A magnetic sensor detects vehicles by measuring the change in the earth's magnetic field as the vehicles pass over the detector.
The sensor is either buried in the road, or enclosed in a box by the side of the road.
If vehicles are following each other very closely, the magnetic detector may have difficulty discriminating between them.
A more accurate and convenient solution is video vehicle counting and classification.
Retail Sensing have nearly 50 years experience in measurement and control. We have 15000 video counting systems installed in over 40 countries.