The purpose of the paper is to present some simple but effective techniques for detecting vehicles in motion based on the energy radiated from the axles. These techniques can be applied to the implementation of vehicle counters and detectors for traffic management control. In general, the proposed techniques work well with acoustic signals acquired by regular recording devices. Thus, they offer a significant advantage as their implementation can be done inexpensively. The paper discusses an interesting observation that the radiated energy from axles possesses certain unique acoustic characteristics. The fundamental approach takes advantage of various signal modeling techniques in the development of a signal model that captures the unique characteristics of the axles acoustically. This requires the use of correlation methods as well as Fourier techniques. In addition, the paper addresses certain issues pertaining to the real time implementation of these techniques.