A review of design recommendations for P-class road lighting in European and CIE documents - part 1 : parameters for choosing a lighting class

This paper is a discussion of the factors that might be used to establish a suitable light level for subsidiary roads where the target users are pedestrians. The weighting parameters used in the Commission Internationale de l’Eclairage document CIE115:2010 to discriminate between the six levels of the P-series of lighting classes are questioned. Limitations of the weighting parameters include (1) while some of the weighting parameters are associated with pedestrian road traffic collisions, they do not lead to optimal lighting conditions or to predicable relationships, (2) there is no evidence to support the one-class change prompted by a change in level of a weighting parameter nor for the assumed cumulative effect of different weighting parameters, and (3) they do not match the stated purposes of lighting in subsidiary roads. Giving consideration to the situations where evidence indicates a change in light level is warranted, and not assuming that different parameters are cumulative in effect, leads to a three-class system similar to those in the British Standard BS5489-3:1992 and the Illuminating Engineering Society of North America IESNA Design Guide 5:1994.