SECO-LARM U.S.A., Inc.'s Enforcer (LD-1123-PAQ) Loop Detector is an inductive-loop traffic detector designed to be used with gates or other vehicle detection systems. The Loop Detector senses when ...

As you may have guessed, this kind of detector works by detecting an inductance change in a wire loop (aka coil) buried in the road.

For anyone unfamiliar with the original project, the circuit detected a vehicle via an inductive loop and was able to perform a task like opening a gate.

Vehicle detection loops can be installed discreetly under the tarmac allowing the presence of vehicles to exit the gates and prevent closing whilst obstructed. Sliding gates versus swinging gates ...

The Automated Vehicle Occupancy Detection systems uses two video cameras and some analytics algorithms to surveil cars in carpool lanes and ticket them if they don’t have enough passengers.