The double Optical barrier is used in the motorway toll lanes to survey the vehicle cadence, to determine the ride direction and to detect the vehicle height above the first axle. These parameters are used to determine the tariff. It consists of two columns positioned on the sides of a single lane. These columns generate and receive an infrared and orthogonal light in the vehicle direction. Two parallel and synchronous scanning are able to determine the vehicle presence, the overcoming or not of a specific height in correspondence of the first axle, the trailer presence to the tractor and to determine the ride direction. The two elements are equal and consist of Fiberglas cabinets that include two chassis transmitter and receiver cards and the adjustable height detector. This device is exempt from manual regulations during the functioning and provides a self-diagnostic software that, in case of failure or dirt, allows its operation in a degraded way with a special external signal.