Method for detecting and documenting traffic violations at a traffic light
A method for detecting and documenting red-light violations and/or speeding violations in which a radar beam is directed across all lanes of a roadway of interest and in which the speed and the position of a vehicle which passes through the radar beam are determined from the radar signals so as to be able to predict the probability of a red-light violation from the speed and the determined distance of the measured vehicle from a stop line and to trigger the recording of images of the violating vehicle at predetermined distances from the stop line.
1. A method for detecting and documenting traffic violations at a traffic control light in which passage of vehicles through a predetermined observation area is determined by deriving distances for respective points of impingement of radar signals that are reflected by said vehicles and by determining whether said distances, and thus said points of impingement, are located within a distance range defined by said observation area, the position of which relative to a transmitting and receiving site of said radar beam is known, comprising:
directing said radar beam at least at one lane of a roadway, wherein a radar lobe formed by said radar beam forms said observation area, which, in the direction of travel of said vehicles, is located at least partially before a stop line;
determining the relative position of said stop line marked on lanes of said roadway relative to said transmitting and receiving site of said radar beam;
deriving the relative position of a point of impingement on one of said vehicles located within said observation area relative to said transmitting and receiving site of said radar beam from radar signals reflected from said one of said vehicles;
determining the perpendicular distance to a stop line from the known relative position of said stop line and the position of a point of impingement on said one of said vehicles and is linked with said point of impingement;
deriving the speed of said one of said vehicles from said radar signals and linked with the points of impingement; and
determining the time point at which the vehicle crosses said stop line based on said derived speed and the distance of the point of impingement of said one of said vehicles from said stop line and if said time point is outside the green-light phase of said traffic control light associated with said stop line, initiating the creation of an image of said vehicle.
2. The method of claim 1 , wherein, based on the relative position of the points of impingement, a lane of said roadway is determined and the associated speed of said vehicle is compared with a cut-off speed specified for the respective lane, and wherein the creation of an image of said vehicle is initiated if said speed of said vehicle is higher than said cut-off speed.
3. The method as in claim 2 , wherein determining the time point at which at least one image is initiated is based on said derived speed and a known distance from an image point.
4. The method as in claim 3 , wherein the distance to a stop line equals the distance to an image point of initiating the creation of said image.
5. The method as in claim 3 , wherein the distance to a stop line is greater than the distance to said image point.
6. The method as in claim 1 , wherein said radar beam is directed at an acute mounting angle and horizontally with respect to the direction of travel across said lanes of said roadway, and the radar lobe is such that the distances that can be derived from reflected radar signals of a vehicle that moves within a lane can be unequivocally linked with only one lane and the positions of the points of impingement are defined by way of the distances derived from said radar signals.
7. The method as in claim 6 , wherein said observation area is determined by the side lane boundaries and the marginal rays of said radar lobe.
8. The method as in claim 1 , wherein said radar beam is directed at said lanes of said roadway at an acute angle and inclined perpendicular to the roadway surface, and said radar lobe is sufficiently wide so that said radar beam impinging on the roadway surface forms a beam spot which extends across all lanes, and the positions of the points of impingement are defined by way of the distances derived from the radar signals and angles relative to the axis of a radar antenna of the radar device that receives the radar beam.
9. The method as in claim 7 , wherein said observation area is determined by the beam spot.
10. The method as in claim 1 , wherein said radar beam is directed at an acute mounting angle and horizontally with respect to the direction of travel across said lanes of said roadway and the radar lobe is sufficiently wide so that the derived distances can be linked not only with a single lane, and the positions of the points of impingement are defined by way of the distances derived from the radar signals and angles relative to the axis of a radar antenna of the radar device which receives the radar beam.
11. The method as in claim 10 , wherein said observation area is determined by the marginal rays of said radar lobe and two imaginary lines of a predetermined distance which connect the marginal rays.
12. The method as in claim 11 , wherein said predetermined distances are spaced more than 10 m apart.
13. The method as in claim 1 , wherein said distance is determined by a pulse time measurement by means of a laser.
14. The method as in claim 1 , wherein speeding violations are detected during times in which the function of said traffic light is turned off.