17-69

backing board (of a traffic control device)

surround or extension to traffic control device used for the reasons listed below:

- to improve conspicuity of a sign by increasing its size and isolating it from its background;

- to improve conspicuity of a sign by virtue of the colour of the backing board;

- to reduce the effects of glare when the sun is low and behind the sign

Equivalent term: "backboard"

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