a signal light including a housing is recessed into a traffic surface and projects minimally upwardly from the surface and wherein a light processing assembly is provided to receive light from a light source , intensify the light and direct the light toward a light outlet in a generally linear manner , the arrangement for processing light being mounted to the housing . for this purpose , the light source is designed in such a way that it sends an essentially linearly directed light beam onto the light processing assembly . the light is collected in the light processing assembly in such a way that , when it exits , it is still linearly extending in at least one direction but it has a higher intensity . for this purpose , the light processing assembly includes a cylindrical - convex lens entry surface and a cylindrical concave mirror surface for receiving and directing light .