Proposed UK guidance for lighting in residential roads

This paper reports a proposed new system for specifying illuminances and lamp types for equal visual effects at mesopic illuminances, developed within the mesopic lighting panel of the Institution of Lighting Professionals in the UK. This study is applied in residential streets and thus the visual tasks considered are those relevant for pedestrians. It is proposed that the benchmark lamp for residential streets in the UK is the low-pressure sodium lamp; if other types of lamps are used, and these have a CIE General Colour Rendering Index of R-a >= 60, then the average illuminance can be reduced by an amount that is determined using the new CIE system for mesopic photometry and is dependent on the scotopic/photopic ratio of the lamp.