BACKGROUND
Roadway lighting is a common countermeasure used to increase visibility at night or in poor weather conditions, and may offer substantial safety benefits for all road users. With the advent of light emitting diode (LED) and adaptive roadway lighting systems, lighting characteristics can be adjusted as a function of need as well as to control for unintended effects. These systems are believed to provide effective safety performance potentially at a lower cost and energy requirements compared with traditional lighting systems.
Decisions regarding the appropriate level of light to provide a given freeway, highway rest area or interchange, or urban streetscape are dependent upon localized characteristics, climate, and other circumstances. What may seem like the ideal quantity of light to support the safety of vehicular users may be less beneficial or even harmful to vulnerable road users, the environment, or community groups. Furthermore, the qualities of light, such as the color, intensity, uniformity, or degree of glare may also impact safety outcomes for all users. This creates a need to strike an appropriate balance to maximize safety benefits while controlling for and avoiding harmful impacts.
While the American Association of State Highway and Transportation Officials (AASHTO) Highway Safety Manual and other literature provide guidelines to support decisions on the appropriate application of light for different contexts, the industry seeks more robust information and analysis tools to assist in decision-making about the appropriate quantity and quality of light for different environments, contexts, and purposes. Considerations of the different uses and effects of lighting in rural, urban, and suburban contexts are desired, as well as lighting targeted to highway facilities such as rest areas and interchanges. The research will not compare or recommend proprietary lighting products or systems for a given application.
OBJECTIVE
The objective of this research is to develop a guide for state departments of transportation (DOTs) seeking direction on the appropriate quantity and quality of overhead light for a given highway. This would include considerations of fixed, adaptable, continuous, or targeted lighting with respect to a given highway or site.
In preparing this guide, the research should identify all potential issues and considerations for evaluation by state DOTs in planning for and installing overhead lighting on highways. The guide shall at a minimum contain the following components:
1. A literature review on the science and application of overhead highway lighting in consideration of different contexts (e.g., urban, rural, and suburban highways) and other significant considerations such as time of day and weather;
2. A state of practice summary and analysis of the methods, tools, and techniques in use by state DOTs and other agencies for evaluating the effects of alternative lighting plans on a given project;
3. A set of procedures, tools, and techniques for use by state (DOTs) to identify and evaluate the potential benefits and costs of alternative lighting plans for a given project;
4. A process diagram flowchart or decision tree that outlines how and when to analyze and select light plans for a given project; and
5. Case studies that illustrate the decision-making and application of a variety of lighting plans for highway projects located in diverse contexts, including at least one rural and one urban example.
These resources may be compiled into a single comprehensive guide document or provided as separate deliverables.
Anticipated final deliverables will include: (1) a guide with supplemental tools and products as defined in an approved Phase II work plan; (2) a Conduct of Research report focused on the research process, methods, and data collected from the research conducted; and (3) an implementation of research plan or report.
STATUS: Contract underway.
