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Traffic Engineering

Frequently Asked Questions on Speed Limits


Q1. What are the laws and regulations that govern speed limits in Massachusetts?

A1. Section 17 and Section 18 of Chapter 90 of the Massachusetts General Laws (MGL c. 90 §§ 17 and 18) dictates the requirements for establishing posted speed limits and the statutory speed limits on all other streets and highways. In addition, MassDOT and all municipalities are required by MGL c. 85 § 2 to follow the standards stated Manual on Uniform Traffic Control Devices (MUTCD) for the posting of speed limit signage.

Q2. What is a regulatory speed limit?

A2. With certain exceptions noted below, a regulatory speed limit is one that has a Special Speed Regulation and speed limit signs posted per MGL c. 90 § 18. A special speed regulation is established by conducting an engineering study, having the authority responsible for legislating municipal traffic code approve the proposed speed zones (city- and town-owned ways, only), submitting the study and proposed speed zones to MassDOT, having a special speed regulation duly approved by the MassDOT Traffic and Safety Engineering Section and the Registry of Motor Vehicles, and, lastly, erecting standard speed limit signage

The Section 2B.13 of the MUTCD also states that, "Speed zones (other than statutory speed limits) shall only be established on the basis of an engineering study that has been performed in accordance with traffic engineering practices. The engineering study shall include an analysis of the current speed distribution of free-flowing vehicles." To comply with this statement, MassDOT has established Procedures for Speed Zoning, where all of the details for the required engineering study may be found.

Q3. How does a municipality create a Special Speed Regulation on a city- or town-owned way?

A3. Full details on the procedure for creating Special Speed Regulations may be found in the MassDOT Procedures for Speed Zoning. The following is a summary of the process:

  1. Request sent by city/town to MassDOT District Office.
  2. MassDOT will meet with city/town for detailed explanation of procedures (if requested).
  3. City/town will submit proposed speed zones along with engineering justification and backup data.
  4. Submittal reviewed by MassDOT District Office and Traffic & Safety Engineering Section.
  5. If approved by MassDOT, special speed regulation prepared by MassDOT Traffic & Safety Engineering Section.
  6. Regulation approved by city/town body that governs the municipal traffic code.
  7. MassDOT Traffic & Safety Engineering Section and Registry of Motor Vehicles signs off on approved regulation.
  8. Speed limit signs are erected by city/town. Speed limit is now enforceable.

Q4. What is a statutory speed limit?

A4. Statutory speed limits exist in the absence of special speed regulations and official posted speed limits. MGL c. 90 § 17 requires that drivers operate motor vehicles at a rate of speed that is no greater than reasonable and proper with regard to the use of the road and safety of the public. Reasonable and proper speeds are defined as:

  • 20 mph in a school zone;
  • 30 mph in thickly settled or business district for at least 1/8 of a mile;
  • 40 mph on an undivided way outside of a thickly settled or business district for at least 1/4 of a mile; and
  • 50 mph on a divided way outside of a thickly settled or business district for at least 1/4 of a mile.

Section 2B.13 of the MUTCD does not require an engineering study to establish a statutory speed limit since they are set based upon geographic criteria in the absence of a speed regulation. However, with the exception to the types noted in Question 8, statutory speed limits do not include posted signs.

Q5. What is a thickly settled or business district?

A5. MGL c. 90 § 1 of the MGL defines a thickly settled or business district as, "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."

Q6. How does the new speed limit legislation passed in 2016 affect my town?

A6. Sections 193 and 194 of Chapter 218 of the Acts of 2016 creates two new sections to Chapter 90 of the MGL:

  • Section 193 allows the municipality to opt-in to MGL c. 90 § 17C, 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.
  • Section 194 creates MGL c. 90 § 18B, allowing municipalities to establish regulatory 20 mph safety zones. Since this creates a regulatory speed limit, the MUTCD requires an engineering study prior to the establishment of the the safety zone and it should conform to the guidance found in the MassDOT Procedures for Speed Zoning.

