What is the busiest highway in Massachusetts?

By John DiBartolo on September 12, 2025

Massachusetts is one of the most densely populated and economically active states in the Northeast, with a complex network of highways, parkways, and turnpikes that facilitates the daily movement of millions. As a result, traffic congestion is a daily challenge for residents, commuters, and long-distance travelers.

What is the busiest highway in Massachusetts that stands out as the most traveled and most congested? The answer is: Interstate 93 (I-93). If you or someone you love has been injured due to another driver’s negligence, you should choose a Massachusetts personal injury lawyer with a record of successfully representing car accident victims.

Overview of Massachusetts Highway Infrastructure

Massachusetts has more than 36,000 miles of public roadway, with key interstates and state highways forming the backbone of its transportation system. The most significant of these highways include:

Interstate 93 (I-93): Runs north-south from the New Hampshire border through Boston into southeastern Massachusetts.
Interstate 90 (I-90 or Mass Pike): The east-west corridor connecting Boston to Springfield and beyond into New York.
Interstate 95 (I-95): The circumferential highway skirting Boston’s outer metropolitan region.
Route 128: Historically considered Boston’s original ring road, it now overlaps with portions of I-95.
Route 3 and Route 24: Important regional corridors with high commuter traffic.

Despite this advanced network, Massachusetts consistently ranks among the worst U.S. states for traffic congestion, particularly in and around the Boston metropolitan area.

Interstate 93: The Epicenter of Massachusetts Congestion

Geographic Reach and Strategic Importance

I-93 begins in Canton, Massachusetts, and travels north through Boston, Medford, Stoneham, and Andover before entering New Hampshire. As a major north-south corridor, it connects Boston to both southern and northern suburbs, as well as to neighboring New England states. The highway serves as a primary commuting route for:

Residents of Boston’s North Shore and Merrimack Valley
Workers commuting into Boston from southern New Hampshire
Trucking and commercial traffic moving between Massachusetts and Canada

Daily Traffic Volumes and Congestion Data

Sections of I-93 in downtown Boston carry more than 250,000 vehicles per day. This includes both commuter vehicles and heavy freight trucks, making I-93 one of the most trafficked urban highways in New England. The highest congestion levels are typically observed during:

Weekday mornings (6:30 AM – 9:30 AM) heading southbound into Boston
Weekday evenings (3:30 PM – 7:00 PM) heading northbound toward the suburbs
Fridays and Sundays, when leisure travelers and weekend commuters add to volume

Notable Congestion Points on I-93

The Central Artery (Boston)

The most notorious portion of I-93 is the stretch that cuts through downtown Boston, known as the Central Artery. This segment was once an elevated highway, but after the completion of the Big Dig project, much of it now runs underground. Despite the infrastructure improvements, congestion remains significant due to:

Narrow lane widths and tunnel merges
Influx of traffic from I-90 and the Ted Williams Tunnel
Interchange complexity with Route 1 and Storrow Drive

The Zakim Bridge and Charlestown

The Leonard P. Zakim Bunker Hill Memorial Bridge, which carries I-93 over the Charles River, is another high-traffic choke point, according to the Massachusetts Department of Transportation. The bridge handles thousands of vehicles per hour during rush periods and connects key routes into East Boston and Logan International Airport.

The Medford to Andover Corridor

This portion of I-93 sees extensive traffic from commuters and big rigs, making it one of the dangerous roads in the region. Intersections with I-95/Route 128 in Woburn and Route 495 in Andover create intense merging activity that generally causes bottlenecks and delays.

I-93 Accident Trends and Safety Risks

Collision Frequency

Due to high traffic density, variable speeds, and short merge lanes, I-93 is a hotspot for:

Rear-end collisions
Sideswipes during lane changes
Chain-reaction crashes during inclement weather
Accidents involving commercial trucks and delivery vans

Certain stretches of I-93 account for more crashes per mile than any other highway in Massachusetts, particularly during peak commuting hours and bad weather.

Fatal and Serious Injury Crashes

Fatal crashes, although less frequent, usually occur at higher speeds in less congested areas north of Boston. In urban segments, serious injuries are commonly linked to:

Speeding in express lanes
Distracted driving during stop-and-go traffic
Sudden lane changes or aggressive merging

In tunnels and narrow sections, emergency response is also delayed, increasing the severity of injuries.

