Speed management techniques encourage people to use safe speeds while driving. Managing vehicle speeds reduces the number and severity of collisions and increases the efficiency of traffic flow.
- Speed limits
- Speed policy
Speed management uses simple and effective solutions that encourage drivers to use appropriate, consistent speeds and plays a vital role in keeping roadways operating in a safe and efficient manner. The variance of driver speeds can cause stop-and-go traffic that leads to congestion, decreased traffic flow, and increased driver frustration.
Vehicle speeds have a significant impact on roadway safety. Speeding-related collisions result in more than 9,000 roadway deaths each year in the U.S., and many of these involve people that are walking or biking. Increased vehicle speed also increases the severity of the injuries that result from collisions. Speed management is important in work zone and construction areas as nearly 30 percent of fatal work zone crashes involve a speeding driver.
Agencies should develop consistent policies within their jurisdiction to encourage safe speeds. Once overall speed management policies are identified, agencies have a toolbox of strategies at their disposal to encourage desired speeds.
By designing a roadway to be self-enforcing, the roadway design will encourage vehicle speeds that are within the speed limit. This helps to reduce the number and severity of collisions related to speed. Self-enforcing road concepts use the road’s design, signing, striping, and other roadway elements to keep traffic moving at or below the desired speed limit. Examples include roundabouts that reinforce a 15-20 mph speed around the circle, and corridors with lane width reductions to encourage slower vehicle speeds.
Speed limits, advisory speeds, and special speed zones
Traffic engineers use the Manual on Uniform Traffic Control Devices—the industry standard for signing, striping, and traffic signals—as a guide for the effective placement of different types of speed-related signs.
- Regulatory speed limit signs indicate the legal limit allowed. These speed limits should be set through an engineering study.
- Advisory speed signs are usually black and yellow, and placed under warning signs, to provide drivers with a recommended safe speed. For example, an advisory speed sign placed under a Curve Warning sign tells the driver what the safe speed is for driving around the curve.
- School zone speed limit signs are designed to protect children as they travel to and from school by reducing the speed limit on roads near the school. These zones are often ‘activated’ at certain times of the day.
- Work zone speed limit signs reduce speed limits in work zones to protect road users and the vulnerable workers within it
Speed feedback signs
In areas where speeding drivers are a concern, some agencies have installed speed feedback systems. These signs identify the speed of an approaching vehicle and display a message like “Your Speed Is XX mph” (where XX is that driver’s actual speed) or “SLOW DOWN.”
Variable speed limits
Variable speed limit signs change the regulatory speed limit based on road, traffic, and weather conditions. They can improve both traffic flow and safety by restricting speeds during adverse conditions. On multi-lane highways, these systems can provide varying speed limits for each lane using overhead changeable message signs.
Agencies should work with state and local law enforcement to develop a comprehensive, data-driven program to enforce regulatory speeds. Enforcement coupled with public outreach is often the most effective, and both must be combined with properly-set speed limits and a strong speed management policy. Both face-to-face and automated photo speed enforcement can be effective in deterring speeding behavior.
When to use this strategy
Speed management makes sense for all roads. More aggressive strategies such as variable speed limits, speed feedback signs, and enforcement work best in areas with observed speeding issues and/or a history of speed-related collisions.
- Encourages appropriate and consistent speeds
- Matches roadway design and speed limits to drivers' expectations, making it more likely that the traveling public will comply
- Reduces congestion resulting from stop-and-go traffic
- Reduces number of collisions and injury severity when collisions do occur
What you need in order to implement
- A comprehensive speed management policy that addresses design, traffic operations, construction, maintenance, and law enforcement issues regarding speed.
- Identify long-range plans for bicycle lanes and pedestrian crossings that may require revised speed limits based on the needs of people walking and biking.
- Coordination among traffic engineers, roadway designers, traffic safety advocates, and law enforcement to identify speed-related safety and operational needs and solutions.
- Regulatory Speed Limit signs, advisory speed plaques for warning signs.
- Speed collection equipment like radar cameras and automated systems.
- Updates to speed studies on a regular basis to ensure that the posted speed limits are appropriate.
- Maintenance of the equipment that collects speed information.
Agency resources needs:
- Engineering staff with the knowledge and experience required to study and recommend appropriate speed limits, and to explain policy decisions to transportation partners and the public.
- Before-and-after speed studies to determine the speed impact of changes.
Learn more about this strategy
Manual on Uniform Traffic Control Devices (MUTCD), 2009 Edition (with Revisions 1 and 2).
Federal Highway Administration (FHWA), Speed Management Safety website.
Federal Highway Administration (FHWA), Self-Enforcing Roadways: A Guidance Report, FHWA-HRT-17-098, 2018 (PDF). https://www.fhwa.dot.gov/publications/research/safety/17098/17098.pdf
Federal Highway Administration (FHWA), Methods and Practices for Setting Speed Limits: An Informational Report, FHWA-SA-12-004, 2012. https://safety.fhwa.dot.gov/speedmgt/ref_mats/fhwasa12004/
National Highway Traffic Safety Administration, Speeding website.
(1) National Highway Traffic Safety Administration, Traffic Safety Facts, Speeding. DOT HS 812 480.
(2) Fatality Analysis Reporting System (FARS) 2017 Annual Report File, National Highway Traffic Safety Administration (NHTSA)
About key characteristics
Speed limits and speed-related safety and operations solutions are important on all roadway types in all locations.
Speed management strategies, like signing and pavement marking, are considered low-cost. More complex solutions often come at a higher cost, like roundabouts or law enforcement programs.
Technology ranges from low (standard speed limit and speed advisory signs) to high (variable speed limits and automated speed enforcement).
Setting speed limits, identifying speed-related operations and safety needs, and implementing speed strategies require collaboration among transportation planners, roadway designers, traffic engineers, and law enforcement.