The optical barrier is used in the motorway toll lanes to survey the vehicle cadence. These parameters are used to determine the tariff. It consists of two parts (transmitter and receiver ), positioned on the sides of a single lane. These parts generate and receive an infrared and orthogonal light in the direction of the vehicle. The SP15 model allows two additional features: the height detector at 2200 mm. and the detector of direction of the vehicles. The two elements consist of painted steel cabinets that include respectively transmitter and receiver units. The 2200 mm. height detector is on the same axes of the barrier; the detector of direction is positioned at 700 mm. height from ground at 200 mm. far from the axe of the barrier. This device is exempt from manual regulations 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. The two additional sensors for 2200 mm. eight and direction are made with the same infrared technology controlled by the same cpu of the main functioning.