Human Factors Guidelines for Road Systems 2021 Update, Volume 2: Conduct of Research Report (2022)

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1 SECTION 1: INTRODUCTION A number of existing guides, standards, and references are available to facilitate safe roadway design and operational decisions, including the American Association of State Highway and Transportation Officials (AASHTO) Green Book (AASHTO, 2018), the Manual on Uniform Traffic Control Devices (MUTCD; FHWA, 2012), and the Highway Safety Manual (HSM; AASHTO, 2010). However, these materials often lack a substantive presentation and discussion of human factors principles and concepts that could be used by highway designers and traffic engineers to improve roadway design and traffic safety. Despite a widespread acknowledgment that traffic safety reflects the consideration and integration of three components—the roadway user, the vehicle, and the roadway environment—the information needs, limitations, and capabilities of roadway users are often neglected in traditional resources used by practitioners. In short, existing references applicable to road system design have limitations in providing planners, highway designers, operations staff, and traffic engineers with adequate guidance for incorporating road user needs, limitations, and capabilities when dealing with design and operational issues. In response to this need, the National Cooperative Highway Research Program (NCHRP) initiated a series of projects to develop a new resource document for highway designers, traffic engineers, and other practitioners: Human Factors Guidelines for Road Systems (HFG). The HFG is intended to: (1) serve as a resource document for highway designers, traffic engineers, and other practitioners, (2) provide the best factual information and insight on road users’ characteristics, and (3) facilitate safe roadway design and operational decisions. Published in 2012, NCHRP Report 600: Human Factors Guidelines for Road Systems, Second Edition (Campbell et al., 2012) is the first complete holistic release of the HFG Second Edition (HFG2). The HFG is a relatively new roadway design resource that provides data and insights from the scientific literature on the needs, capabilities, and limitations of road users, including: perception and effects of visual demands, cognition and its influence of expectances on driving behavior, and individual differences such as age and other factors. The current HFG has 21 guideline chapters and 90 guidelines. The HFG assists practitioners in safety, operations, and design in developing a greater understanding of road users’ capabilities and limitations and how these issues could be incorporated into day-to-day decision-making. The objectives of the current project (NCHRP 17-80) were to: (1) prepare an HFG Third Edition based on updated and expanded guidelines, (2) synthesize and incorporate relevant ongoing and completed research, related documents, and user feedback in order to expand the scope and quality of the HFG to increase application and improve usability, (3) employ a format and design similar to the HFG2 (while considering and implementing, as appropriate, modifications to format and style or design). This report summarizes the activities and results associated with Task 9: Develop and Submit Final Third Edition HFG and Additional Deliverables. The purpose of Task 9 was to describe how the project was conducted and describe the new and updated guidelines, which were delivered in a separate document. The body of this report contains four technical sections that

2 document the objectives, methods, and findings of NCHRP 17-80 and summarizes the HFG3 deliverable: ■ Section 1 provides an introduction to this report and the overall project. ■ Section 2 summarizes the objectives, methods, and results of Tasks 1 through 5 (Project Management, Conduct Kickoff Meeting, Identify Necessary Revisions in Existing HFG, Develop and Implement a User Feedback Plan, Conduct Initial Literature Review to Identify Potential Guideline Content, respectively). ■ Conclusions and Recommendations from Tasks 3, 4, and 5, which formed the basis for the Task 6 Work Plan as reported in the Task 7 Interim Report. ■ Section 3 summarizes the objective, methods, and results of the Task 8 efforts to prepare the draft HFG3 and accompanying deliverables.