We propose a radio–optical method for monitoring the state of the road surface. In the optical part, the road surface condition is determined by the depolarization degree of radiation reflected from the road surface. The linearly polarized radiation is directed to the road surface. The paper presents some results of model tests on asphalt covered with snow, ice, and snow–water mixture. The radiowave part of the setup makes it possible to detect the presence of ice under the snow layer.