Proposals for fixing I-495 and Route 9

State planners have drafted proposals for easing congestion and boosting safety at and around two interchanges on Interstate 495.

I-495 and Mass. Pike

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The problem

Vehicles exiting one highway and entering another must weave between other vehicles that are heading toward different ramps, creating congestion and leading to collisions.

Short-term recommendations

Install additional signs to give motorists directions to the proper toll lanes earlier in their approach to the ramps.

Flatten the curve of the onramp to I-495 northbound,
currently the site of frequent truck rollovers.

Estimated cost

$3 million

Long-term recommendations

Add a direct connection from I-495 north to the eastbound Mass. Pike (Interstate 90), eliminating the need for motorists making this connection to weave past other traffic.

Expand the I-495 south offramp and widen I-495 south’s onramp to reduce congestion.

Redirect the ramp for vehicles shifting from the westbound Mass. Pike to I-495 south, keeping them separate from other vehicles long enough to limit the need to merge and weave.

Estimated cost

$100 million

I-495 and Route 9

The problem

Some vehicles exiting I-495 must weave in between vehicles entering the highway, creating congestion and leading to crashes.


Add “braided” ramps that physically separate exiting traffic from oncoming traffic.

Estimated cost

$23 million to $25 million

Route 9 near i-495

The problem

Route 9 is congested along its stretch in Southborough and Westborough where it intersects with Interstate 495, a problem projected to become worse with more development.


Widen Route 9 between Computer Drive and Deerfoot Road.

Make improvements at several intersections, including signal upgrades and additional turning lanes.

Estimated cost

$8.4 million to $9.2 million for road widening

Intersection improvements vary by location.

SOURCE: Massachusetts Department of Transportation