Fundamental Speed Limit

No matter what speed is posted, “reasonable and proper” is always the fundamental rule. On a highway posted 55 miles per hour, reasonable and proper may mean five miles per hour depending on conditions.

Chapter 90, Section 17¬†dictates the basic speed law, which 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.” Note “reasonable and proper”, for this is the fundamental speed law. No form of regulation, control, or restriction can supersede it.

Source: Procedures for Speed Zoning (MassDOT)