The primary goal of speed limits is safe and efficient traffic flow, so they should be set in the best interest of the motoring public’s right to use a roadway in a reasonable and proper manner. The ideal speed limit is both acceptable to the prudent driver and enforceable by our police. Massachusetts law requires that speed limit signs shall be posted only after an engineering and traffic investigation has been conducted in compliance with established traffic engineering practices. However, if a speed limit is posted without this procedure, it is considered illegal and unenforceable.