Abstract: An apparatus for measuring the evenness of a substructure, e.g. a road surface, is fitted to a vehicle. The free ends of a number of pivotable measuring arms, uniformly spaced side by side over the entire vehicle width, engage the substructure resiliently during measurement. Each measuring arm is pivotably mounted in a measuring housing which has a plate spring coacting with each arm. On pivotation of the arm relative to said housing, as a result of unevenness in the substructure, the plate spring executes a corresponding deflection, sensed by strain gauges attached to said spring and giving output signals, proportional to the deflection, to an electronic unit wherein the signals are converted to output data representing the surface evenness of the substructure.