Long-Term Effectiveness of Radar Speed Display Boards in School Zones

Author(s): Eric D. Hildebrand, Daniel D. Mason, Denis P. Paradis, Kaitlin E. Hazzard

Slidedeck Presentation:

7B Hildebrand_The Long-term Effectiveness of Speed Display Boards used in School Zones


Speed display boards are a relatively new speed reduction technique used in Canada. They
use radar technology to display in real-time the speed of oncoming drivers through transition
zones to encourage them to slow down to the posted limit. Previous studies have evaluated
their effectiveness with simple before-and-after analyses for relatively short time periods. This
paper evaluates the long-term effectiveness of speed display boards on speed reduction
through school zones. Traffic speed surveys were performed prior to the installation of speed
display boards at two selected school zones as well as one week, two months, one year, and
nearly four years after the boards were activated. The intent was to document the ‘novelty’
effect, if any, that would result in diminished effectiveness over time. Results including mean
speeds, 85th percentile speeds and speed variances were analyzed using statistical methods.
Results show a sustained and statistically significant reduction in the average speeds ranging
from 5-14 km/h dependent mostly on the degree of excessive speeding prior installation but also
on the location within the school zone. Mean speeds where reduced consistently to a level of
approximately 36-37 km/h (in a 30 km/h posted zone). The variances in speed observations
showed no statistically significant changes. It was concluded that speed display boards have a
statistically significant long-term effect on reducing motorist speeds through school zones