In a joint project with the City of Sandy Springs in Georgia, Applied Information has deployed a dual radar system to help slow traffic around schools in the interest of safety for schoolchildren. Radar signs operate in conjunction with school beacons to reduce the speed of vehicles as they approach. At first, the forward-facing radar that controls the electronic sign in the beacon was used to this effect, but although initial results showed the vehicles did slow down slightly when the beacon signs were on, the effect was not as significant as expected. Further observation showed that vehicles did slow down in response to the school beacons and radar signs, but this only occurred after the sign, where the change in speed couldn’t be recorded. With this new information, we added a second radar in the school zone to measure the speed of vehicles after they had passed the sign.
After this upgrade, an analysis of the data from the Powers Ferry Heards WB beacon from 11:00am on Monday, May 23rd until midnight on Thursday, May 26th showed the following:
Median Speed Beacon ON: 33.9 MPH
85th Percentile Speed Beacon ON: 40.6 MPH
Median Speed Beacon OFF: 41.2 MPH (+22%)
85th Percentile Speed Beacon OFF: 45.9 MPH (+13%)
The median speeds are weighted by volume. Vehicle speed registered at night, when traffic volumes are low, factor less into the median than vehicle speed during the morning and evening, when more vehicles pass by the school beacons. Although the median speed saw a significant reduction of 22% when the beacons were on, the speed of the 85th percentile was only reduced by 13%, implying that vehicles that are already above the speed limit are more likely to speed even when the school beacons are on.
School beacon and radar driver feedback sign in Sandy Springs, GA used to test whether the school beacons and sign slow the vehicles down as expected
Rear facing radar to measure the speed of the vehicles AFTER they have passed the “slow down” sign
