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PHYSIOLOGICAL ASPECTS OF THE LIGHTING OF TUNNEL ENTRANCES

A DRIVER APPROACHING AN INADEQUATELY LIT TUNNEL ENTRANCE IS AT FIRST INCONVENIENCED SOLELY BY INDUCTION EFFECTS /HE SEES THE ENTRANCE AS A BLACK HOLE/. AFTER HE HAS PASSED THE POINT WHERE VISUAL ADAPTATION BEGINS /THE ADAPTATION POINT/ HIS VISION IS IMPAIRED PURELY BY ADAPTATION EFFECTS, IN PARTICULAR BY AFTER-IMAGES. INDUCTION EXPERIMENTS IN THE LABORATORY SHOW THAT THE BLACK-HOLE EFFECT IS AVOIDED WHEN THE LUMINANCE AT THE TUNNEL ENTRANCE IS GREATER THAN 10 PERCENT OF THE OUTSIDE LUMINANCE. THIS PROPORTIONALITY ALLOWS THE USE OF OVERHEAD GRIDS FOR LIGHTING THE TUNNEL ENTRANCE BY SUBDUED DAYLIGHT. THE INCONVENIENCE CAUSED BY AFTER-IMAGES WAS INVESTIGATED BY ABRUPTLY DECREASING THE LUMINANCE OF A LARGE SCREEN AND STUDYING THE TIME TAKEN FOR THE EFFECT OF THE AFTER-IMAGES TO DECREASE TO AN ACCEPTABLE LEVEL, AND ALSO BY ALLOWING OBSERVERS TO VARY THE LUMINANCE THEMSELVES. THE OPTIMUM LUMINANCE CURVE WAS DERIVED FROM THESE EXPERIMENTS. THE TIME REQUIRED FOR ADAPTATION WITH AN INITIAL LUMINANCE LEVEL OF 8000 CD/METER SQUARED AND A FINAL LEVEL OF 13 CD/METER SQUARED PROVES TO BE ROUGHLY 15 SEC /CORRESPONDING TO 300 M AT A DRIVING SPEED OF 72 KM/H, 45 MPH/. EXPERIMENTS WITH MODELS CONFIRMED THE RESULTS. THE LIGHTING REQUIREMENTS DETERMINED BY THESE EXPERIMENTS ARE MET BY THE LIGHTING PLANNED FOR THE COEN TUNNEL NOW BEING BUILT UNDER THE NORTH SEA CANAL TO THE WEST OF AMSTERDAM.

  • Supplemental Notes:
    • Vol 27, No 3/4, PP 76-86, 17 FIG, 15 REF
  • Corporate Authors:

    N/A

    ,   United States 
  • Authors:
    • SCHREUDER, D A
  • Publication Date: 1966

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  • Accession Number: 00219641
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Nov 10 2003 12:00AM