Driving Speed Limits and Rules

Basic Speed Rule and Maximum Limits

• A person driving must not exceed a speed that is reasonable and prudent given existing conditions and potential hazards.
• Speed must always be controlled to prevent collisions with people, vehicles, or other conveyances.
• If no hazards exist that require a lower speed, adhering to the specified speed limits is prima facie lawful.
• Exceeding the specified speed limit is considered prima facie evidence of unreasonable or imprudent speed and is unlawful.
• In a posted school zone, the speed limit is 10 mph below the usual posted limit for 45 minutes before and after school openings and closings.
• The speed limit is 30 mph in any business or urban residence district
• The speed limit is 35 mph in any rural residence district and on any class V highway outside the compact part of any city or town.
• The speed limit is 45 mph in any unimproved rural highway
• The speed limit is 55 mph in other locations, unless otherwise specified.
• A speed of 65 mph is permitted on the interstate system, the central New Hampshire turnpike, and the eastern New Hampshire turnpike where these highways are 4-lane divided highways or other divided highways of 4 or more lanes.
• A speed limit of 70 mph is set on I-93 from mile marker 45 to the Vermont border.
• On a portion of highway where road work is being done, the speed limit is reduced by at least 10 mph below the usual posted limit, which is displayed on signs.
• For vehicles with transponders, the limit is 25 mph through toll booths or gates equipped with transponder readers, except for open road tolling lanes, vehicles without automated tolling must stop.
• In open road tolling lanes, speed must be reasonable and prudent, not exceeding 65 mph.
• The 65 mph and 25 mph limits are the maximum lawful speeds, and exceeding them is prohibited.
• Prima facie speed limits can be altered as authorized.
• Drivers must reduce speed when approaching intersections, railway grade crossings, curves, hillcrests, narrow or winding roadways, and when special hazards exist due to weather or highway conditions.

Fines for Speeding

• Fines for exceeding speed limits in school zones, business/urban residence districts, rural residence districts, etc.:
  • 1-10 mph over: $50
  • 11-15 mph over: $75
  • 16-20 mph over: $100
  • 21-25 mph over: $200
  • 26+ mph over: $350
• Fines for exceeding the 65 mph limit:
  • 1-5 mph over: $65
  • 6-10 mph over: $100
  • 11-15 mph over: $150
  • 16-20 mph over: $250
  • 21+ mph over: $350
• Fines for exceeding the 70 mph limit:
  • 1-5 mph over: $65
  • 6-10 mph over: $100
  • 11-15 mph over: $200
  • 16-20 mph over: $300
  • 21+ mph over: $400
• All fines are subject to a penalty assessment.

Speed Limit Exceptions

• Speed limits do not apply to vehicles driven with due regard for safety:
  • Under the direction of peace officers during chases or apprehensions.
  • Fire department or fire patrol vehicles responding to a fire alarm.
  • Public or private ambulances or other emergency vehicles during emergencies.
• The exemption does not protect drivers from consequences of reckless disregard for the safety of others.

Minimum Speed Regulation

• Driving too slowly to impede normal traffic flow is prohibited, unless necessary for safe operation or compliance with law.
• A minimum speed limit of 45 mph is posted on the interstate highway system.
• The commissioner of transportation can set minimum speed limits if slow speeds consistently impede traffic flow.

Special Speed Limitations

• No person shall drive a motor-driven cycle at night faster than 35 mph unless equipped with headlights that can reveal a person or vehicle at 300 feet.
• Vehicles towing house trailers cannot exceed 45 mph.
• Vehicles with solid rubber or cushion tires cannot exceed 10 mph.
• The speed limit is restricted to what the specific bridge can handle safely, communicated via signage 100ft before each end of the structure.
• The commissioner of transportation will determine this maximum speed upon request from a local authority if they find the bridge cannot safely withstand vehicles traveling at otherwise permissible speeds.
• Proof of the commissioner's determination and the existence of signs is conclusive evidence of the maximum safe speed for the bridge.