Study of light-pipes for the use of sunlight in road tunnels: From a scale model to real tunnels

Abstract The necessity of saving energy from the electrical lighting in road tunnels demands alternative solutions, especially concerning the use of the cheapest and most ecological light source: the sun. In this work, the principles of sunlight distribution inside the tunnels themselves by means of light-pipes are developed and considered. The study is based on a scale model in which exhaustive calibration and adaptation to the situation in real tunnels is presented and discussed. Finally, the advantages of the philosophy of light distribution versus other means of using sunlight in road tunnels are analyzed and highlighted.