Skip to main content

Solid-State Roadway Lighting Design Guide: Volume 1: Guidance (2020) / Chapter Skim
Currently Skimming:

Glossary
Pages 61-66

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.


From page 61...
... average maintained illuminance.  The average level of horizontal illuminance on the roadway pavement when the output of the lamp and luminaire is diminished by the maintenance factors; expressed in average footcandles (lux) for the pavement area.
Read the entire page →
From page 62...
... equipment factor.  A factor used in calculations of illuminance or luminance to compensate for light losses resulting from normal production tolerances of commercially available luminaires as compared with laboratory photometric test models. fixture. See luminaire.
Read the entire page →
From page 63...
... factor.  The multiplier to be used in illumination calculations to relate the initial rated output of light sources to the anticipated minimum rated output based on the relamping program to be used. (See the discussion of light loss factor in Chapter 10)
Read the entire page →
From page 64...
... mean lamp lumens.  Mean lumen output of a lamp; it is calculated by determining the area beneath the lumen maintenance characteristic curve of that source over a given period of time and dividing that area by the time period in hours. mercury lamp.  An electric discharge lamp in which the major portion of the radiation is produced by the excitation of mercury atoms.
Read the entire page →
From page 65...
... It shows only the percentage of bare lamp lumens that fall on the horizontal surface and is plotted as a ratio of the width of the area to the mounting height of the luminaire. veiling luminance.  Luminance superimposed on the retinal image that reduces the image contrast.
Read the entire page →
From page 66...
... visual acuity.  A measure of the ability to distinguish fine details. Quantitatively, it is the reciprocal of the angular size (in minutes)
Read the entire page →

Key Terms

  • visual field
  • luminous intensity
  • light center
  • roadway lighting
  • reflecting light

  • photometric brightness
  • square meter
  • luminaire light
  • light distribution
  • average footcandles

  • average level
  • mounting height
  • discharge lamp
  • average luminance
  • surface emitting

  • horizontal illuminance
  • diffusing surface
  • lamp lumens
  • square foot
  • light source

  • uniform luminance
  • light loss
  • distributed flux
  • flux incident
  • uniformly distributed

  • visual performance
  • flux leaving
  • interchange lighting
  • street lighting
  • line plotted


    • This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
    More information on Chapter Skim is available.