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PIARC (World Road Association), founded in 1909 and comprising 125 member governments from all over the world, is the global forum for exchange of knowledge and experience on roads, road transport policies and practices. With consultative status to the Economic and Social Council of the United Nations, the Association is contributing to a stable and sustainable global development of the road and transport sector.

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Term of the Road Dictionary

coefficient of retroreflected luminance

  • Language : PIARC Road Dictionary / English
  • Theme : Roads Road Equipment Road Lighting
  • Definition : Ratio of the luminance of a field and the illuminance of a plane perpendicular to the illumination direction at that field, for observation and illumination directions close to each other and both forming grazing angles with the road surface [CEN].

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