Abstract: Vehicle longitudinal-vibration road spectrum and itsapplication in a road-vehicle system are discussed. The vehicle longitudinalshearing force and the stress intensity factor of the pavement under the forceare computed. Compared with the vertical road spectrum, the roadlevel of the longitudinal road spectrum is better. The vehiclelongitudinal shearing force is represented bya steady stochastic process whose mean value is zero. The pavement crackgrowth speed from upper to lower is evidently faster than fromlower to upper. The speed is proportional to the fourth power of the vehiclelongitudinal shearing force, by which, the pavement damage is by fargreater than the vertical tyre force.