Measurement of pavement surface reflectance for a balloon lighting system

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Nighttime construction offers many advantages to the public and to state agencies. Under these conditions, traffic is minimal and construction operations can be conducted effectively and quickly. In addition, cooler temperatures are favorable for the equipment and the material being installed. Despite these advantages, controlling glare is a critical and important issue in adequately lighting highway work zones. One of the controlling parameters in glare calculation is the pavement luminance, which is a quantitative measure of the surface brightness. Pavement luminance is based on predefined parameters known as r values provided by the Illuminating Engineering Society of North America (IESNA) for four standard pavement surfaces in the r tables. With the recent introduction of balloon lighting system for construction applications, the objective of this study was to measure pavement reflectance characteristics for this system in the laboratory and to compare the results to the standard r tables. For this purpose, a laboratory experimental setup was developed. On average, measured r values were 20% greater than the IESNA standard values for concrete surfaces (R1), 84% greater for R2 standard surfaces, and 95% greater for R3 standard surfaces. An analysis of variance statistical analysis indicated that the differences between the measured r values and standard r tables were not significant for concrete surfaces but were statistically significant for asphalt road surfaces. This was attributed to the weathering of the road samples used in this study, to the shorter towers used with balloon lights, and to major changes in asphalt construction practices and mix ingredients in the past 30 years. Recommendations based on the results of this study are presented. © 2008 ASCE.

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Journal of Transportation Engineering

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