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This 2002 photo shows the northbound Outer Circumferential Highway (I-495) at EXIT 34 (MA 110 / Chelmsford Street) in Chelmsford. (Photo by Jim K. Georges.)

AN OUTER LOOP FOR EASTERN MASSACHUSETTS: In the late 1940's, as plans were being developed for an expressway network to serve Boston and its inner-ring suburbs, the Massachusetts Department of Public Works (MassDPW) announced plans for an outer bypass of the Boston area. The commonwealth stated the purpose of the outer bypass as follows:

This looping 87.3-mile-long expressway, in effect the third belt highway around metropolitan Boston, also serves as a vital connector to the great industrial cities of the Merrimack Valley-Haverhill, Lawrence and Lowell. In its western sweep some 30 miles from Boston, it will pass close to Worcester, and swing south and east again to serve Milford and other manufacturing areas in the south-central area. Thus, the loop, in addition to bypassing the heavily urbanized areas of the north, will provide a much-needed boost to the economic development of the cities and towns it serves by providing swift, easy access to all parts of the state and the nation.

Stretching from Salisbury to Foxborough, the "Relocated Route 110" was to be routed through a mix of industrialized and lightly populated areas roughly along a 30-mile radius of Boston. It was to supplement the "Relocated Route 128" (Yankee Division Highway), which was being built to serve towns and inner-ring suburbs roughly along a 15-mile radius of Boston, and the proposed (but never built) Inner Belt Expressway (I-695) in the urban core.

Since the proposed outer loop connected at both ends to the "Relocated US 1" - the future I-95 - the MassDPW submitted the route to the Federal Bureau of Public Roads (BPR) for inclusion into the Interstate highway system. The BPR approval guaranteed 90 percent Federal funding for the $125 million highway; the commonwealth was to pay the remaining costs. In 1958, the MA 110 Expressway received the I-495 designation.

At the same time, the MassDPW developed plans for a new MA 25 Expressway (originally called "Relocated Route 28" southeast of Raynham), which was to connect the I-95 / I-495 in Foxborough with the Bourne Bridge in Buzzards Bay, at the gateway to Cape Cod. Although the MA 25 Expressway was to continue the route of I-495 to the southeast, it was not included in the Interstate system at the onset.

This 2006 photo shows the dual-deck O'Reilly Bridge over the Merrimack River in Lawrence. The upper deck carries the I-495 mainline, while the lower deck carries C/D roads for exits on both sides of the river. (Photo by Steve Anderson.)

DESIGN AND CONSTRUCTION: With few of the restrictions that were encountered in building urban freeways, the MassDPW was easily able to acquire a 300-foot-wide to 400-foot-wide right-of-way for the construction of I-495 and MA 25. The adoption of widely spaced exits, gentle curves and variable wooded medians was well suited to the semi-rural character of the area. In the urbanized areas to the north and west, exits were spaced closer together. Throughout the route, the same Interstate-standard design specifications applied for lane and shoulder widths, acceleration-deceleration lanes and bridge clearances.

ROADWAY LAYOUTS AND TRAFFIC COUNTS: The different sections of I-495 are described as follows:

  • EXIT 1 (I-195 and MA 25 Expressway) in Wareham to EXIT 7 (MA 24 / Fall River Expressway) in Raynham: This four-lane section of I-495 was originally constructed as part of the MA 25 Expressway. The first sub-section, from EXIT 3 (MA 28) in Middleboro north to EXIT 6 (US 44) in Taunton, opened to traffic in 1959. The completed section was extended north to EXIT 7 (MA 24 / Fall River Expressway) in 1963, and south to EXIT 1 (I-195 and MA 25 Expressway) in 1967. According to the Massachusetts Highway Department (MHD), this four-lane section, which was re-designated I-495 in 1982 upon completion of the Raynham-to-Foxboro section, carries approximately 40,000 vehicles per day (AADT).

  • EXIT 7 (MA 24 / Fall River Expressway) in Raynham to EXIT 13 (I-95) in Foxboro: Originally planned as part of the MA 25 Expressway, this section was added to the Interstate highway network in 1975 following the cancellation of I-95 and I-695 through Boston. The construction of this section of I-495 included the reconstruction of nearby MA 140 in the Foxboro-Mansfield area. This six-lane section was the last to be completed when it opened to traffic in 1982; it now carries approximately 60,000 vehicles per day.

  • EXIT 13 (I-95) in Foxboro to EXIT 23 (MA 9) in Westborough: The final original section of I-495 (under the 87-mile plan devised in 1948) opened to traffic in 1969. A new EXIT 22 in Hopkinton for the Massachusetts Turnpike (I-90) was included in this project. This six-lane section carries approximately 70,000 vehicles per day.

