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

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10 SECTION 3: PLANNING AND DEVELOPING THE DRAFT THIRD EDITION HFG The outcomes from Tasks 3, 4, and 5 were used to develop a work plan for developing the HFG3, which guided the guideline development process and activities. This section summarizes the development of the work plan and the subsequent new chapters and chapter updates that comprise the HFG3. Task 6: Develop a Work Plan for Developing the HFG3 The objective of Task 6 was to develop a work plan for developing the HFG3, which was is centered around two primary instruments: (1) Annotated Outlines for the new, high-priority chapters, and (2) summary tables for likely updates to existing chapters and for lower priority new chapters. The annotated outlines summarize key data sources and research findings that are subsequently used to develop guidelines. Because there were too many references to develop full, structured document reviews or annotated outlines for all research sources in all chapters, the project team focused on developing annotated outlines for the three, highest-priority new chapters. The team also performed less rigorous—but nevertheless comprehensive—reviews of abstracts for candidate sources to update the existing chapters. The annotated outlines and full descriptions of the methodologies used to develop them are described in the Task 7 Interim Report. Because it was not feasible to address all the chapters in the HFG, the general approach outlined in the work plan was to develop the high-priority new chapters and existing chapter updates first and then develop lower priority chapters opportunistically (i.e., as time and budget allowed). These chapters included: New Chapters: ■ Bicyclists ■ Pedestrians ■ Roundabouts ■ Tutorials Summary of HFG Topics ■ Tutorial: Using the HFG to Support Road Safety Audits ■ Tutorial: Joint Use of the HSM and HFG ■ Tutorial: Using the HFIM to Conduct Diagnostic Assessments ■ Lower priority chapters as time and budget allow Existing Chapter Updates: ■ Chapter 1: Why Have Human Factors Guidelines for Road Systems? ■ Chapter 2: How to Use This Document ■ Chapter 3: Finding Information Like a Road User ■ Chapter 5: Sight Distance ■ Chapter 10: Non-Signalized Intersections

11 ■ Chapter 11: Signalized Intersections ■ Chapter 17: Speed Perception, Speed Choice, and Speed Control ■ Lower priority chapter updates as time and budget allow Task 7: Develop and Submit Interim Report At mid-project, an interim report was developed describing project activities to date. The Task 7 Interim Report included: ■ Slides from the kickoff meeting in Task 2 – including notes and action items discussed at the meeting. ■ A list of errors (including inconsistencies & duplications), gaps, and modifications to the current HFG text, reflecting the Task 3 review and the results of the Task 4 user feedback summary. ■ User feedback summary from Task 4 – including, a summary of the methods and findings from the Task 4 user feedback activities, as well as our conclusions regarding key criteria to be considered and detailed acceptance criteria for the new/updated content to be included in the HFG3. ■ Results of the initial literature review in Task 5 – including, search results, source tables and literature summaries of key topics. ■ A work plan for developing the HFG3. The work plan included descriptions of information available for new chapters and for updating existing chapters, annotated outlines for existing chapters, expectations for guidelines to be included in each chapter, priorities for chapter development, and other relevant information. Task 8: Develop and Submit Draft HFG3 and Additional Deliverables The objective for Task 8 was to develop new materials and update existing guidelines as outlined in the work plan. New and Updated Chapters and Tutorials A detailed review of each source identified in the annotated outlines literature was conducted, and the annotated outlines were expanded into full guidelines where the information was sufficiently available. Additional topics identified during the in-depth reviews were also included as new guidelines where appropriate. The three highest-priority new chapters—Bicyclists, Pedestrians, and Roundabouts—were developed first, with plans to develop the Older Road Users chapter if time and budget allowed. Existing chapter updates were accomplished using similar methods. Documents relevant to the existing guidelines in the chapter were reviewed to identify new information about existing topics, whether supporting or contrary to the information in the existing guideline. Relevant guidelines were modified to represent the new or updated information. Also, new guidelines within a chapter were identified and written for new themes found in the literature that had enough supporting information.

12 The following new chapters and guidelines were completed: ■ Bicyclists  Signals and Signal Timing for Bicycles at Intersections  Markings for Bicycles at Intersections  Bicycle Lanes  Separated Bicycle Lanes  Contraflow Bicycle Lanes  Shared Use Lanes  Shared Bus-Bicycle Lanes  Mitigating Heavy Vehicle Conflicts with Bicycles ■ Pedestrians  Task Analysis of Pedestrian Crossing In a Multiple-Threat Scenario  Countermeasures to Reduce Pedestrian Exposure to Vehicles at Crossings  Speed-Calming Countermeasures at Crosswalks  Improving Pedestrian Visibility and Conspicuity at Crosswalks  Selecting Beacons to Improve Pedestrian Conspicuity at Crosswalks  Influence of the Built Environment on Pedestrian Crossing Safety  Design Challenges for Older Pedestrians  Pedestrian Rail Crossing Safety  Key References for Pedestrian Crossing Safety Countermeasures ■ Roundabouts  Reducing Vehicle Speeds Approaching Roundabouts  Increasing Driver Yielding Rates for Pedestrians at Roundabouts  Guide Signing at Roundabouts  Accommodations for Bicyclists at Roundabouts  Countermeasures for Improving Accessibility for Visually Impaired Pedestrians at Roundabouts  Roundabout Lighting The following existing chapters were updated: ■ Chapter 1: Why Have Human Factors Guidelines for Road Systems? ■ Chapter 5: Sight Distance  Key Components of Sight Distance  Determining Stopping Sight Distance  Determining Intersection Sight Distance