Q7. If a city or town opts-in to Section 193 of Chapter 218 of the Acts of 2016, will that supersede any existing posted speed limit?

A7. No. This legislation only affects streets that are currently governed by a statutory speed limit. If an existing special speed regulation is in place, it will continue to govern.

Q8. Can cities and towns post their own speed limits?

A8. Standard speed limit signs may only be posted upon the establishment of a regulatory speed limit per MGL c. 90 § 18 and the MassDOT Procedures for Speed Zoning. However, there are other speed-related signs that cities and towns may elect to post upon completion of proper engineering studies:

  • Municipalities that opt-in to Section 193 of Chapter 218 of the Acts of 2016 on a city- or town-wide basis may post Thickly Settled Speed Limit 25 Unless Otherwise Posted (MassDOT code MA-R2-9A or MA-R2-9B) signs at jurisdictional boundaries. Please note that these signs cannot be placed on State Highway without prior approval from MassDOT. MassDOT also recommends that, if a city or town is considering opting-in to this legislation, it is done so for the entire municipality to avoid potential confusion for drivers.
  • Municipalities that opt-in to Section 193 of Chapter 218 of the Acts of 2016 on a street-by-street basis may post Thickly Settled District 25 MPH (MassDOT code MA-W13-4) signs at the upstream ends of street.
  • School Zone speed limits may be posted if established under the standards of the MA Amendments to the MUTCD.
  • Safety Zone speed limits may be posted and should follow MassDOT guidelines, as described in Q9.

Q9. What is the process for establishing Safety Zone speed limits?

Safety Zone speed limits are the only regulatory speed limits that municipalities can adopt without prior approval from MassDOT. Safety Zones cannot, however, be placed on State Highway without MassDOT approval.

Speed limits within a Safety Zone must be set at 20 mph and are intended to be used in areas where vulnerable road users are likely to be present. Examples of such areas are: parks and playgrounds, senior citizen housing and centers, hospitals or other medical facilities, high schools and higher education centers, and daycare facilities. Note that Safety Zones should not be used in place of School Zones for streets adjacent to grades 1-8 schools.

To establish a Safety Zone, MassDOT has developed the following minimum criteria:

  • The street should be adjacent to a land use that is likely to attract 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 1/4 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.

Regulatory speed limit signs are required to conform to the MUTCD, per MGL c. 85 § 2. Therefore, an engineering study must be performed to validate the posting of signage. The engineering study shall include an analysis of the current speed distribution of free-flowing vehicles.

In an area where a legal Special Speed Regulation has been enacted, the Safety Zone should be terminated with a Speed Limit (MUTCD code R2-1) sign that corresponds to the regulatory limit shown in the regulation. If the Safety Zone is in an area that has no Special Speed Regulation, it should be terminated with an End Speed Zone (MassDOT code MA-R2-7) sign.

Cities and towns are also responsible for modifying their Municipal Traffic Code to reflect the locations of all Safety Zones prior to the posting any signage.

Q10. Can speed limits be added or modified on city or town ways that have been constructed or reconstructed through a Federal Aid Project?

A10. All Federal Aid Projects in Massachusetts should have an executed Traffic Control Agreement signed between the municipality and MassDOT. The Traffic Control Agreement requires the city or town to maintain all traffic control devices, including signage, in accordance to the approved plans for that project. Any modifications, including the addition of new signage, must be approved in advance by MassDOT. To request a modification to a Traffic Control Agreement, please contact:

Massachusetts Department of Transportation
Highway Division - Traffic & Safety Engineering
Attention: Regulations Engineer
10 Park Plaza, Room 7210
Boston, MA 02116

Q11. Are design drawings available for fabricating speed limit signs?

A11. MassDOT has created the following sign face drawings:

Other MassDOT standard sign designs may be found on the Traffic & Safety Engineering's Signs page. All other sign designs may be found in FHWA's Standard Highway Signs and Markings book.


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