Abstract: An optical treadle of extended longevity is disclosed. The treadle is of unitary construction with an improved cross-sectional passageway shape that more effectively interrupts light when a vehicle tire passes thereover. A treadle assembly with permanently affixed light transmitting and light receiving means is also provided such that a failed assembly can be quickly replaced as a unit. Further, a roadway treadle assembly comprising a frame for installation in a roadway and an adapter plate for adapting a preexisting treadle frame are provided for mounting the treadle assembly across a surface portion of a roadway.

Abstract: A treadle switch assembly for installation in a roadway bed for use in sensing vehicular traffic flow thereover is disclosed. The assembly includes at least one elongated treadle constructed of a compressible, resilient material which contains a hollow passageway throughout its length. Also included is a photocell emitter and a photocell collector, which elements are connected to opposite ends of the treadle and inserted into opposite ends of the passageway. When the treadle is compressed by a vehicle tire, the passageway is mashed closed to interrupt the radiation beam from the emitter to the collector, whereby the collector generates a signal indicative of the passage of the vehicle tire thereover, which signal may be used to operate a suitable counter or signal device as desired.