System for optically detecting vehicles traveling along the lanes of a road

A system for optically detecting vehicles traveling a road having a plurality lanes, said system comprising:

• a gantry provide at the road so as to straddle the plurality lanes;
• a plurality of optical line sensors provided on said gantry, for getting linear images of a surface of the road, said optical line sensors arranged in two rows and in a staggered pattern such that each has a view field overlapping the view field of either adjacent optical line sensor by the sum of half the view field and a width of a motor cycle the optical line sensors having an optical axis;
• photoelectric sensor apparatus consisting of photo-projector elements and photo-detector elements, and having optical axes which are parallel to each other and are substantially located in the position of the view fields of said optical line sensors;
• and
• a signal-processing section for detecting a vehicle traveling under said gantry in accordance with output signals of said optical line sensors and output signals of said photoelectric sensor apparatus, by using reference signals which said optical line sensors generate when no vehicles travel under them;
• wherein the optical axis of the optical line sensors and the optical axes of the photoelectric sensor apparatus intersects with each other.