The reflection characteristics of the road surfaces play a key role in the design of road lighting installations, when the average luminance is the target quantity standards specify to assure the required safety conditions of the road traffic. The measurement of the reflection characteristics of the road surface can be done in laboratory, using road samples, or on-site using peculiar instruments. This paper describes a simple technique for on-site characterization of a road surface. In its simplest formulation this technique requires only a matrix luminance meter, i.e. an imaging luminance measuring device (ILMD) and a calibrated white or grey reference flat surface. In this case the SI calibration of the luminance meter is not required.