Speed management

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.

Self-enforcing roadways

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.

Speed enforcement

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.