About the role of speed limits

Learn about setting speed limits and the role that they play in speed management.

Table of Contents

About the role of speed limits on Massachusetts roadways for speed management

Setting speed limits is an element of speed management. To effectively reduce vehicle speeds, setting speed limits should be included as a part of a broader strategy that includes design changes to the road and other educational components. Often MassDOT is asked to address speed related concerns by simply changing speed limit signs. Research and experience, though, have taught us that changing posted speed limits alone does not typically change the way people drive – at least not by itself. Speed limit reductions on high speed and high crash streets are most effective when coupled with the kinds of physical engineering changes described in Roadway Treatment Toolkit.

When exploring speed limit changes, the first step is to collect information and establish a target speed. Visit the speed management home page for detailed information on establishing a target speed. MassDOT's end goal is that roadways are self-enforcing, meaning that based on the roadway design and speed management tools implemented, drivers will not go faster than the appropriate speed, making the roadway safe and comfortable for everyone of all modes, ages and abilities.

Residents interested in speed limit changes should contact their municipal government. There are two main categories of speed limits that govern Massachusetts roadways:

  • Regulatory speed limits, also known as Special Speed Regulations. These speed limits are based on speed studies conducted by MassDOT or the municipality on roadways governed by MassDOT's Speed Zoning Procedures. These speed limits are the only ones that can be signed with white regulatory speed limit signs. It is also possible to rescind a special speed regulation through a written request to MassDOT to make a roadway a statutory speed limit (more information below). The speed zoning process to modify or create a new Special Speed Regulation results in a recommended speed limit that is enforceable. MassDOT does not simply rely on the 85th percentile to determine a recommended speed limit. Many factors are considered in the final recommendation, including adjacent land use, expected road users, and safety history. Municipalities have the option to not adopt the regulatory speed limit and instead use the information to implement speed management to achieve a target speed.
  • Statutory speed limits. These speed limits are established by legislation, when there are no Special Speed Regulations governing a roadway. Statutory limits are based on the idea that certain similar categories of roadways can operate safely at certain maximum speeds under ideal conditions, and do not have a speed limit sign posted with them, with some area-wide exceptions. Statutory speed limits according to Mass General Law – Part I, Title XIV, Chapter 90, Section 17 are:
    • 50 mph for a distance of one quarter mile on a divided highway outside of a thickly settled* or business district
    • 40 mph for a distance of one quarter mile on any way outside of a thickly settled* or business district
    • 30 mph for a distance of one eighth mile in a thickly settled* or business district
      • 25 mph if municipality has opted into Section 17C
    • 20 mph at any point in a school or safety zone

*A thickly settled or business district is "the territory contiguous to any way which is built up with structures devoted to business, or the territory contiguous to any way where dwelling houses are situated at such distances as will average less than two hundred feet between them for a distance of a quarter of a mile or over."

Note on Statutory Speed Limits: A vehicle must exceed the speed limit designated in the respective category for the entirety of the stated distance in order to be in violation Ch 90 Section 17.

Establishing safety zones, school zones, and changing the default speed limit to 25 mph

The following are tools to lower speed limits that work well when combined with roadway design changes communication, and enforcement. Visit the MassDOT roadway treatment technical toolkit for more.

MGL Ch90s17C: Thickly Settled and Business District Speed limit Reduction

In 2016, legislation was passed allowing a municipality to opt-in to Section 17C of Chapter 90 of the MGL, thereby reducing the statutory speed limit from 30 mph to 25 mph on any or all city- or town-owned roadways within a thickly settled* or business district. The legislation also requires cities and towns to notify MassDOT of these changes. For more information on the list of municipalities that have notified MassDOT of opt-in for Ch90s17C.

Safety zones

Safety zones are specially designated areas such as parks, playgrounds, senior citizen housing, hospitals, and childcare centers. Within these zones, speed limits must be set at 20 mph. Safety zone speed limits are the only regulatory speed limits that municipalities can adopt on city- and town-owned ways without approval from MassDOT; they cannot be placed on state highways without prior written approval by MassDOT. Safety zones should have roadway treatments that cue drivers to slow down.

Where do safety zones apply?

  • The street should be adjacent to a land use that is likely to be an origin or destination for vulnerable road users.
  • The safety zone should contain one or more areas that have potential conflicts between motor vehicles and vulnerable road users that warrant a reduction in speeds such as crosswalks, driveways, or side streets.
  • The minimum length of the safety zone should be at least ¼ of a mile and it should not extend more than 500' beyond a side street unless an applicable land use continues along the adjacent block.

