Most research show a positive safety impact of lighting at rural intersections. Adding lighting therefore becomes an important safety countermeasure at isolated rural intersections. Due to factors such as the lack of design guidelines and concerns about the associated costs and maintenance requirements, lighting practices for rural intersections vary significantly among different states. A number of roadway lighting guides are available nationwide, among which are the American Association of State Highway and Transportation Officials (AASHTO) Roadway Lighting Design Guide and the Illuminating Engineering Society of North America (IES) Roadway Lighting standard. However, these guides contain limited information on rural intersection lighting.
The objective of this synthesis is to document current rural lighting design and application practices employed by state departments of transportation. The study focus on when states add lighting to rural intersections, what types of lighting can be most efficiently used, how lighting metrics (e.g., illuminance levels, correlated color temperature, and lighting distribution) is determined to yield the most safety benefits while reducing costs, and what low-cost technological and design solutions are suitable for rural intersection lighting.
Information to be gathered includes, but is not limited to:
• Current rural lighting design and application practices used by DOTs
• Types of lighting used by DOTs in rural intersections
• Selection criteria used for lighting in rural intersections
• How lighting metrics are determined to yield the most safety benefits while reducing costs
• Low-cost technological and design solutions being used by DOTs for rural intersections
• DOT State DOT policies, particularly cost-sharing and cost-reimbursement policies, influence the decision to add or exclude lighting
• Use of solar-powered systems and under what circumstances are they used
Information will be collected through literature review, survey of DOTs, and follow-up interviews with selected agencies for the development of case examples. Information gaps and suggestions for research to address those gaps will be identified.
• Bhagavathula, R., R. Gibbons, and C. Edwards. Relationship Between Roadway Illuminance Level and Nighttime Rural Intersection Safety. Transportation Research Record 2485, 8–15.
• Isebrands, H., S. Hallmark, Z. Hans, and T. McDonald. Safety Impacts of Street Lighting at Isolated Rural Intersections. Report MN/RC-2006-35, Center for Transportation Research and Education, Iowa State University, September 2006.