Evaluating the influence of flashing speed limit signs in school zones on driver behavior

Reduced-speed school zones can provide a safer and more walkable environment for children and young adolescents. Nevertheless, speed compliance remains an issue despite the inclusion of mitigation techniques such as signage and pavement markings. This poses a problem as there is a direct correlation between vehicle speed and the likelihood and severity of crashes. Traffic Control Devices such as School Speed Limit When Flashing Signs can help reduce this risk, but there is still an opportunity for improvement.

The objective of this study includes the use of a driving simulator to collect representative driver responses to Speed Limit Sign Beacons (SLSB) while considering the impacts on speed and yielding rates. A 20-mph SLSB was evaluated to closely resemble two roadways in Washington County, Oregon.

Yielding rates revealed that drivers stopped more frequently when the SLSB was on, and there was one child and one adult queued at the crosswalk. These findings aligned with the speed assessment, where the largest reduction was observed in this variable combination, resulting in statistically significant speed reductions of 2.87 to 2.91 mph. Additionally, speed after passing the SLSB revealed that the optimal location for this traffic control device relative to the crosswalk may differ based on roadway context. Higher-speed roads may require a larger distance to have adequate space to slow down, while lower-speed roadways may require a closer distance to increase driver attentiveness.

These findings expand the understanding of leveraging SLSB and the optimal placement to achieve safety improvements.