OBJECTIVE

The objective of this project was to develop a new national guide for development and operation of roundabouts based on the FHWA publication Roundabouts: An Informational Guide (FHWA-RD-00-067).

STATUS

NCHRP Report 672, Roundabouts: An Informational Guide--Second Edition has been published.

BACKGROUND

Many developments have taken place since publication of the FHWA's Roundabouts: An Informational Guide in 2000. Ongoing research (particularly NCHRP Project 3-65, Applying Roundabouts in the United States) will enhance guidelines on operational analysis, design characteristics, and safety analysis of roundabouts. Considering that the Guide has become an authoritative national publication, it would be of great benefit to update this Guide after critically reviewing available information. Furthermore, incorporating new research on nonmotorized users will contribute significantly to improving roundabout applications for pedestrians, bicyclists, and users with special needs (visual and other physical impairments). Some of the areas where revisions might be considered are geometric design (including triple-lane roundabouts); intersection sight distance; speed estimations; lane markings, signing, and other traffic control devices; construction and maintenance; safer accommodations of pedestrians; safety evaluation; access management considerations; applications at ramp terminals or interchanges; and mini-roundabouts.

TASKS

Task 1. Review current roundabout design guides used in the United States and internationally. Review relevant recent literature and ongoing research efforts.

Task 2. Conduct focus groups consisting of U.S. planners, designers, and operators of roundabouts and other interested parties to identify concerns with the FHWA Guide. Candidate participant lists should be submitted to the NCHRP at least 2 weeks before each focus group meets.

Task 3. Critically review Roundabouts: An Informational Guide, identifying areas of weakness and omission. Aspects of the Guide that should be considered include policy considerations; rationale for selection of a roundabout for a particular intersection; planning; traffic and safety analysis procedures; geometric design (including curvature, cross section, and sight distance); treatments for pedestrians, bicycles, and large vehicles; traffic control devices; special considerations for access management, interchange applications, and network impacts; and construction and maintenance considerations.

Task 4. Develop an annotated outline for the new guide that will be developed in Task 7, clearly identifying sources for material for each section.

Task 5. Develop an updated, detailed work plan for developing material for the new guide that is not currently available from other sources. This plan should be consistent with available project resources.

Task 6. Submit an interim report documenting Tasks 1 through 5 for review by the NCHRP.

Task 7. Develop the new guide. The new guide should build on standard industry references such as AASHTO's Geometric Design of Highways and Streets and the Manual on Uniform Traffic Control Devices. Additional graphics representing current designs and illustrating key concepts are needed. The list of references should be organized by chapter.

Task 8. Participate in a meeting with the panel and selected other reviewers to discuss the new guide.

Task 9. Submit a final report that documents the entire research effort and includes the new guide (revised based on the Task 8 meeting and written comments) as a stand-alone document.