Controversial results from different studies of the luminance required in the entrance zone of vehicular tunnels lead to the development of the method described to obtain the actual adaptation luminance of the observer in approaching the tunnel. The equivalent veiling luminance following from the luminances occurring in the visual field can be computed for different fixation points and distances to the tunnel. LS(eq) superimposes on the luminance of the area around the fixation point and has the effect of decreasing the contrast of a small target to be perceived in its centre. Since its contrast reduced in such a way has always to be 0.2 to ensure visibility under practical conditions the required entrance luminances for different LS(eq) levels and target contrasts can be derived by calculation. /Author/TRRL/

  • Availability:
  • Corporate Authors:

    Illuminating Engineering Society

    York House, 199 Westminster Bridge Road
    London SE1 7UN,   England 
  • Authors:
    • ADRIAN, W
  • Publication Date: 1976

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00147637
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Analytic
  • Files: ITRD, TRIS
  • Created Date: Jun 22 1977 12:00AM