VISIBILITY STUDY FOR LONG VEHICULAR TUNNELS

A review is made of tunnel illumination design guides in which it is shown that great variations exist in the suggested luminance for the threshold zone. Major causes of these variations in visibility requirements at the tunnel entrance are the ambient luminance of the area, the orientation and geometrics of the structure, the alignment of approaches, materials used for pavement and portal facing, traffic speed, volume, relative location in the road system (rural, urban, flat or mountainous terrain), and the desired level of service. Following a discussion of these factors, attention is turned to tunnel interior illumination. Charts are presented which show the luminance requirements that should produce a smooth transition from the threshold to the transition zone, and finally to the interior of the tunnel. Close luminaire spacing, inter-reflection, and light overlap enable such luminous intensities to be produced, thereby giving this smooth transition. It is stressed that the curves shown are not recipes for tunnel lighting, but should be treated as examples of the "visibility study method." It does appear, however, that as a general guide the upper limit of the maintained liminance of 350 cd/sq m and the lower limit of 150 cd/sq m may be used at tunnel entrances.

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  • Supplemental Notes:
    • Presented at the Annual IES Conference, July 14-18, 1974, New Orleans, La.
  • Corporate Authors:

    Illuminating Engineering Society

    120 Wall Street, 17th Floor
    New York, NY  United States  10005-4001
  • Authors:
    • KETVIRTIS, A
  • Publication Date: 1975-1

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Filing Info

  • Accession Number: 00081229
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Mar 6 1975 12:00AM