Speed limits in Massachusetts are different than in most of the rest of the country, according to documents from the state’s department of transportation (MassDOT) Highway Division.
Several Massachusetts General Laws govern speed limits on all streets and highways throughout the Commonwealth, with the exception of the Massachusetts Turnpike.
Uniquely, the basic premise under Massachusetts law is: “No person operating a motor vehicle on any way shall run it at a rate of speed greater than is reasonable and proper, having regard to traffic and the use of the way and the safety of the public.”
This is important, they say, as no regulation supersedes it. A road may be legally posted for 30 mph, but weather conditions, traffic, construction or other hazards may mean the “reasonable and proper” limit is lower than the posted limit.
An easy phrase to remember is that speed limits are for the, “daytime, conditions permitting.”
Under proper conditions, limits can be split into two categories: posted or regulatory speed limits and statutory speed limits which are unposted.
Statutory speed limits exist in the absence of special speed regulations (which are simply posted speed limits). With the exception of school zones, if a special speed regulation exists it will supersede the statutory speed limit, according to MassDOT.
But, “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 50 mph on a divided highway outside of a thickly settled or business district for at least 1⁄4 of a mile, 40 mph on an undivided highway outside of a thickly settled or business district for at least 1⁄4 of a mile, 30 mph in a thickly settled or business district for at least 1⁄8 of a mile and 20 mph in a legally established school zone.”
A regulatory speed limit is one that has completed a traffic engineering study, has a special speed regulation that has been signed by the road’s owner, the Registry of Motor Vehicles, the MassDOT Traffic and Safety Engineering Section and has the appropriate signage erected to clearly define the special speed zones. If this procedure is not followed, the speed limit is in violation of the law and is considered unenforceable, says MassDOT.
The traffic engineering studies that set special speed regulations consider the speed that drivers actually are traveling. Curiously enough, there is an assumption that most drivers are “prudent and capable of selecting safe speeds.”
After completing a speed study, considering crash data and historical conditions in that area, the observed 85th percentile speed, which is “a measured value of prevailing speeds at which 85 percent of all vehicles are traveling at or below in free-flowing traffic” is the basis for establishing a limit.
After the 85th percentile speed has been calculated, the value is rounded to the nearest multiple of five to determine the limit. With few exceptions, this is the speed limit that is set.
Should a municipality wish to challenge a speed limit on a municipal roadway, they can do a speed study at their own expense, and even then MassDOT does not guarantee a change in the limit, according to the Plympton Highway Surveyor, Scott Ripley.
In Halifax, voters recently turned down a Special Town Meeting article to set a fundamental speed limit across the town, so that it would be lower than the statutory speed limit, an option that is being explored by Plympton officials who are concerned about the state raising speed limits there.