Abstract: A pneumatic road tube, a pressure responsive transducer, and an electronic circuit provide a vehicle sensor mechanism for use in a traffic data accumulating system. A complex air wave is produced within the tube each time a vehicle axle runs over the tube, these waves are sensed by the transducer which responds by producing an electric output signal indicative thereof. The transducer output signals are coupled to the electronic circuit which amplifies weak signals and blanks out unwanted portions thereof to produce signals suitable for application to the data accumulating device. The electronic circuit may be present by an operator to accurately respond to the various types of transducer output signals produced by slow, medium, or high speed traffic.