Unposted Speed Limits

Chapter 90, Section 17 also governs the speed of motor vehicles on unposted roadways.  The present unposted speed limits according to Chapter 90, Section 17 are condensed below:

….it shall be prima facie evidence of a rate of speed greater than is reasonable and proper if a motor vehicle is operated in excess of

  1. 50 miles per hour on a divided highway outside of a thickly settled or business district for a distance of 1/4 of a mile.
  2. 40 miles per hour on an undivided highway outside of a thickly settled or business district for a distance of 1/4 of a mile.
  3. 30 miles per hour in a thickly settled or business district for a distance of 1/8 of a mile.
  4. 20 miles per hour in a legally established school zone.

Note the distance requirements associated with the enforcement of Chapter 90, Section 17.  Instantaneous radar or laser readings are not adequate.  The motor vehicle must be shown to have been in excess of these speed limits for the entire distance associated with each respective speed limit.  Also the unposted speed limits cannot be posted, with the exception of a legally established school zone.

The definition of a “thickly settled or business district” is as follows: “The territory contiguous to any way which is built up with structures devoted to business, or the territory contiguous to any way where the 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.”

Source: Procedures for Speed Zoning (MassDOT)

If you’re interested in the leaning more about the history of Massachusetts unposted speed limits, Historic Speed Limits in Massachusetts (MIT) is a great place to start.