A common misconception is that lowering speed limits alone may have little practical effect on driving behaviors for motorists. Most drivers choose a travel speed they feel comfortable with in relation to the conditions present, regardless of what speed is posted. To encourage safe travel speeds, a broader strategy should be implemented, including geometric changes that will encourage slower operating speeds, education, and enforcement components.
Unrealistically low speed limits could lead to more crashes by promoting two distinct groups of drivers: Those attempting to observe the speed limit, and those driving at what they feel is reasonable and prudent. Increased uniformity in vehicle speeds will decrease crashes by reducing the likelihood of tailgating, improper passing, and other forms of reckless driving.
Types and uses of common speed limit and advisory speed signs
There are several different types of regulatory and advisory speed signs that are used throughout Massachusetts.
Regulatory Speed Limits: Speed limits that have a special speed regulation and has been established in accordance with the Massachusetts General Laws (MGL) c.90§18 and the MassDOT Procedures for Speed Zoning.
Municipalities can request a speed regulation in coordination with the MassDOT Highway District Office. Further information can be found on the Request speed zoning page.
Statutory Speed Limits: Speed limits for roads that do not have posted speed limits and have been established by MGL c.90§17 to apply throughout the Commonwealth. These include:
- 50 mph on a divided highway outside of a thickly settled or business district for at least ¼ of a mile
- 40 mph on an undivided highway outside of a thickly settled or business district for at least ¼ of a mile
- 30 mph in a Thickly Settled or Business District for at least 1/8 of a mile. A Thickly Settled or Business District is identified as an area where homes are less than 200 feet apart or areas where businesses are built up, for a distance of ¼ mile. Where municipalities have adopted MGL c.90§17c, the speed limit is further reduced to 25 mph. Further information can be found on the Notify MassDOT of Chapter 90 Section 17c adoption page.
- 20 mph in a legally established school zone
*Please note that statutory speed limits only exist in the absence of special speed regulations. If a special speed regulation exists, that posted speed limit will always supersede a statutory speed limit within a thickly settled or business district.
Advisory Speed Limits: Speed limits that are recommended safe driving speeds to alert drivers of the maximum recommended speed through a curve, a winding road, or for other special road conditions. Advisory speeds are not enforceable since their intent is to advise motorists of an appropriate speed, not regulate it.
Work Zone Speed Limits: Speed limits within construction work zones are set to improve traffic flow and improve safety for motorists and construction personnel. Reduced speed limits are based on conditions such as lane closures, narrow lanes, unexpected changes to geometry, and other potential hazards. Speeding violations in work zones are subject to double fines.
School Zone Speed Limits: Speed limits within a school zone are established for the protection of students walking to and from school.