Saf Health Work.  2017 Jun;8(2):151-155. 10.1016/

Safety Evaluation of the Lighting at the Entrance of a Very Long Road Tunnel: A Case Study in Ilam

  • 1Department of Occupational Health, School of Public Health, Ilam University of Medical Sciences, Ilam, Iran.
  • 2Occupational Health Research Center, Qom University of Medical Sciences, Qom, Iran.
  • 3Department of Occupational Health, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
  • 4Faculty of Medicine, Khatam Al-Nabieen University, Kabul, Afghanistan.
  • 5Occupational Health Research Center, Iran University of Medical Sciences, Tehran, Iran.


At the entrance of a tunnel, reflection of sunlight from the surrounding environment and a lack of adequate lighting usually cause some vision problems. The purpose
of this study was to perform a safety evaluation of lighting on a very long road in Ilam, Iran.
The average luminance was measured using a luminance meter (model S3; Hagner, Solna, Sweden). A camera (model 108, 35-mm single-lens reflex; Yashica, Nagano, Japan) was used to take photographs of the safe stopping distance from the tunnel entrance. Equivalent luminance was determined according to the Holliday polar diagram.
Considering the average luminance at the tunnel entrance (116.7 cd/m²) and using Adrian's equation, the safe level of lighting at the entrance of the tunnel was determined to be 0.7.
A comparison between the results of the safe levels of lighting at the entrance of the tunnel and the De Boer scale showed that the phenomenon of black holes is created at the tunnel entrance. This may lead to a misadaptation of the drivers’ eyes to the change in luminance level at the entrance of the tunnel, thereby increasing the risk of road accidents in this zone.


Keywords; black hole; De Boer scale; safe level of lighting; tunnel lighting
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