In this work, effects of the structural measures during the construction phase on the tunnel lighting have been studied. The luminance of the access and threshold zones of the tunnel are obtained from the photos taken from the entrances of Gultepp and Diliskelesi Tunnels located on the Istanbul-Ankara TEM motorway in Turkey according to the CIE Publication No. 88. Then the effects of the tunnel surroundings, direction, traffic speed, road pavement and portal design on the tunnel-lighting design-criteria have been investigated by using real tunnel entrance photos taken from certain distances and/or computer generated images. Consequently, it has been explained that significant decreases in the tunnel illumination levels can be achieved by taking the structural measures in tunnels. (C) 2003 Elsevier Science Ltd. All rights reserved.