ILLUMINATION DESIGN FOR VEHICULAR TUNNELS

ILLUMINATION DESIGN FOR TUNNELS MUST CONSIDER FOUR FUNCTIONAL ELEMENTS OF THE TUNNEL: THE APPROACH, THE ENTRY PORTAL, THE TRAVERSE, AND THE REENTRY INTO THE OPEN. IN ADDITION, THE GEOMETRIC AND TRAFFIC CHARACTERISTICS OF TUNNELS VARY WIDELY AND REQUIRE DIFFERENT LIGHTING PRACTICES. FOR EXAMPLE, A TUNNEL UNDER A RIVER WILL BE CONCAVE WITH RESPECT TO THE SURFACE, WHILE ONE ACROSS THE HUMP OF A MOUNTAIN MAY BE CONVEX, WITH DIFFERING EFFECTS ON LINE OF SIGHT AND VISUAL ADAPTATION. A RURAL TUNNEL SERVING PRIMARILY LOCAL TRAFFIC WILL HAVE DIFFERENT LIGHTING REQUIREMENTS FROM ONE THAT SERVES AS PART OF AN URBAN EXPRESSWAY. THAT THERE IS CONSIDERABLE DIVERSITY IN THE HANDLING OF THESE PROBLEMS CAN BE SEEN FROM THE EUROPEAN AND JAPANESE STANDARDS FOR THE RATIO OF APPROACH LUMINANCE TO THAT OF THE TUNNEL THRESHOLD ZONE; THE JAPANESE STANDARD OF 40:1 SEEMS MORE REALISTIC THAN THE 10:1 REQUIRED IN EUROPE. THE EUROPEANS ALSO MAKE USE OF SUN SCREENS TO PROVIDE A MORE GRADUAL TRANSITION FOR THE EYE; HOWEVER, THESE ARE VERY EXPENSIVE, ARE AFFECTED BY WEATHER CONDITIONS, NECESSITATE SOME KIND OF MAINTENANCE TO PREVENT PAVEMENT ICE AND SNOW ACCUMULATIONS, AND MUST BE LIGHTED AT NIGHT. OTHER FORMS OF SUPPLEMENTARY LIGHTING ARE HIGH-INTENSITY LIGHTING AND THE "LUMINOUS GALLERY," WHICH HAS BEEN SUCCESSFULLY EMPLOYED IN CANADA. VISIBILITY WITHIN THE TUNNEL PROPER IS A FUNCTION NOT ONLY OF LIGHTING BUT ALSO OF COLOR, COLOR CONTRASTS, MATERIALS, AND GEOMETRY. THE TUNNEL EXIT IS MUCH LESS A PROBLEM THAN THE ENTRANCE BECAUSE UPWARD ADJUSTMENT OF THE VISUAL SYSTEM IS FASTER THAN DOWNWARD AND BECAUSE ADJUSTMENT BEGINS AS SOON AS THE EXIT PORTAL COMES INTO VIEW. FOR THIS REASON SUPPLEMENTARY ILLUMINATION AT THE EXIT IS NOT EFFECTIVE. AT NIGHT, HOWEVER, IT WOULD BE ADVISABLE TO INCREASE ROAD ILLUMINATION BEYOUND THE EXIT PORTAL TO 3 FOOT-CANDLES INSTEAD OF THE 1 FC CURRENTLY IN USE, TAPERING THIS LUMINANCE DOWN TO NORMAL LIGHTING OVER A DISTANCE OF ABOUT 1500 FEET.

  • Authors:
    • KETVIRTIS, A
  • Publication Date: 1972-8

Media Info

  • Features: Figures; Photos;
  • Pagination: p. 33-43
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00221789
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Feb 3 1973 12:00AM