In night-time driving, road lighting is important to road safety. Consequently, it is important that the performance of the lighting is satisfactory, not only immediately after installation, but also over time. Therefore, the performance, which in most cases is described by the road surface luminance, should be checked regularly, using condition assessment. Condition assessment of road lighting is preferably carried out using mobile measurement equipment. However, luminance is difficult, or even impossible, to measure at speed. The luminance of a road surface is partly dependent on the illuminance and partly on the reflection properties of the surface. The first parameter should be possible to measure at speed, while the latter might be characterized by the daylight luminance coefficient, which can be measured using a hand-held instrument. This report describes an attempt to predict the luminance of a road surface in road lighting from mobile measurement of illuminance and hand-held measurement of the luminance coefficient in few measurement points on the surface. The luminance can then be estimated as the product of these two parameters.