1. A system determining sheeting type of a reflective sheeting material covering a road sign comprising: at least one light source mounted on a vehicle capable of traversing a roadway and suitable for illuminating at least a portion of the road sign; at least one light intensity sensor for receiving light reflected from the road sign and computing the intensity of the received light; a positioning system for determining a location of the vehicle from a stationary frame of reference; a ranging system for determining a distance of the road sign from the light source and an inclination of a surface of the road sign relative to the light source; a control system operably connected to the light source, intensity sensor, positioning system and ranging system such that the intensity sensor, ranging system and positioning system record information associated with an area that includes at least one road sign as the vehicle traverses along the roadway in response to repeated illumination of the area by the light source; and a computer processing system that utilizes the recorded information to determine an as-measured retroreflectivity profile having an as-measured shape and comprising the plurality of as-measured retroreflectivity values for the sheeting type of the road sign and comparing the as-measured shape with a characteristic shape of at least one known retroreflectivity profile in a database of known retroreflectivity profiles for each of a plurality of different sheeting types to classify a sheeting material of the road sign as one of the plurality of different sheeting types.