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.
Phase I: Data collection and analysis
Task 1 Literature Review
The research team shall conduct a comprehensive review of relevant domestic and international research, guidelines, and current documented practices to ascertain the
lighting strategies, technologies, and systems in use and the implications of these on visibility safety as well as the impacts to the wellbeing of travelers, the public, and
environment. The review will identify the pros and cons of different lighting strategies against potential impacts to specific resources, mitigation strategies and will examine
potential performance methods, measures, and indicators for evaluating different lighting strategies.
The sources of literature should be comprehensive and include other NCHRP and industry research, documented agency guidelines and practices relative to decision making on the
application of different lighting strategies, technologies, and systems.
A literature review report shall be created that lists the literature consulted and summarizes the contents of the literature and information gained.
Deliverable: Literature review report
Task 2 State of Practice Stakeholder Engagement
The research team will conduct stakeholder engagement to supplement data collected through the literature review focused on the current state of practice relative to the
identification and implementation of different lighting strategies, technologies, and systems. The research team shall prepare a stakeholder engagement plan for the purposes of
obtaining information on the state of practice by state DOTs and other industry representatives and stakeholders of highway lighting decisions. This plan will be
submitted to NCHRP and the project panel for review and comment. The project team will also provide the Institutional Review Board (IRB) approval/exemption process for
the engagement plan.
Deliverables: Draft engagement plan and state-of-practice technical memo
Task 3 Analyze Data
The research team will analyze and organize the data and information collected to date into a report of the appropriate available data and practices to analyze for the guide. The
data will naturally break down into several areas of research and practice.
The analysis will specifically seek to identify areas in need of further investigation and testing in Phase II as well as specific gaps in knowledge and practice that can be
addressed in the final guide and tool. It will also generate a list of at least 20 case study test sites demonstrating a diversity in contexts like rural, urban, adjacency to sensitive
receptors, the nature and extent of pedestrian and bicyclist use, and other functional characteristics that are considered key to determining context. The team will map out the contextual influences of each of the test sites identified and present them to NCHRP and the project panel for discussion and approval.
The project team will hold 1 to 3 virtual peer discussion groups with 8 to 10 experts each to obtain an industry perspective and early input on the potential contents and utility of a
tool which will be considered for inclusion within the final deliverables. These peer discussion groups will identify what kind of tool(s) and other information would be useful for the guide for practitioners seeking to develop and implement a context appropriate lighting strategy that fully considers safety and the environment.
The research team shall develop a specific plan for convening the virtual peer discussion groups, including participant lists, contents, and format the discussions.
Deliverables: List of test sites with specific characteristics of interest identified; Peer discussion group plan; Peer discussion group meeting(s) held and results documented
Task 4 Develop Workplan
The research team will develop a detailed Phase II work plan that specifies an exact process for the validation of the guide and tools using the data and information collected
in Phase I. A framework for the guide and tool will be used that builds on the industry needs and interests identified in previous tasks. The plan will include process for completing 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
Deliverable: Detailed Phase II Workplan
Task 5 Prepare Interim Report
An interim report will be prepared for presentation to NCHRP and the project panel documenting the literature review, data collected, initial assessments, and conclusions
drawn from that data. The research team will meet with the panel either in person or virtually to discuss the next phase of work.
Deliverable: Interim Report
Task 6 Prepare an Outline of the Proposed Guide
Prepare an outline of the proposed guide and any supplemental products proposed as components of the final products of this research.
Phase II: Data refinement and product development
Task 7 Validation / Case Study Development
Pilot tests of case study sites identified in Task 3 will compare the results of tool recommendations with actual roadways where crash data has been documented. The pilot
testing and validation methods and process will be specified in the Work Plan which will become an addendum to the scope of work. The purpose will be to identify potential
inaccuracies or flaws with the tool and guide as anticipated to be developed.
Deliverable: Memorandum documenting the case studies including the testing process, results,
and conclusions drawn from the data collected
Task 8 Prepare Draft and Final Deliverables
The research team shall prepare a draft guide and other proposed products as agreed to in
the approved Phase II work plan.
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: Phase I underway.
