Roadway Lighting Design Methodology and Evaluation

Theoretical methods are usually performed for ideal conditions to determine the illuminance and luminance but other design limitations should be considered in the real world. Also the visibility level is calculated by using background and target luminance under ideal conditions. In reality, there are many factors, which are very difficult to predict and include in lighting design equation. Human eye is also a complex device it is difficult to accurately design an outdoor illumination system just simply based on numerous theoretical assumptions. RP-8 is using for theoretical calculation of light distribution on pavement. This calculation method needs to include some correction constant for parameters such as pavement is not level, maintenance for cleaning, aging lamps lamp reflector and refractor is not centered, lamp is off center and tilted, pole is not vertical to the pavement, voltage fluctuation, photodetectors response, ambient temperature factors, reliability of illuminaires, roads crowned, and superelevation.