  • EXIT 23 (MA 9) in Westborough to EXIT 29 (MA 2) in Littleton: This six-lane section, which opened to traffic in 1964, carries approximately 90,000 vehicles per day. (A new EXIT 25 in Marlborough for I-290 / Worcester Expressway opened to traffic in 1970.)

  • EXIT 29 (MA 2) in Littleton to EXIT 31 (MA 225) in Westford: The first section of I-495 (under the Federal Interstate program) to be completed, this six-lane section, which was completed in 1961, carries approximately 90,000 vehicles per day.

  • EXIT 31 (MA 225) in Westford to EXITS 36 A-B-C (US 3 / Northwest Expressway and Lowell Connector) in Chelmsford: Completed in 1962, the opening of this section of I-495 coincided with the completion of the Lowell Connector, a four-lane spur into Lowell. This six-lane section carries approximately 105,000 vehicles per day.

  • EXITS 36 A-B-C (US 3 / Northwest Expressway and Lowell Connector) in Chelmsford to EXIT 42 (MA 114) in North Andover: A short sub-section in the vicinity of EXIT 40 (I-93 / Northern Expressway) opened to traffic in 1962. The entire six-lane section from Chelmsford to North Andover, which opened to traffic in 1963, carries approximately 115,000 vehicles per day.

  • EXIT 42 (MA 114) in North Andover to EXIT 53 (Broad Street) in Merrimac: This six-lane section carries approximately 90,000 vehicles per day. Completed in 1964, this section included the construction of three bridges across the Merrimack River, as well as the Haverhill Connector (spur to MA 125). Unique among these bridges is the O'Reilly Bridge, which crosses the Merrimack River between EXIT 44 (Merrimack Street) and EXIT 45 (Marston Street) in Lawrence. The O'Reilly Bridge is a 1,050-foot-long, double-decked span that carries six lanes of I-495 on the upper level, and four lanes of collector-distributor (C/D) roads on the lower level.

  • EXIT 53 (Broad Street) in Merrimac to northern terminus (I-95) in Salisbury: This northerly section of I-495 was completed in 1967. Six lanes of I-495 narrow to four lanes north of EXIT 55 (MA 110) in Salisbury, just prior to the I-495 / I-95 junction. This section carries approximately 60,000 vehicles per day.

The speed limit throughout the 120-mile-long length of I-495 has been 65 MPH since the late 1990's, except through the Lawrence area (where the speed limit remains 55 MPH).

This 2008 photo shows the southbound I-495 (Outer Circumferential Highway) at EXIT 25 (I-290 / Worcester Expressway and MA 85 Connector) in Marlborough. (Photo by Steve Anderson.)

HISTORY REPEATS ITSELF ON THE OUTER BELT: As early as the 1950's, town boards anticipated the need to accommodate growth along what was then called the "Relocated Route 110." Local officials cited the need for zoning changes and utility enhancements to promote development along the corridor.

In the past three decades, the I-495 corridor has become the fastest growing area in Massachusetts. Mirroring the experience of MA 128 (Yankee Division Highway), technology firms established factories along the Outer Circumferential Highway. However, this is where the similarity ends. Where in recent decades, growth along the MA 128 corridor has been concentrated in software and related services, the growth along the I-495 corridor has emanated from hardware manufacturing and communications.

Growth along the I-495 corridor has come at a price, however. Attempts to develop regional plans along the corridor for development, services and resource management have clashed with traditional New England "home-rule" principles long held by towns along the route. Congestion along I-495 also has become chronic: between 1977 and 1997, traffic counts along I-495 have doubled, tripled, and (along some sections) even quadrupled.

This 2001 photo shows I-495 (Outer Circumferential Highway ) at EXITS 11-12 (MA 140) in Mansfield. Originally planned as part of the MA 25 Expressway, this final section of I-495 was completed in 1982. (Photo by Alexander Svirsky,

CURRENT AND FUTURE IMPROVEMENTS: The MHD has undertaken the following projects on I-495 to improve safety and access:

  • EXIT 1 (I-195 and MA 25): In 2005, the MHD began a $1 million study to study possible improvements to the southern terminus of I-495 in Wareham.

  • EXITS 11-12 (MA 140): The existing interchange is not accessible from all directions: the movements from northbound I-495 to southbound MA 140, and from northbound MA 140 to southbound I-495, are missing. A proposal supported by the town of Norton would supply the missing movements, alleviating chronic congestion before and after concerts at the Tweeter Center in Mansfield. However, Mansfield officials oppose the plan, citing that the road improvements would attract commercial development and disrupt residential areas (eight homes would need to be acquired).

