| 摘要 |
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. The passageway may be formed with an oval or elliptical cross-section such that the minimum diameter of the cross-section extends in a vertical direction to enhance closure of the passageway to interrupt the radiation beam when the treadle is compressed. Opposite end portions of the treadle and the attached photocells are disposed in junction boxes embedded in the roadway, preferably, adjacent the traveled portions thereof. In the alternative, the emitter and collector may be of the single unit type which is disposed in one end of the treadle while a reflector is disposed at the other end.
|
