Why Radar Speed Signs Work

The Science Behind Radar Speed Signs’ Ability to Change Driver Behavior

Radar speed signs operate on the principle of Feedback Loops, a concept that has proven effective in influencing behavioral changes. This approach involves providing individuals with real-time information about their actions and giving them an opportunity to modify those actions, thereby encouraging improved behaviors. This concept, highlighted by WIRED in June 2011, forms the basis for understanding why radar speed signs work and their profound impact on driver behavior.

“Provide people with information about their actions in real time (or something close to it), then give them an opportunity to change those actions, pushing them toward better behaviors. Action, information, reaction.” (Source: WIRED, June 2011)

Why do radar speed signs work?

Why radar speed signs work and why they can have a profound effect on driver behavior.

Familiarity breeds inattention” says RoadtripAmerica.com, citing inattentive drivers as the most common source of collisions. The behavior, described as “driving on autopilot” or “highway hypnosis,” is the focus of a Churchill Insurance study of drivers’ habits that reveals: On average, drivers make eight journeys on familiar routes each week. And, while traveling on these familiar routes, 46% of drivers say they are most likely to have no recollection of how they got to their destination.

The study – which identifies the top “autopilot journeys” as the work commute (43%), going shopping (16%) and motorway driving (15%) – also confirms that autopilot drivers regularly break the speed limit (25%), brake too late and don’t stop at pedestrian crossings because they haven’t seen them until it’s too late. Further, 7% of motorists say they are most likely to switch to autopilot while “doing the school run” – a zone that is especially vulnerable to speeding dangers.

Understanding how the brain works can explain the findings and help identify solutions to improve traffic safety. At its basic level, the human brain – as an electrochemical organ – produces three types of brain waves that have an impact on driver behavior, each reflecting specific levels of the awake brain:

  • Beta waves reflect a strongly engaged mind, active in conversation or debate.
  • Alpha waves reflect a state of rest or relaxation (e.g. a break from work to take a walk in a garden).
  • Theta waves reflect a state of functional daydream – the ability to complete repetitious or habitual tasks, such as driving to and from work.

Shifting a driver from a Theta “autopilot” state to a Beta “engaged” state requires a trigger, identified by the Reticular Activator (RA), responsible for categorizing sensory input. The RA is the ignition part of the brain, on alertsearching and categorizing all sensory input into categories such as familiar/connected, unusual/shocking/strange, or dangerous/threatening/problematic. Once the RA — which also controls the transition between different states — is triggered by something unfamiliar, problematic or dangerous, the brain instantly converts from Theta to Beta.


Radar Speed Signs as Reticular Activators

Strategically placed radar speed signs act as triggers, stimulating the RA to identify potential dangers and prompting the transition from Theta to Beta. Integrated into comprehensive traffic management plans, particularly in areas with familiar routes and a high risk of pedestrian traffic, radar speed signs effectively alert drivers to pay attention. In Theta mode, drivers may perceive speed limit signs as usual and familiar, but the introduction of something unusual and problematic, such as a flashing radar speed sign indicating high speed, prompts a shift to Beta mode. This engagement makes drivers more alert, leading to reduced speeds and safer driving practices.

Radar Speed Signs act as Reticular Activators

An independent speed study conducted by the City of Bellevue (WA) Transportation Department found that at ten locations — where radar driver feedback signs had been installed for six or more years — the speed reduction effectiveness continued to increase over time: 60% of drivers reduced speed by 10 mph.

Radarsign data from various locations, such as Alpharetta, GA, demonstrated a consistent five mph reduction in average speeds and a remarkable 62% reduction in drivers exceeding speed limits by more than five mph, indicating a sustained positive shift in driver behavior more than two years after installation. (Alpharetta, GA location — comparing week 1 data with week 109 data).