These guidelines and recommendations provide the best practices for radar speed sign installation to assure successful, accurate and effective traffic calming.
- Do not install a solar powered radar speed sign under a tree. Summer leaves on the tree could impact solar recharging. Make sure the solar panel is installed facing as close to South as possible.
- Do not install the radar speed sign within 100 feet of a curve. A radar speed signal cannot ‘curve’ with the road, and will not display speeds with enough time for drivers to see the alert and adjust their speed.
- The radar speed sign should be installed no more than 5 feet from the road curb. At more than 6 feet from the road, the sign will take the eyes of the driver an unsafe distance from the roadway, and result in displayed speeds that are LOWER than the actual speed.
- The sign direction should be perpendicular to the road with the radar pointing directly at the curb, not at the center of the road for maximum vehicle detection. Signs rotated toward the center of the road will not perform as well.
The radar speed sign should be installed 7-10 feet off the ground. Do not install the radar speed sign lower than 4 feet off the ground. Doing so will result in much of the radar speed signal being absorbed by the road, reducing your detection range.
Prior to radar sign installation look for any obstructions (telephone poles, large tree limbs, other signage, etc.) that might interfere with proper operation of the sign.
Installing the sign on the same side of the street as parallel parking of vehicles could affect the radar performance of the radar speed sign. The radars speed sign should be installed high enough off the ground to detect oncoming traffic over the parked vehicles.
If the radar speed sign is installed more than 12 feet above the roadway the sign should not be tilted more than 3°- 4° downward to detect vehicles. Doing so will result in a greatly reduced length of time vehicles will be detected, and will display speeds that are LOWER than actual speed. (the cosign effect).