
Quoting
RSA 265:60
II. Where no hazard exists that requires lower speed for compliance with RSA 265:60, I, the speed of any vehicle not in excess of the limit specified in this section or established as hereinafter authorized shall be prima facie lawful, but any speed in excess of the limit specified in this section or established as hereinafter authorized shall be prima facie evidence that the speed is not reasonable or prudent and that it is unlawful:
(a) In a posted school zone, at a speed of 10 miles per hour below the usual posted limit from 45 minutes prior to each school opening until each school opening and from each school closing until 45 minutes after each school closing.
(b) 30 miles per hour in any business or urban residence district as defined in RSA 259:118;
(c) 35 miles per hour in any rural residence district as defined in RSA 259:93, and on any class V highway outside the compact part of any city or town as defined in RSA 229:5, IV;
(d) 55 miles per hour in other locations, except as provided in (e);
(e) 65 miles an hour on the interstate system, the central New Hampshire turnpike and the eastern New Hampshire turnpike in locations where said highways are 4-lane divided highways or other divided highways of 4 or more lanes.
(f) On a portion of a highway where officers or employees of the agency having jurisdiction of the same, or any contractor of the agency or their employees, are at work on the roadway or so close thereto as to be endangered by passing traffic, at a speed of 10 miles per hour below the usual posted limit, but in no case greater than 45 miles per hour. The speed shall be displayed on signs as required by RSA 265:6-a.