What could be considered a prehistoric artifact of the Interstate highway system is being brought up to the 21st century along Interstate 495 south of Boston.
Nine miles (14.4 km) of the northbound lane of the highway near Foxboro will have received a new asphalt surface by the time the project is completed in September 2004.
Ever since the road was first constructed in the early 1960s, the stretch now being scrutinized was made of concrete, just like so much of the Interstate system in those days. But it is now the only original piece of concrete road along I-495. In the meantime, everything else has been replaced.
“I’m not sure why it was done in concrete, but now it needs to be resurfaced,” said Doug Cope of the Massachusetts Highway Department (MassHighway).
Only the northbound lane has been affected so far. Work is planned in the future for the lanes headed south, which also is concrete, but that is still in the planning and design stages.
To do the job, Roads Corporation of North Billerica, MA, the primary contractor for the job, is using a rubblizer, a machine that does basically what its name says: turn the concrete into rubble. By using a drop hammer, the machine — an MHB Badger breaker — fractures the concrete. Stu McCormick, project manager of Roads Corporation, said that the machine was brought in and operated by Antigo Corporation of Antigo, WI.
Rubblizers eliminate the need to haul away the concrete that has been broken up because it can be used as the foundation for the new road. Once the concrete has been pulverized, asphalt is then poured over the top to create its new surface. The process saves contractors a good deal of money.
The MHB Badger breaker is a large machine utilizing 16 steel hammers attached to hydraulic lift cylinders. They are dropped on the pavement approximately once every two seconds to pound the concrete into small pieces. The hammers weigh up to 1,200 lbs. (540 kg) and can be dropped from a variety of heights as high as 5 ft., depending on the needs of the project.
The machine generally works on an 8-ft. (2.4 m) wide swath, although wings can be added to cover a total of 13 ft. (3.9 m). For narrow areas, the Badger breaker also can be set for just 2.67 ft. (.8 m). They also can be turned off for short distances to avoid striking things such as manhole covers.
On the top 3 to 4 in. (7.62 to 10.16 cm) of broken concrete, pieces are approximately 2 in. (5.08 cm) across, but they get larger as it goes deeper in the pavement, sometimes measuring 9 in. (22.86 cm) across on the bottom. The majority of pieces are 4 to 6 in. (10.16 to 15.24 cm) across.
Much of the other work will be done with traditional paving machinery, McCormick said.
Before the rubblizing started, temporary ramps were built and Route 1 at the Foxboro interchange was widened. The ramps included the King Street interchange in Franklin, Route 1A in Wrentham, Route 1 in Foxboro and I-95 in Mansfield.
One of the primary challenges is that the work is being done only at night. The Interstate is so busy during the daytime that work cannot be done safely then. A number of machines also will be used that will simply not be available during the daytime because they are needed elsewhere, McCormick explained.
I-495, also known as the Blue Star Memorial Highway, circumnavigates the outer corridor of Boston by traveling from Wareham and Taunton on the south side of the city, through Franklin, past Worcester and Framingham on the west and finishing on the north when it goes by Lowell, Lawrence and Haverhill. It rejoins Interstate 95 at Amesbury near the New Hampshire state line.
In addition, a number of bridges along the nine-mile stretch of highway will get new decks, which will be under the auspices of Roads Corporation. Subcontractors include Cosco of Rhode Island, which will do the guardrail work.
This is a major project for MassHighway, as shown by commissioner Matthew J. Amorello when the project was first announced.
“This major reconstruction project will make important roadway improvements to this section of I-495,” he said. “It will help this section of interstate highway meet demands of this rapidly growing area, and fulfills a commitment to the region.”
A total of $16.78 million has been allocated for the project, with 90 percent of it coming from federal moneys and the remaining 10 percent coming from state funds. The federal portion is that large because the Interstate highway system is part of the federal highway system.