In 2000, the Federal Highway Administration (FHWA) and the American Association of State Highway and Transportation Officials (AASHTO) sponsored an international scan on the topic of roadway lighting. One of the topics covered in the international scan was roundabout lighting design practices. At the same time, the FHWA was actively promoting the use of roundabout intersections in the United States based on their safety and operational benefits. On return from the international scan, it was observed that there were a wide variety of practices with regard to roundabout lighting and that there was not a uniform understanding about what the recommended design practice should be. In response to this the Illuminating Engineering Society of North America (IESNA) Roadway Lighting Committee created a subcommittee to examine this issue and develop design guidelines for roundabout lighting. The authors of this paper are both members of the subcommittee. The current study was initiated in support of the IESNA effort in order gather information on the specific practices for lighting roundabouts in the United States and to obtain a better quantitative understanding of what constitutes a well lit roundabout in order to assist the IESNA in developing practical guidelines. The study evaluates the lighting at four roundabout sites with different levels of lighting and different lighting configurations. In addition to assessing general visibility criteria, the project examined overall roadway and pedestrian visibility. Various methods for collecting data are described and computer modeling results are presented.
Samenvatting