Each axle weight of in-motion vehicles is measured with an axle weighing system, by processing the output signal from the load sensor. Since the output is contaminated with the noise due to the vibration of the vehicle and the data length is extremely short, the signal processing technique is the key to achieve an accurate measurement. In this paper, an equation for estimating axle weights is derived from a normal equation on the assumptions: 1) The output is stationary process described by a

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... nstant and the superposition of sin-functions when the vehicle tires are completely on the weighbridge. 2) The solution of a difference equation concerning the output corresponds to the constant and superposition mentioned above. The feasibility test results of the method using a cabover-engine dump truck under different experimental conditions are also described.