Abstract: An apparatus designed to monitor traffic on a section of road of given length L for modifying the operation of a traffic light at an intersection approached by that road comprises speed-sensing circuits at opposite ends of the surveyed road section, the entrance-side circuit also emitting pulse trains reflecting the lengths Li of passing vehicles. A calculator determines from the measured entrance and exit speeds a mean overall speed VM which is inversely proportional to the mean transit time L/VM and enables the computation of an occupancy density DE(t)=.SIGMA.Li/L from which in turn an encumbrance P(t)=DE(t)/VM is derived. The traffic light can be controlled directly by a signal which is proportional to this encumbrance P(t), or which represents a related function F(t). An additional modification of the operating cycle of such traffic light can be brought about by a signal indicating the approach of a vehicle of unusual length on the surveyed road section.

Abstract: An automatic system for guiding moving objects is described which cooperates with passive responders situated on or along the road on which the system operates. The part of the system which is located aboard a vehicle comprises one or two optical transmitter/receiver units. The transmitter, comprising an emitter diode or two such diodes energized either continuously or alternately, emits a light signal in the form of a beam of radiation of limited dimensions covering a certain number of responders, which reflect a fraction of the light reaching them. The received signals make it possible to form an electrical signal whose amplitude and sign are a function of the position of the transmitter along an axis transverse to a longitudinal reference axis. This system is applicable to the automatic guidance of moving objects such as road vehicles along routes marked by responders.