Human Factors Guidelines for Road Systems, Proposed 4th Edition

State departments of transportation (DOTs) and other agencies are seeking to implement data-driven, performance-based processes to improve the planning, design, construction, and operation of multimodal transportation systems. Improvements within these project stages require a range of tools to aid understanding of factors contributing to crashes, identification of relevant countermeasures, and implementation of selected solutions. The tools should ensure that all factors related to crashes are considered during project scoping. Historically, the design and operation of road facilities have not adequately accounted for the interaction between road users and the facilities, particularly users who are most vulnerable to crashes. Behavioral factors should be considered by all involved in the planning, design, construction, and operation of multimodal transportation systems.   NCHRP Report 600: Human Factors Guidelines for Road Systems, Second Edition (HFG2), is a tool for integrating road user characteristics into road design and operational decisions. The HFG2 provides human factors (HF) principles and findings for consideration by highway designers, traffic engineers, and other safety practitioners. Since publication of the HFG2, significant research has been completed that adds additional tools and design guidelines for enhancing road user safety. Practitioner needs have developed as well, and research needs have been identified on additional topics, e.g., improving practitioner knowledge of how bicycle and pedestrian behavior at roundabouts affect operations, and the potential impact of these interactions on innovative intersection designs in general. Other potential research topics include aging road users, road diets, complete streets, applying human factors in countermeasure selection, road safety audits, road signage reviews, determination of crash-contributing factors, and root cause analysis. Finally, once research has addressed these topics, training for practitioners on the application of human factors needs to be developed.   NCHRP Project 17-80, “Expansion of Human Factors Guidelines for Road Systems, Second Edition” is currently in progress and addresses HF considerations for bicycle facilities, pedestrian facilities, and roundabouts. This research identified critical gaps in guidelines for considering human factors. It is expected to be published in late 2020 as the Human Factors Guidelines for Road Systems, Third Edition (HFG3).   The HFG, Fourth Edition (HFG4) is intended to supplement the AASHTO Highway Safety Manual (HSM) with other safety tools and processes such as road safety audits, operational reviews, performance planning, and crash data analysis for road system design and operations. Using the “safe systems” approach, roads are designed and operated to reduce the risk of crashes occurring and, if crashes do occur, to reduce the severity of injuries. A safe systems approach seeks to design infrastructures that recognize and accommodate user capabilities for all types of road facilities. HFG4 guidelines will document the best available HF and road/user interaction research and practices in road safety analyses and design to optimize data-driven safety analysis and decision making.   The objective of this research is to prepare a proposed Human Factors Guidelines for Road Systems, Fourth Edition (HFG4), which can be used to by state DOTs and other transportation agencies to integrate HF principles into design and operations across roadway systems for all road users. For this research, road users may include, but not be limited to, drivers, pedestrians, bicyclists, motorcyclists, and electric scooter users.


  • English


  • Status: Active
  • Funding: $550000
  • Contract Numbers:

    Project 22-46

  • Sponsor Organizations:

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001

    American Association of State Highway and Transportation Officials (AASHTO)

    444 North Capitol Street, NW
    Washington, DC  United States  20001

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Project Managers:

    Jared, David

  • Performing Organizations:


    Bellevue, WA  United States 
  • Principal Investigators:

    Campbell, John L

  • Start Date: 20210601
  • Expected Completion Date: 20240930
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01707551
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 22-46
  • Files: TRB, RIP
  • Created Date: Jun 5 2019 1:06PM