induction loops as so called "old fashioned sensor":)

this is an example of magnetic fields of a plane.


you know in germany at many intersecions there are those induction loops on the street.
they control the traffic lights at night mainly.
- they work with electricity and react to the metal in cars that change the voltage.
- they register cars and change the traffic lights.
- if u put such an induction loop behind the stop line at an intersection you can register and
track knowing violation against red lights.
- if u put two of those at one certain place u can recognize the type of a car and its speed!!
- they work under every condition


i think its so simple but effective. i like.
they are trying to install those sensors on the frankfurter airport.