Abstract: The present invention relates to a method and apparatus for measuring roughness along a surface (II) of a road or an airport runway in the driving direction. A long bar (I) has a number of ultrasound transducers (1-17) directed down toward the surface (II) of the road. The bar (I) is located e.g. in a carriage trailing behind a vehicle, at a suitable distance (for instance 20 cm) above the road surface (II). During motion, ultrasound pulses are simultaneously emitted form all transducers (1-17) for a subsequent recording of echoes from the road surface (II) with the same transducer, in order to obtain a recording of the distance between the bar and the road surface for each particular transducer. The measurement is repeated when the bar (I) has moved a distance equal to an integral multiple of the distance between two neighboring transducers, in such a manner that a number of the previously measured spots are measured once more, i.e. an overlap technique is used.