An exposition of a road lighting model to facilitate simple estimation of road surface illuminance parameters for conventional system specifications and recommendations for retrofitting of luminaires

Commissioning, maintenance and revamping of energy-efficient, economical and controllable road lighting systems that satisfactorily cater to the visual requirements of pedestrians and motorists are preferable in the wake of the current global energy crisis. Installation of new road lighting systems or retrofitting of the existing ones would require careful consideration of the design configurations that would maintain road surface average illuminance, uniformity of illuminance, and diversity of illuminance levels in accordance with applicable regional, national, or international standards and guidelines. To facilitate rapid approximation of pertinent road surface illuminance parameters with a view of the prevailing road lighting practices involving common heuristic configurations, photometric simulations of road lighting were conducted in a created software model with photometric data tables of high-pressure sodium (HPS) and light-emitting diode (LED) luminaires possessing different power ratings for a specified set of luminaire mounting height, road width, pole spacing, overhang and tilt values, and a mathematical model consisting of six equations derived by multiple linear regression was propounded (coefficient of determination > 0.90) with relevant predictor variables. Moreover, a framework for LED luminaire power rating selection for retrofitting operations was proposed to assist manufacturers, electrical contractors and utility operators entrusted with such work.