Comparative Analysis: I-93 vs. Other Major Highways

I-90 (Massachusetts Turnpike)

Toll-supported, wider shoulders, longer merge lanes
Traffic load is high, but distributed due to less urban density west of Boston
Congestion Hotspots: Newton, Framingham, and Allston-Brighton toll areas
Crash Frequency: Lower per mile than I-93, but more accidents involving long-haul trucks

I-95 / Route 128

Function: Boston’s partial beltway and suburban bypass
Traffic Density: Extremely high during rush hours
Notable Congestion Areas: Dedham, Waltham, Peabody interchanges
Crash Risk: High due to frequent on/off ramps, commercial vehicle density

Route 3 and Route 24

Function: Regional highways serving South Shore and South Coast
Congestion: Significant, especially near the Braintree split and Brockton
Accident Trends: High-speed rollover and median-crossing crashes are more common

While these highways are busy, none match I-93’s urban congestion intensity, strategic connectivity, and accident risk per mile.

Urban Development and Infrastructure Pressure

Boston’s Role as a Traffic Generator

Boston’s compact downtown core, limited parking availability, and dense residential zones contribute to high I-93 usage. With major employment centers, universities, and medical facilities located within city limits, there is persistent daily inflow and outflow traffic. Despite a strong public transportation system (MBTA), ridership limitations and service disruptions push more commuters onto highways.

Limited Alternative Routes

Unlike other major metro areas, Boston has relatively few parallel expressways. This means:

I-93 remains the default route for most north-south travel
Local surface roads like Route 1 or Route 28 offer limited relief
When I-93 is blocked by an accident, backups may last for hours

Roadwork and Weather Complications

Seasonal Construction

MassDOT frequently schedules roadwork on I-93 during warmer months. While necessary for safety and maintenance, such projects may:

Narrow lanes or close shoulders
Require overnight or weekend detours
Create sudden traffic stoppages that lead to rear-end crashes

Winter Hazards

Massachusetts winters introduce snow, black ice, and freezing rain, creating treacherous driving conditions. On I-93, weather-related crashes spike during early morning hours when plowing is incomplete or visibility is poor.

Types of Catastrophic Injuries in Car Accidents on I-93

Traumatic Brain Injuries (TBI)

High-speed crashes on I-93 frequently result in traumatic brain injuries. TBIs range from concussions to severe brain damage and can cause lasting cognitive, emotional, and physical impairments. Victims may face memory loss, personality changes, and permanent disability.

Spinal Cord Injuries

Collisions, especially rear-end or rollover crashes, can fracture vertebrae or sever the spinal cord. These injuries may lead to partial or complete paralysis (paraplegia or quadriplegia) affecting mobility, sensation, and independence for life.

Amputations

Violent impacts with guardrails, heavy trucks, or secondary collisions can result in traumatic amputations. In some cases, limbs are surgically removed due to severe crush injuries or uncontrollable infections.

Severe Burns

Vehicle fires or chemical spills after a highway crash may cause third-degree burns. These injuries require multiple surgeries, skin grafts, and often lead to permanent disfigurement and psychological trauma.

Broken Bones

Victims may suffer multiple broken bones in the arms, legs, pelvis, or face. These injuries can limit mobility and function for extended periods, sometimes requiring reconstructive surgery and physical therapy.

Internal Organ Damage

Blunt force trauma can rupture the spleen, liver, or kidneys. Internal bleeding may not be immediately apparent but poses life-threatening risks. Victims should seek prompt medical care even if symptoms are not immediately apparent.

Wrongful Death

In the most tragic cases, high-speed or multi-vehicle collisions on I-93 lead to fatal injuries. Families may pursue wrongful death claims for the loss of a loved one due to another party’s negligence.

Legal Considerations for I-93 Accident Victims

Determining Fault in High-Traffic Areas

Accidents on I-93 may involve multiple vehicles, making it difficult to determine fault. Issues include:

Sudden stops due to congestion
Limited witness availability in high-speed zones
Disputed lane changes during merging

Dashcam footage, surveillance video from state highway and exit cameras, black box data, and police reports can be useful in reconstructing the circumstances of the crash to hold the involved negligent parties liable.

Choose an Experienced Massachusetts Car Accident Lawyer

For over 30 years, attorney John P. DiBartolo, Jr. has devoted his legal career to standing up for those injured in serious car accidents, including collisions on Massachusetts’s busiest highways like I-93. Having worked as a former liability claims adjuster, John understands how insurance companies attempt to minimize claims, delay payouts, or unfairly assign blame.

At the Law Offices of John P. DiBartolo, Jr., we fight to recover maximum compensation for your medical bills, lost wages, and pain and suffering. Our firm charges no hourly fees or retainers, and we only get paid if we win your case. With a commitment to personalized, powerful advocacy, we are here when you need us most.Attorney DiBartolo also serves on the Board of Governors for the Massachusetts Academy of Trial Attorneys, demonstrating his leadership and courtroom experience. To schedule your free consultation, call us at (413) 529-2955 or contact us online.