, and there will be a new direct lane from I-495 northbound to I-90 eastbound.
The freeway interchange upgrade also will include a new loop ramp from I-495 southbound to I-90 eastbound, part of a two-lane offramp that will enter I-90 as a single-lane onramp.
