Equivalent exciting force of a large truck running on an asphalt road was calculated from the ground vibration records by employing the 3-dimentional hybrid model combining the thin layer and the finite element methods. The equivalent exciting force was compared with the dynamic inertia force of the truck's body. The analysis results showed that the ground vibration amplitude was not significantly affected by velocity of the running track, indicating that it is appropriate to assume a fixed exciting point for simulating ground vibrations. Furthermore, effect of coupling of 3(xyz)-components...