13  Determining When to Use Decision Sight Distance  Determining Passing Sight Distance  Influence of Speed On Sight Distance  Key References for Sight Distance Information  Where to Find Sight Distance Information for Intersections ■ Chapter 10: Non-Signalized Intersections  Acceptable Gap Distance  Left-Turn Lanes at Non-Signalized Intersections (new guideline)  Sight Distance at Left-Skewed Intersections  Sight Distance at Right-Skewed Intersections  Countermeasures for Improving Accessibility for Vision-Impaired Pedestrians at Roundabouts (moved to new Roundabouts chapter and updated) The following new tutorials were completed ■ Tutorial: Joint Use of the HSM and HFG ■ Tutorial: Using the HFG to Support Road Safety Audits ■ Tutorial: Summary of HFG Topics Planned vs. Accomplished Some chapters were either significantly changed from the annotated outlines presented in the work plan or were not included in the draft HFG3. ■ Pedestrians. The amount of information available regarding roadway design for pedestrians is substantial; consequently, the five planned guidelines were expanded to include nine guidelines in the chapter. ■ Older Road Users. This new chapter was not developed due to time and budget limitations. Nevertheless, the new Pedestrians chapter contains guidance for accommodating older pedestrians. ■ Chapter 2: How to Use This Document. This chapter was not updated. No substantive information was found to support any changes to the chapter. ■ Chapter 3: Finding Information Like a Road User. This chapter was not updated per instruction from TRB. ■ Chapter 11: Signalized Intersections. This chapter was not updated due to time and budget limitations. ■ Chapter 17: Speed Perception, Speed Choice, and Speed Control. This chapter was not updated due to time and budget limitations. ■ Tutorial: Using the HFIM to Conduct Diagnostic Assessments. This was not included as a separate tutorial. Rather, the information planned for this tutorial was included in the Using the HFG to Support Road Safety Audits.

14 Challenges Two primary challenges were associated with accomplishing project goals. The first challenge was related to updating existing guidelines. Many of the existing guidelines nearly or completely fill the two-pages allowed for that guideline, which precludes adding any substantive amount of information to the guideline. In general, it was found that the existing information is still relevant, and removing some information to accommodate other new information either diluted the guideline or otherwise did not enhance the guideline. One solution to overcoming this limitation is to split a guideline into two separate guidelines, either with new themes comprising the new guideline or in some other logical fashion. Another challenge was related to preparing the HFG3 for publication. The original project plan was to provide a fully complete, new edition of the HFG, with updated the page numbers, references, links, and other elements. The original source for the HFG2, however, was not available in editable form, and conversion from Adobe PDF produced documents that would take substantial editing. To complicate matters, logical document flow would require the new chapters to be inserted into different sections of the HFG, requiring renumbering the chapter numbers. Such renumbering would require all of the cross references in the document to be re- created. The available schedule and budget did not support the level of effort required to do the work. Consequently, the HFG3 was developed as an addendum to the HFG2, with the intent of creating a fully formed edition in a subsequent project. Recommendations for Future Guidelines The following chapters and topics are recommended for future development. Planned Chapters Deferred for Future Development ■ New Chapter: Older Road Users. Either create a new chapter or update existing chapters with relevant information ■ New Chapter: Complete Streets/Context Sensitive Design ■ Chapter 6: Curves ■ Chapter 11: Signalized Intersections ■ Chapter 17: Speed Perception, Speed Choice, & Speed Control ■ Chapter 20: Markings ■ Chapter 21: Lighting Potential Future/Additional Guidelines for New and Updated Chapters The following guidelines were identified during development of the Pedestrians, Bicyclists, and Roundabouts chapters, but were not included due to time and budget constraints. Pedestrians: ■ Traffic Control Treatments and Devices for Pedestrians ■ When to use Marked vs. Unmarked Crosswalks

15 ■ Leading Pedestrian Interval (include in the Signalized Intersection) ■ Bus Stops Bicyclists ■ Design Countermeasures for Bicyclist Visibility ■ Lighting for Bicyclist Visibility. Possibly update the Characteristics of Lighting That Enhance Pedestrian Visibility guideline in Chapter 21 to include bicyclists as well as pedestrians Roundabouts ■ Heavy Trucks in Roundabouts ■ Special Considerations for Urban Environments ■ Channelized Right Turn Lanes. This topic was identified opportunistically while developing the Pedestrians chapter