Journal of Engineering and Architecture

A Proposal for Managing Glare’s Effect on Tunnels: Abdoun Tunnel Case
Ayat Alkhreasat, Nessma Al-Hammadi, Farah Aboudi, Dr. Rezq Shaaban

Abstract
This paper describes a new method to address glaring effects that drivers face when entering or leaving road tunnels due to the huge difference between luminance inside and outside the tunnels, in particular during sunny days. The outside luminance of the direct sun is more than 200 Klux with more than 10000 Lux as the indirect luminance of the sky, while the luminance inside tunnels is less than 20 Lux at 50m from the entrances of the tunnel. This huge difference causes disability glare for a few seconds and could cause major accidents at the entrances of the tunnels. In many recorded cases in Amman City, artificial lighting in tunnels isn’t sufficiently maintained, and many lighting units are off or covered with dust. This research measures luminance inside Abdoun Tunnel in Amman City and proposes reflecting devices to light the entrances of the tunnel and allow a sufficient distance for the drivers to adapt with the less illuminated areas. The measured luminance in front of the tunnels varied between (10,000 to 40,000) Lux during March, which represents the average lighting of the year. On the other hand, luminance inside the tunnels after 50 m is less than 20 Lux. If the permitted speed inside the tunnels is 50 km/hours, then the timing required to reach this point is less than 6 seconds. Therefore, the eyes need to adapt with that difference within this time. A 1:20 scale model was constructed to simulate Abdoun Tunnel, and luminance is measured using 12 cell daylight factor meters inside the tunnel, 50m outside the entrance to 40m deep where the lighting is uniform. Sky and ceiling louvers were used to reduce external lighting 30m prior to the entrance, and special reflecting devices were used in the ceiling above the entrance of the tunnel, these devices are called the Anidolic system, which is used as shading device and to reflect daylight to the ceiling of the tunnel and increase the lighting level in the tunnel for a long distance; up to 100 m. Both arrangements decreased lighting level outside the tunnel from (65500 - 23150) Lux during December, and increased lighting levels luminance from (95 – 285) Lux at a distance of 40 m from the tunnel entrance, serving long distance inside the tunnel.

Full Text: PDF     DOI: 10.15640/jea.v7n2a9