That approach is beginning to bear fruit. However, another cost-effective approach is to reduce the problems with the large base of installed inductive loop sensors. The first step to solve the problems with IL sensors is to analyze how the sensor works. The inductive loop sensor is a relatively simple sensor. When a vehicle reaches the loop, the metal of the vehicle disturbs the magnetic field over the loop, which causes a change in the loop s inductance.
Inductance is an electrical property that is proportional to the magnetic field.
This is how the loop sensor detects a vehicle. The current passing through the loop generates an electromagnetic field. When a vehicle passes through the field, it acts as a conductor, changing the inductance of the loop. The sensor detects this change and notifies the traffic-signal controller of its finding. There are a wide variety of possible causes for IL failure such as damage to insulation during shipment but the two most common reasons for failure are poor pavements and poor installation techniques.