A METHOD FOR ILLUMINATING A TUNNEL OF A HIGHWAY

摘要

A method for illuminating a spot inside a tunnel of a highway by the use of a solar ray collecting device which is to be used to focus a solar ray and guide it into an optical conductor. The solar ray transmitted through the optical conductor would illuminate an entrance portion of the tunnel and a light-emitting portion of the optical conductor would disperse so as to gradually weaken the illumination inside the tunnel in accordance with an increase of distance between the entrance portion and a spot to be illuminated in an inner space of said tunnel.