US Patent 11021159 Road surface condition detection

A system includes a computer comprising a processor and a memory. The memory stores instructions such that the processor is programmed to determine, based on vehicle lidar sensor data, a reflectivity of an area of a road surface, and to determine whether the area is wet based on the determined reflectivity of the area, a dry-condition reflectivity threshold for the area, and an angle of viewing the area from the lidar sensor.