Method and apparatus for measuring axle load of a running vehicle

Axle load meters are arranged in an axle load measuring area of a road. Instantaneous axle load values W1, W2, . . ., Wn are sampled from outputs of the axle load meters at time points t1, t2, . . ., tn as measured from a time point when the running vehicle enters the axle load measuring area. Pairs of instantaneous axle load values (W1, W1+Tk), (W2, W2+Tk), . . ., (Wi, Wi+Tk) at time points (t1, t1+k), (t2, t2+k), . . ., (ti, ti+k) each having a fixed time interval Tk (k=1 to j) are determined based on the measured instantaneous axle load values W1, W2, . . ., Wn, and average values W1Tk, W2Tk, . . ., WiTk of the respective pairs are calculated, to thereby produce average value groups for the respective fixed time intervals T1, T2, . . ., Tj. An average value group having a minimum variation is selected from the average value groups, and an average of the selected average value group is employed as the axle load of the running vehicle.