Roundabouts
Roundabouts are circular intersections. Roundabouts reduce traffic conflicts (for example, left turns) that are frequent causes of crashes at traditional intersections. Unlike a traffic circle or a rotary, a roundabout's incoming traffic yields to the circulating traffic.
Crash Types & Causes
- Roundabout Fact Sheet, FHWA, CRT, Corporate Research & Technology [HTML, PDF 68 KB]
Roundabouts are a proven safety solution that prevent and reduce the severity of intersection crashes. Roundabouts are designed to meet the needs of all road users—drivers, pedestrians, pedestrians with disabilities, and bicyclists. A roundabout eliminates some of the conflicting traffic, such as left turns, which cause crashes at traditional intersections. Because roundabout traffic enters or exits only through right turns, the occurrence of severe crashes is substantially reduced.
Technical Implementation & Tools
NCHRP Report 572: Roundabouts in the United States, Transportation Research Board, The National Academies, 2007. [PDF 4.33 MB]
Based on a comprehensive evaluation of roundabouts in the United States, the report presents methods of estimating the safety and operational impacts of roundabouts and updates design criteria for them. The report will be useful to geometric designers and traffic engineers considering improvements to an intersection.Roundabouts: An Informational Guide, FHWA-RD-00-67, June 2000 [HTML, PDF 344 KB]
Pedestrian Access to Roundabouts: Assessment of Motorists’ Yielding to Visually Impaired Pedestrians and Potential Treatments To Improve Access, FHWA-HRT-05-080, May 2006. [HTML, PDF 1.14 MB]
Roundability Accessibility Summit, 2002.
The Roundabout Accessibility Summit brought together stakeholders to address accessibility issues within roundabouts as input to the U.S. Access Board Draft Public Rights of Way Accessibility Guidelines.Attachment 2: Proposed Access Board Guidelines on Roundabouts.
Florida Roundabout Guide [PDF 2.86 MB]
Non-visual gap detection at roundabouts by pedestrians who are blind: A summary of the Baltimore roundabouts study, The Access Board.
Report is a summary of a research project conducted in the Baltimore, Maryland metropolitan area in April, 2000. The study was the first of a series of research projects to be conducted to evaluate access to modern roundabouts by pedestrians who are blind.Pedestrian Access to Modern Roundabouts: Design and Operational Issues for Pedestrians who are Blind, The Access Board.
Research
Active Projects
Investigation and Mitigation of Driver Confusion at Modern Roundabouts
The objectives of this research include: (1) identification of user issues and confusing elements of roundabouts via surveys and development of mitigation measures for safer usage of arterial roundabouts in Nebraska; and (2) development of a criteria matrix for arterial intersections that NDOR can use to check the candidacy of intersections for conversion to single-or multi-lane roundabouts.
Start date: 2006/7/1; End date: 2008/6/30; Status: Active
Contract/Grant Number: P598
Source Organization: Nebraska Department of RoadsUpdate of Roundabouts: An Informational Guide
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 non-motorized 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. The objective of this project is 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).
Start date: 2006/10/12; Status: Proposed
Source Organization: National Cooperative Highway Research Program
Resources
Related Website Links
Operational and Safety Performance of Modern Roundabouts and Other Intersection Types.
Roundabouts: Pedestrian Safety Guidance and Countermeasures Selection System.
NYSDOT Guidance for Roundabout Users: Motor Vehicles, Pedestrians, and Bicycles.
Publications
- State Resources
Kansas Roundabout Guide. A Supplement to FHWA’s Roundabouts: An Informational Guide, October 2003 [PDF 17.71 MB]
Guide is a supplement to the FHWA document, Roundabouts: An Informational Guide, FHWA-RD-00-067. 2000.A Citizen’s Guide to Roundabouts. (NYSDOT) [PDF 15.26 MB]
Interim Reports and (Design) Guidance. (NYSDOT) June 30, 2000. [PDF 136 KB)
Example Plan Sheets for Typical Single Lane Roundabout. (NYSDOT)
Photograph of Fish Hook Pavement Markings on Approach. (NYSDOT)
Photograph of View from Multilane Approach Yield Line. (NYSDOT)
Rodel 1 Interactive Roundabout Design. (NYSDOT) [PDF 1.31 MB]
RODEL is a fully interactive software program for aiding roundabout design.-
Roundabouts - A Safer Choice (brochure), FHWA-SA-08-006, 2008, FHWA [HTML, PDF 619 KB]
Training
- One-day Roundabout Workshop, FHWA-NHI-380091