Learn more about safety zones in Chapter 10.c of the Procedures for Speed Zoning on State Highways and Municipal Roads

School zones

Similar to safety zones, school zones are specially designated areas around schools where, once established, the speed limit must be set at 20 mph. The limit is only in effect, however, during specific times.

Where do school zones apply?

  • At a public, private, charter, or vocational technical school recognized by the Massachusetts Department of Elementary and Secondary Education and serves one or more grades between K and 12.
  • Students walk or bicycle to or from the school and are expected to cross or enter the roadway where the school zone is proposed; or the school and related facilities (e.g., classrooms, cafeteria, gymnasium, playground, athletic fields, parking lots) are separated by the roadway and require the students to cross the roadway on foot to access the facilities.
  • Learn more about school zone criteria in the MassDOT Speed Zoning Procedures and in Part 7 of the 2022 Massachusetts Amendments to the MUTCD (Manual on Uniform Traffic Control Devices)

How Regulatory Speed Limits can be Changed

There are currently two ways to change Regulatory Speed Limits in Massachusetts: rescinding a Special Speed Regulation or requesting/conducting a speed study to modify or add a Special Speed Regulation. The process for changing a Regulatory Speed Limit can depend on the jurisdiction of the roadway in question (which entity owns and operates it). The MassDOT Road Inventory Interactive Map can be used as a means to help identify the jurisdictional ownership of roadways in Massachusetts.

Rescinding a Special Speed Regulation on roadways under municipal jurisdiction

Cities and towns may rescind Special Speed Regulations on roads under their jurisdiction. A written request must be sent into MassDOT Highway's Traffic and Safety Engineering Department with the limits of each road where the special speed regulation is to be removed. Written request should include the roadway name and coordinates to note start/end limits. The request does not require a speed study. When approval is granted, the city/town must remove all speed limit signs associated with the rescinded regulations and erect any necessary signs where applicable. At this point the roadways will be governed by the municipally accepted statutory speed limits.

Changing a Special Speed Regulation on state routes under MassDOT jurisdiction

A municipal official can request a speed limit be modified on a roadway within their municipal boundary under MassDOT jurisdiction. Once a written request is received by MassDOT Highway’s Traffic and Safety Engineering Department, MassDOT will have 90 days to respond with an approval or denial to the request. These requests do not require a speed study, but justification for the request can help MassDOT with its evaluation. As a policy, Special Speed Regulations on roads under MassDOT jurisdiction are not modified unless a speed study appropriately justifies the change.

Establishing a new Special Speed Regulation

If the thickly settled, school zone, or safety zone does not apply, and if you are not rescinding a special speed regulation to be a statutory speed limit, here is how Special Speed Regulations are set in broad strokes:

  • Step 1: Municipalities request a speed limit review from MassDOT. There are many reasons why a request can be submitted: changing traffic patterns or adjacent land uses, feedback from the public, roadway design changes, interest in making a roadway safer for vulnerable road users, etc. Only municipalities, can request a speed limit review from MassDOT, residents should contact their municipal government.
  • Step 2: MassDOT or the municipality conducts a speed study. Engineers monitor the location to assess current traffic patterns, existing driving speeds, and factors that impact safety of all roadway users.
  • Step 3: MassDOT or the municipality recommends a speed limit. *If the study shows speeds are not reasonable for one reason or another, MassDOT and the municipality should utilize speed management tools and then revisit the speed zoning process once safer speeds are achieved.
  • Step 4: Municipal officials accept the recommendation, it is signed by MassDOT, and at that point it is an official regulation. Only then can new signs be installed, and the speed limit may be enforced. MassDOT cannot enforce speed limits.

MassDOT's goal is that roadways are self-enforcing, this means the roadway design and speed management tools implemented will encourage drivers to travel at appropriate speeds, making the roadway safe and comfortable for everyone – people driving, walking, biking, using other mobility devices.

Take action

  1. Public: Reach out to municipal government to voice concerns and share speed management information.
  2. Municipalities: Work closely with members of the public and MassDOT to define areas where roadway safety can be improved. Additionally, municipalities initiate and implement speed management roadway treatments and speed zoning studies.
  3. MassDOT: Work closely with municipalities to help them conduct speed studies and implement speed management. MassDOT also signs official speed limits into law.

Learn more

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