BACKGROUND

Many state departments of transportation (DOTs) and other agencies use warrants to define the need for roadway lighting. In the United States, lighting warrants are found in the AASHTO Roadway Lighting Design Guide (RLDG), while the primary Canadian resource is the Transportation Association of Canada (TAC) Guide for the Design of Roadway Lighting. Although the AASHTO RLDG is currently in its seventh edition, the warranting system included within the RLDG has not changed significantly from its development in the early 1980s. Since then, there has been recent development of active safety systems in vehicles, solid-state lighting (SSL), and the implementation of the use of crash modification factors (CMFs) in roadway safety analysis.

Currently, the RLDG does not address safety-based alternatives to roadway lighting (e.g., retroreflective pavement marking and roadside delineators) or address the cost/benefit of roadway lighting as a safety measure as compared to other safety alternatives, resulting in inconsistency as to where and when roadway lighting is applied. Further, there is a growing concern about balancing the safety benefits of roadway lighting while aiming to reduce potential environmental impacts, such as energy use and impacts to wildlife.

To assist state DOTs with the identification and selection of appropriate roadway lighting applications, research is needed to develop updated warrants that provide consistency with respect to how roadway lighting is applied as a safety countermeasure.

OBJECTIVE

The objective of this research is to (1) develop updated lighting warrants that consider the latest lighting and traffic engineering practices with an emphasis on safety and (2) evaluate the justification for lighting considering alternative safety treatments, environmental factors, and safety impacts on new lighting technologies and vehicle technologies.

Accomplishment of the project objective will require at least the following tasks.

TASKS

PHASE I – Planning and Data Collection

Task 1. Conduct a literature review of relevant research related to warrants for roadway lighting. The review shall include published and unpublished research conducted through the NCHRP; Federal Highway Administration (FHWA); and other national, international, state, and pooled-fund-sponsored research.

Task 2. Propose a methodical approach (e.g., surveys, targeted interviews, focus groups, and other appropriate methods and/or tools) to collect information and current state-of-practice from state DOTs, practitioners, and relevant stakeholders as it relates to warrants for roadway lighting.

Task 3. Execute the approved Task 2 methodology. Synthesize the results to prioritize knowledge gaps of warrants for roadway lighting. These knowledge gaps should be addressed in this research or in the recommended future research as budget permits.

Task 4. Identify existing sections of the RLDG that the research results may influence or may be affected by the research results, including an update of current glossary of standard terminologies and applications.

Task 5. Propose a preliminary framework to achieve the research objective to be fully developed in Phase II. At a minimum, the proposed framework shall address the following: 

• Identify types of roadway segments, intersections, and interchanges for different geometric, environmental, and operational conditions for lighting warrants. Consider different scenarios including:
  • Bike/pedestrian paths adjacent to roadways;
  • Activity-based demands from community requests (i.e., sports stadiums, community centers, etc.); and
  • Different land use types (i.e., urban-core, urban, suburban, rural, etc.).
• Investigate existing CMFs when determining lighting warrants;
• Evaluate continuous, partial, intersection-based, and delineation lighting conditions as they relate to warrants; 
• List the effects of pedestrian activities, traffic volume, and posted speed limits/operating speed; and
• Examine the effects of the following as they relate to justification for lighting after warrants are determined including:
  • The cost/benefit of roadway lighting as a safety measure as compared to other safety alternatives;
  • Lighting controls and modern vehicle technology; and
  • Lighting as it relates to environmental factors (i.e., flora/fauna, dark skies, light trespass, etc.). 

Task 6. Develop resources from the findings of Task 3 to highlight potential implementation requirements, procedures (including quality assurance (QA)), strategies, and challenges as it relates to light-emitting diode (LED) applications in traffic control devices.

Task 7. Prepare Interim Report No. 1 that documents Tasks 1 through 6 and provides an updated work plan for the remainder of the research. The updated plan must describe the process and rationale for the work proposed for Phases II and III.

PHASE II – AASHTO Deliverable Development

Task 8. Execute the approved Task 5 framework according to the approved Interim Report No. 1.

Task 9. Prepare draft language for consideration by AASHTO in the next update of the AASHTO RLDG, hereafter called the AASHTO Deliverable, supported by examples. The AASHTO Deliverable should be suitable for easy adoption as an appendix to the AASHTO RLDG.

Task 10. Prepare Interim Report No. 2 that documents Tasks 8 and 9 and provides an updated work plan for the remainder of the project. This report should include examples of materials and resources developed in Task 6 to be incorporated into the contractor’s final research report. The updated plan must describe the work proposed for Phase III.

PHASE III – Final Products

Task 11. Present AASHTO Deliverable to the AASHTO Joint Technical Committee on Roadway Lighting for comments and propose any revisions to NCHRP. Revise the AASHTO Deliverable considering the NCHRP’s review comments.

Task 12. Prepare a final deliverable that documents the entire research effort. Final deliverables should include, at a minimum (1) the AASHTO Deliverable; (2) prioritized recommendations for future research; (3) presentation material and resources; and (4) technical memorandum on implementation.

STATUS: Research in progress.