Evaluation of glare and lighting performance in nighttime highway construction projects

In the first task of the project, a comprehensive literature review was conducted to study the latest research and developments on veiling luminance ratio (glare) and its effects on drivers and construction workers during nighttime highway construction work. Sources of information included publications from professional societies, journal articles, on-line databases, and contacts from DOT’s. The second task involved site visits to a number of nighttime work zones to identify practical factors that affect the measurement of the veiling luminance ratio in nighttime construction sites. The site visits were conducted over a five-month period in order to gather data on the type of construction operations that are typically performed during nighttime hours, the type of lighting equipment used to illuminate the work area, and the levels of glare experienced by workers and motorists in and around the work zone. One of the main findings of these site visits was identifying a number of challenges and practical factors that significantly affect the measurement and quantification of the veiling luminance ratio (glare) in nighttime work zones. These practical factors were carefully considered during the development of the glare measurement model in this study to ensure its practicality and ease of use in nighttime work zones by resident engineers and contractors alike. Another important finding of the site visits was the observation that improper utilization and setup of construction lighting equipment may cause significant levels of glare for construction workers and drive-by motorists. In the third task, field experiments were conducted to study and evaluate the levels of lighting glare caused by commonly used lighting equipment in nighttime work zones. During these experiments, a total of 25 different lighting arrangements were tested over a period of 33 days from May 10, 2007 to June 12, 2007 at the Illinois Center for Transportation (ICT) in the University of Illinois at Urbana-Champaign. The objectives of these experiments were to: (1) analyze and compare the levels of glare and lighting performance generated by typical lighting arrangements in nighttime highway construction; and (2) provide practical recommendations for lighting arrangements to reduce and control lighting glare in and around nighttime work zones. The field tests were designed to evaluate the levels of glare and lighting performance generated by commonly used construction lighting equipment, including one balloon light, two balloon lights, three balloon lights, one light tower and one Nite Lite. The tests were also designed to study the impact of tested lighting parameters (i.e. , type of light, height of light, aiming and rotation angles of light towers, and height of vehicle/observer) on the veiling luminance ratio experienced by drive-by motorists as well as their impact on the average horizontal illuminance and lighting uniformity ratio in the work area. Based on the findings from these tests, a number of practical recommendations were provided to control and reduce veiling luminance ratio/glare in and around nighttime work zones. The final (fourth) task of this study focused on the development of a practical model to measure and quantify veiling luminance ratio (glare) experienced by drive-by motorists in lanes adjacent to nighttime work zones. The model was designed to consider the practical factors that were identified during the site visits, including the need to provide a robust balance between practicality and accuracy to ensure that it can be efficiently and effectively used by resident engineers on nighttime highway construction sites. To ensure practicality, the model enables resident engineers to measure the required vertical illuminance data in safe locations inside the work zone while allowing the traffic in adjacent lanes to flow uninterrupted. These measurements can then be analyzed by newly developed regression models to accurately calculate the vertical illuminance values experienced by drivers from which the veiling luminanc ratio (glare) can be derived. This task also analyzed existing recommendations on the maximum allowable levels of veiling luminance ratio (glare) that can be tolerated by nighttime drivers from various lighting sources, including roadway lighting, headlights of opposite traffic vehicles, and lighting equipment in nighttime work zones. (Abstract shortened by UMI. )