Background and Summary of a Guide for Roundabouts (2023)

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1 Summary RESEARCH REPORT ORGANIZATION The Research Report is organized in the following chapters: • Chapter 1: Background – introduces the original problem statement and project background • Chapter 2: Research Approach – outlines the research activities • Chapter 3: Findings and Application - summarizes the following findings and how this contributed to the Final Guide. o Literature Assembly o Survey of User Feedback o Designing for Trucks Research o Designing for Bicycles Research o Synthesis of External Research o Guide Development • Chapter 4: Conclusions and Suggested Research – provides an overview or key project conclusions and outlines topics that could benefit from additional future research. • Appendices – includes additional project details and findings o Appendix A – Guide Bibliography o Appendix B – Truck and Bicycle Research o Appendix C - Synthesis Summaries PURPOSE The objective of this research was to develop a guide for roundabouts that would serve as the primary source for guidance on roundabouts. The resulting Guide integrates a performance- based design approach, incorporates research, and provides roundabout-specific guidance. FINDINGS AND APPLICATION The project team reviewed relevant literature, including national and state research and guidance documents, and other sources. The team considered the literature when conducting research and developing Guide content. The project team developed an electronic survey regarding the development of the Guide. The survey results provided an opportunity for practitioners to share their experiences and preferences. The purpose of the Designing for Trucks Research was to assess roundabout design decisions for serving large trucks, specifically with respect to using truck cases. For agencies and

2 designers to achieve the desired performance, they must be able to understand the benefits and drawbacks of desired approaches and be able to evaluate their decisions. The Case 2 and Case 3 design approaches are still emerging, and there are few cumulative years of historical, nationwide performance for these designs to have a comparative answer. However, the research tasks conducted for this project have yielded useful findings related to truck cases. The Designing for Bicycles Research resulted in an overview of the bicycle facility design guidance and identified design strategies applicable to roundabouts that are appropriate for the person who is “interested but concerned” in bicycling. As agencies plan for complete networks of bicycle facilities comfortable for people biking of all ages and abilities, bicycle facilities at roundabouts need to be welcoming for people biking at the roadway approaches that intersect at the roundabout. This research resulted in updated bicycle treatment concepts that were integrated into the Guide. The team conducted syntheses summaries for the following eight topics to support the development of the Guide.: • Designing for Oversized/Overweight (OSOW) Trucks • In-Service Assessment and Retrofits of Existing Roundabouts • Mini-Roundabouts • Economic Impact of Roundabouts • Traffic Control Devices – Metering • Traffic Control Devices – Pedestrian Crossings • Traffic Control Devices – Railroad Crossings • Illumination CONCLUSIONS The Guide serves as the primary source for guidance on all aspects of roundabouts. The Guide integrates a performance-based design approach, incorporates research, and provides roundabout-specific guidance.