Road Surface Photometric Characterisation and Its Impact on Energy Savings

How road surfaces reflect light in space is a physical characteristic that plays a key role in the design of road lighting installations: by European Standards the average luminance is the target quantity to assure the required safety conditions of the motorized road traffic. Lighting systems are designed (luminous flux installed per kilometre) to comply with the above requirement, starting from reference values of road surfaces reflection published in an old scientific document. These data are obsolete and not representative of current road surfaces, but they are still used to design current LED lighting systems. European Community funded a SURFACE project to provide to EU standard organization new traceable reference data, representative of current road surfaces used in EU. The paper presents the data collections and the impact on road lighting of using available old reference data versus SURFACE collected data of current road surfaces. Results highlight advantages in using bright pavements as well the need for introducing systems for flux control in road lighting installation to compensate for the discrepancies between current reference data and actual road surface data.