A method and apparatus for communicating estimated vehicular speed and length using data obtained from a single wire-loop. The detector card connected to a single wire-loop produces a first bivalent output based on the actual measurement of a vehicle at the wire-loop sensor and synthesizes a second bivalent output to mimic the output of a two wire-loop speed trap. By simulating a second bivalent output at the detector card level, a conventional field controller is capable of estimating the vehicular speed from a single wire-loop sensor.