Why do we need Luminance Contrast

  • March 22, 2008
  • Bruce Bromley

What is Luminance contrast?
The amount of light reflected from one surface or component, compared to the amount of light reflected from the background or surrounding surfaces.

Why do we need it?
The majority of people who are blind or vision impaired have some vision. The provision of sufficient luminance-contrast in the design of signage and the choice of TGSIs will enhance access to information for people with vision impairment and for all pedestrians.

The use of luminance-contrasting strips on the nosing of stairs has been proven to improve safety for people who are vision impaired, as well as for all pedestrians.

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Installed December 2007, photo taken January 2008. Luminance contrast = 3%

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Photo taken January 2008. Luminance contrast = 8%

Examples of Good Contrast

Whilst the installation is not correct the following examples clearly show the effectiveness of luminance contrast.

My recommendation re colour selection is to NEVER use white TGSIs on any natural concrete surface. Even new TGSIs installed on old concrete rarely meet the luminance contrast. Once TGSIs become soiled with road grime over time this contrast is greatly reduced.

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Luminance contrast = 26% NOTE still not the required 30%

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Luminance contrast = 23%

THE REALITY
Until such a time that TGSIs are positioned correctly and the correct colour contrast is used, people suffering with a vision impairment will be hesitant to trust them.