FAQ: Speed Limits

Speeding and other traffic issues in a particular area can often prompt people to wonder if lowering the speed limit might be the right solution. 

Speed limits are determined by state law, as well as local and state ordinances. As outlined in N.C. General Statutes, the speed limit within city and town limits is 35 mph, unless otherwise determined by ordinance and posted. Outside of incorporated municipalities, the statutory speed limit is 55 mph, unless otherwise posted. 

The N.C. Department of Transportation has compiled a list of frequently asked questions and their answers to assist citizens in understanding how speed limits are established and what they can and cannot do to solve traffic concerns. Several FAQs are listed below and you may download NCDOT's brochure on speed limits for further information. 

From the N.C. Department of Transportation:

How are speed limits determined?

Roadways are initially designed to accommodate certain speeds. If a speed limit change is requested on a State Highway System road, a traffic engineer will perform an engineering and traffic investigation to determine the appropriate speed limit.

These investigations examine:

  • Road surface characteristics, shoulder conditions, roadway alignment and sight distance.
  • Commercial and residential development, and roadside friction (number of driveways, parking, pedestrians, etc.).
  • Safe speed for curves and other locations along the section of road being studied.
  • Frequency and severity of crashes.
  • 85th percentile speed — the speed at or below which 85 percent of the traffic is moving.

This investigation will help the traffic engineer determine if the speed limit is safe and reasonable. The traffic engineer will share the results of the investigation upon request. If a change is recommended, the traffic engineer will request approval from the State Traffic Engineer. Once approved, speed limit signs will be changed and the new speed limit will become legally enforceable.

Will lowering the posted speed limits reduce speeding?

Many people believe that lowering speed limits will reduce motorist speed. However, changing the speed limit is not always the best option. Speed limits are set at a limit that the roadway can safely accommodate by design, the majority of drivers will obey, and law enforcement can reasonably enforce.

Engineering studies have shown that there are often no significant changes in vehicle speeds following the posting of an artificially reduced speed limit. This information shows that most motorists drive at the speed they consider to be comfortable and safe. If motorists are regularly exceeding the posted speed limit through an area, enforcement is key to ensuring compliance. Lowering the speed limit by itself cannot guarantee motorists will obey the new regulation.

What if I have a speeding problem in my neighborhood?

Speeding on residential streets is a common complaint reported to the Department. If you believe motorists regularly exceed the speed limit along a particular road, contact your local law enforcement agency and make them aware of the concern. Police can check the speed of motorists and issue citations to offenders.

Neighborhood traffic often contributes to the problem. Programs such as community watch, neighborhood partnerships, and homeowner’s associations are often the most effective way to reach those drivers. The majority of speed offenders in neighborhoods are residents of that neighborhood and not motorists “cutting through.”

Common Misconceptions

It is often believed that stop signs, traffic signals and speed bumps will control vehicle speeds. While stop signs and traffic signals are important traffic control devices, they are not used to control vehicle speeds.

The purpose of stop signs and traffic signals is to assign right of way at intersections. Overuse of stop signs and traffic signals reduce both their effectiveness and driver compliance.

More on traffic control devices is available on the NCDOT website.