Speed at fixed sites is determined by using one of two technologies, below is a description of each:
AutoPatrol technology (radar):
Based on similar technology to air traffic control radar, this system provides true speed safety by tracking the distance, angle and speed of each vehicle. With the added benefit of vehicle tracking–up to 32 at a time, multiple concurrent violations can be detected and captured. It is capable of monitoring up to 6 lanes of traffic and dual direction.
Piezo strip technology
Two piezo strips are used to time a vehicle's location at two specific fixed points. Based on the time it takes a vehicle to travel from point A to point B, a speed calculation is made. A loop is placed between the two piezos to verify activation by a vehicle (inductive loop detects the presence of metal) rather than another source.
- There are two piezo strips "cut" into the road at a fixed distance apart (approximately 10-15 ft)
- Timing is started when the vehicle strikes the first piezo sensor which is verified by the rise of the loop
- Timing stops when the same "axle" strikes the second piezo
- Each "axle" is counted and measured for speed until the fall of the loop which signifies the end of the vehicle
- Each independent speed measurement (all subsequent axles relative to the first) are compared to the first axle speed
- The detection is valid if all speeds are accurate within preset tolerance limits
Once the initial conditions have been met (steps 1 -3) the camera is activated, when all conditions have been met the system verification is completed and the detection packaging sequence commences firing the cameras based on the vehicle's speed.