Auto Accident Risks Dramatically Increased by Urban Advertising: Study

Researchers suggest improved legislation for regulating illuminated roadside signs to help enhance driver safety.

A new study indicates that highly illuminated and dynamic advertising displays in urban areas can significantly increase the risk of auto accidents, especially during nighttime driving.

In findings published in the journal Acta Polytechnica CTU Proceedings on June 12, researchers from the Czech Technical University in Prague conducted a study analyzing how the brightness and dynamic elements of advertising displays affect driver attention, reaction times and the overall ability to perceive traffic situations.

Illuminated advertising, especially at night, attracts drivers’ attention and can be distracting. The brightness and contrast of these ads, compared to road lighting, can significantly impact visual field perception and increase the risk of road accidents.

In the new study, the research team measured light parameters of advertising displays in comparison to public lighting, using horizontal roadway illumination and gradient illuminance analysis.

The team, led by Luboš Nouzovský, found that advertisements, particularly those with bright and dynamic content, can negatively impact road safety by distracting drivers, leading to longer reaction times and an increased risk of accidents.

To evaluate the risks, the researchers conducted field measurements in Prague using two methods: horizontal illuminance readings and a gradient luminance analysis. These techniques revealed how illuminated advertising competes visually with road lighting and disrupts driver perception.

Although most signs did not significantly alter roadway brightness, the study found that some high-brightness billboards produced luminance levels more than 12 times greater than nearby public lighting, particularly at night. This was observed at one location (D5), where the excessive brightness dramatically outshone the road surface and created a veiling effect that impaired a driver’s ability to detect low-contrast objects like pedestrians or traffic markings.

The study also highlighted two key physiological risks:

• Adaptive brightness: When drivers are exposed to extremely bright advertising displays, their eyes adjust to that intensity, reducing their ability to see darker areas of the road ahead.
• Peripheral distraction reflex: Dynamic signs with changing images or motion can trigger reflexive attention shifts away from the road, a phenomenon described as a “hazard response.”

Even though the tested advertisements did not technically violate current lighting standards, the researchers emphasized that no existing regulations account for dynamic or time-varying brightness, which makes such signage especially hazardous.

The authors concluded that these displays cannot be treated like standard lighting systems, as they serve no functional safety purpose and are not optically optimized for the roadway. Instead, they act as sources of distracting glare, with no identified benefits to driver performance or traffic safety.

The researchers called for updated legislation to regulate both static and dynamic ads, recommending limits on brightness, motion and placement. They also suggested modifying light sources to reduce glare and improve driver visibility.

Roadside Advertising and Driver Safety

In addition to the new findings, researchers in Australia and the Netherlands conducted a study last year, examining the effect of roadside advertisements on accident risk.

The international study found that the impact of these distractions varies depending on the driver’s experience, age and proximity of the distraction to the road.

Researchers recommended implementing appropriate signage and road markings before construction zones, as well as designing signs that accommodate drivers of all ages by considering factors such as word count, font size and overall sign dimensions.