LED roadway lighting. Volume 2, Field evaluations and software comparisons

The use of light-emitting diodes (LEDs) for roadway lighting can potentially save energy costs and reduce the frequency of maintenance. The objective of this study is to explore the current state of the art in LED roadway lighting technology. Three sets of LED roadway luminaires, along with a set of high-pressure sodium (HPS) luminaires, were selected for field testing. The LED luminaires were manufactured by GE Lighting (Evolve Series, 454239), Relume Lighting (Vue Series, 320-HE), and Cooper Lighting (Ventus Series, VSTA 08). There was generally fair agreement between illuminance measured in the field and data obtained using the lighting analysis software AGi32, except for one of the LEDs. Results showed that the field data and software results for two of the three sets of LED luminaires satisfied the IDOT illuminance design criteria for the test site conditions for a major roadway with medium pedestrian conflict. On the other hand, one of the sets satisfied the average maintained illuminance criterion for low pedestrian conflicts but not for medium pedestrian conflicts. Likewise, the field data for the HPS luminaire did not meet one of the illuminance uniformity criteria (average/minimum) in the test site conditions. Regarding luminance, measurements were collected in the field using a meter that provided accurate average values but not point-by-point maximum and minimum readings, given the greater aperture angle compared to that suggested by LM-50-99. Results from the field showed that the HPS and all three models of LED luminaires met the average IDOT luminance design criteria for the test site conditions (except one luminaire that met only the requirements in the center span). Software results also showed that the LED luminaires mostly satisfied the average luminance criterion for the specified roadway. However, one of the uniformity requirements (maximum/minimum) was not met by two of the LED sets, exceeding the recommended ratios. Lastly, a generic cost-benefit analysis of an LED luminaire was conducted as an example to analyze LED luminaires. A second phase of this project is proposed, including conducting more detailed cycle-life cost analysis for LED roadway luminaires, determining appropriate light loss factors, providing further information for a new IDOT specification, and examining other technologies such as ceramic metal halide, plasma, and induction.