  • EXIT 13 (I-95) in Foxboro to EXIT 17 (MA 140) in Franklin: In 1997, the MHD began work to replace an old and experimental section of concrete roadway with asphalt along nine and one-half miles of I-495 through this area. The work has temporarily reduced I-495 from three to two lanes in each direction. During the summer of 2002, six deaths occurred in the construction zone, prompting officials to consider a 50 MPH speed limit, as well as improved signing and lane striping, through the area. The $17 million project was completed in 2004.

  • EXIT 23C (Crane Meadow Road) in Marlborough): In 2001, the MHD completed construction of a new EXIT 23C to link I-495 with a nearby industrial park in Marlborough. The $13 million, three-level "semi-directional T" interchange was designed to provide access only to the industrial area to the west of I-495, in order to prevent interference with residential neighborhoods east of the highway.

  • EXIT 25 (I-290 / Worcester Expressway): In 2000, the MHD installed large warning signs to inform motorists of the left-hand ramp connecting eastbound I-290 to northbound I-495. The curved one-lane ramp, whose sight distance is compromised by the geography of the area, has been the site of many accidents over the years. (This ramp was intended as a replacement for a dangerous loop ramp when it was built in 1978.) A complete re-design of the interchange, in which the geometry (specifically, the curve radii) of the ramps would be improved, is years away, and is expected to cost $30 million.

  • EXITS 36 A-B-C (US 3 / Northwest Expressway and Lowell Connector): The MHD built new bridges to carry I-495 over US 3 as part of the Northwest Expressway reconstruction and widening project. The reconstruction of the I-495 bridges over US 3 was completed in 2003; the US 3 widening project was completed two years later.

  • EXIT 43 (Massachusetts Avenue) in North Andover to EXIT 45 (Marston Street) in Lawrence: The MHD is rehabilitating the dual-deck O'Reilly Bridge, extending and realigning the ramps at EXIT 44 (Merrimack Street / Sutton Street), and building new ramps at EXIT 45. The $31 million project is scheduled for completion in 2007.

By 2025, the I-495 corridor may be chronically congested due to continued economic growth. While widening I-495 from six to eight lanes has been suggested, various fiscal and environmental costs involved with such an undertaking make such widening doubtful. Future improvements on I-495 likely will be related to interchanges and their operation.

This 2002 photo shows the northbound I-495 (Outer Circumferential Highway) approaching EXIT 5 (MA 18) in Middleboro. This four-lane section opened in the late 1950's as the MA 25 Expressway; it did not become I-495 until 1982. Note the legacy guide sign (all in capital letters) for EXIT 5 on the right, dating back to the MA 25 era. (Photo by Douglas Kerr,

At EXIT 25 (I-290 / Worcester Expressway) in Marlborough, new ramps should be constructed to permit two-lane access from I-290 eastbound to I-495 northbound, and from I-495 southbound to I-290 westbound.

The existing cloverleaf interchanges at EXIT 13 (I-95) in Mansfield and at EXIT 40 (I-93 / Northern Expressway) in Andover should be reconstructed, either by constructing collector-distributor (C/D) roads on the intersecting freeways, or by constructing new four-level stack interchanges. Right-of-way could be easily acquired for expansion and safety improvements at these interchanges.

SOURCES: "A Report of Progress," Massachusetts Department of Public Works (1962); Recommended Highway and Transit Plan, Massachusetts Department of Public Works (1968); "The Massachusetts Highway Story (1949-1969)," Massachusetts Department of Public Works (1969); "Proposed Interstate 495 and Relocated Route 140, Draft Environmental Impact and 4(f) Statement," Massachusetts Department of Public Works (1974); "Short Circuits," The Boston Globe (12/26/1982); "The 495 Region: Building an Identity," Massachusetts Technology Collaborative and Metropolitan Area Planning Council (1999); "Danger Foreseen at I-290 / I-495 Interchange" Elaine Thompson, The Worcester Telegram and Gazette (1/21/2000); "Mansfield, Norton Disagree on I-495 Interchange Improvements," The Associated Press (6/25/2000); "Interstate 495: The Challenges of Change in an Information Technology Corridor" by Sarah Kuhn, Massachusetts Benchmarks (October 2000); "Fatalities Show Need to Slow Traffic on I-495" by Mac Daniel, The Boston Globe (8/25/2002); Massachusetts Highway Department; Modern Continental Construction Company; Southeastern Regional Planning and Economic Development District; Vollmer Associates; John Cairns; Dan Moraseski; Scott Oglesby; Paul Schlictman; Alexander Svirsky.

  • I-495 shield by Ralph Herman.
  • MA 110 and MA 25 shields by Barry L. Camp.
  • Lightposts by Millerbernd Manufacturing Company.




  • I-495 (Massachusetts) exit lists (northbound and southbound) by Steve Anderson.


  • Outer Circumferential Highway (I-495)

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