How Traffic Lights Detect Your Car

How Traffic Lights Detect Your Car The lines sawn into the pavement at a stoplight are basically an electromagnet listening for metal. When your car sits over them it lowers the loop's inductance and the circuit's frequency jumps, which is how the controller knows you're waiting. It's also why a motorcycle sometimes can't get the light to change. This is the physics hiding in the asphalt, right down to the equation. Sources (linked so you can check the work): U.S. FHWA: Traffic Detector Handbook, 3rd edition (FHWA-HRT-06-108) https://www.fhwa.dot.gov/publications... Jalopnik: the 20-plus US states with dead red laws, letting a motorcycle legally proceed through a red light a loop is too insensitive to detect https://www.jalopnik.com/1926245/us-s... NEMA TS 2 detector standards (excerpted by FHWA): inductive-loop detector specifications https://www.fhwa.dot.gov/publications... Every diagram and animation is built from scratch for this topic. No stock clips, no templates. Some background images are AI-generated (disclosed per YouTube policy). New explainer every week. Subscribe: @beneaththewires #engineering #traffic #howitworks #physics