Speed limits should promote safe travel and be perceived by the public as safe and reasonable.  Providing appropriate speed limits is the first step towards voluntary compliance and the cornerstone for effective speed management.

Key Actions:

• Develop a computer-based expert speed zone advisor for setting credible, safe, and consistent speed limits.  (In progress)

• Determine the frequency -- the distance between signs -- at which to post speed limits signs. 
  (Planned, 1 year)

• Develop guidance for conducting engineering studies used to set speed limits.  (Planned, 3 years)

The road design process often results in speeds higher than intended, which creates undue risks for non-motorists and frustrates motorists who perceive posted speed limits as artificially low.  Identifying methods  to achieve desired speeds in the design process will ensure safer operating speeds compatible with road function and reduce the demands on law enforcement.

Key Actions:

• Research roadway design factors that influence driver speed selection and speed prediction models that can be used in the design process to achieve appropriate travel speeds.  (In progress)

• Research and demonstrate methods to achieve appropriate traffic speeds on main roads through towns and other areas not suitable for traditional traffic calming techniques.  (Planned, 1 year)

• Identify traffic calming techniques for reducing speed in pedestrian activity areas.  (Planned, 1 year)

• Develop guidelines for designing new roads and retrofitting existing roads to achieve appropriate travel speeds.  (Planned, 3 years)

Run-off-road crashes at curves are primarily due to speed.  Consistently relaying appropriate curve speeds to motorists will reduce the frequency of run-off-road curve crashes.

Key Actions:

• Research and evaluate low-cost driver perceptual countermeasures to reduce speeds. 
  (In progress)

• Test and evaluate speed activated roadside displays that warn drivers that are exceeding safe speeds based on curve geometry, pavement friction, and vehicle characteristics.  (Planned, 3 years)

• Develop and evaluate cooperative infrastructure-vehicle systems that alert drivers or adapt speed when traveling too fast for conditions.  (Planned, 3 years)

Variable speed limits are speed limits that change relative to road, traffic, and environmental conditions.  Over 450,000 injury crashes and nearly 6,500 fatal crashes occur annually during adverse road conditions.  Speeding is estimated to be a factor in over 50 percent of these crashes.

Key Actions:

• Promote the use of VSL in work zones to increase motorists’ compliance and improve worker safety.  (Planned, 1 year)

• Test and evaluate the effectiveness of VSL from a safety and traffic efficiency perspective on busy urban freeways and rural interstate corridors with adverse weather conditions.  (Planned, 3 years)

• Evaluate VSL applications in combination with automated speed enforcement systems.  (Planned, 3 years)

Vehicle safety systems and communications technologies, such as adaptive cruise control, vehicle speed limit sensing and feedback, driver control speed limitors, wireless roadside beacons, vehicle infrastructure integrated safety systems and stability control systems are rapidly evolving and provide opportunities to alert or prevent drivers from exceeding safe speeds.

Key Actions:

• Evaluate the effectiveness of onboard vehicle technologies for controlling unsafe speeds for conditions.  (In progress)

• Promote the use of effective onboard vehicle technologies to achieve safe travel speeds.  (Planned, 1 year)

• Research appropriate techniques such as adaptive cruise control, vehicle speed limit sensing and feedback, driver control speed limitors, wireless roadside beacons, vehicle infrastructure integrated safety systems and stability control systems for adapting vehicle speed to the posted speed limit.  (Planned, 3 years)

• Field test and evaluate adaptive speed control in combination with variable speed limits.  (Planned, 3 years)