System and method for detecting the circulation condition in a vehicle

The system has a headlight (10) provided with a light source (15) emitting visible light beam, and a laser diode (11) emitting an infrared light beam in direction of road scene. A camera (32) captures images of the road scene. A photodetector (36) receives infrared light beam reflected by the scene. A semi-transparent plate (38) directs a part of the beam reflected towards the photodetector. Independent claims are also included for the following: (A) a method of detecting traffic conditions (B) a motor vehicle including a traffic conditions detecting system.