Pavement cross-slope is measured at highway speeds by mounting a ring-laser gyroscope on a vehicle and measuring deviation of the transverse slope of the vehicle. Precise laser distance measuring devices are mounted transversely with respect to the vehicle at significantly distant points to measure vehicle roll by measuring displacement of the laser distance measuring units from the pavement. The difference between at rest measurements of the laser distance measuring devices, the dynamic measurements produced by those devices and the relation of the dynamic measurement to the distance between the measurements provides the exact value of vehicle roll with respect to the pavement. That exact value of vehicle roll is compared with the ring gyro angular measurement to produce a precise measurement of pavement slope. A positional device is mounted on the vehicle for determining the position of the vehicle on the roadway. A computer is mounted on the vehicle and a recording device is mounted on the vehicle to record the precise slope of the roadway at the precise position on the pavement being measured.