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Roundabouts

      The modern roundabout is a type of circular intersection defined by the basic operational principle of entering traffic yielding to vehicles on the circulatory roadway. Roundabouts have geometric features providing a reduced speed environment that offers substantial safety advantages and excellent operational performance.  Roundabouts shall be considered as an alternative for all intersections that are being reconstructed, including those where a traffic signal is being proposed. 

      View Roundabout Guidance Manual

       


      Notice

      Announcements

      Roundabouts Coming to Riverside Drive at I-285 in North Fulton

      February 4, 2016

      Georgia DOT has begun a safety enhancement project in Sandy Springs to build roundabouts at both ramp intersections of the I-285 interchange at Riverside Drive. The newly designed $5.6 million interchange will convert the existing signalized ramp intersections to single lane roundabouts.

      Construction TimeframeBegin TimeEnd Time
      Weeknights9PM5AM
      Weekends8PM10AM

      Roundabout Analysis Tool 3.1

      The Georgia DOT Roundabout Analysis Tool is to be used for preliminary design and planning purposes only. As an analysis tool, it provides useful measures such as capacity, queue, and delay by which its operational ability can be assessed. As a design tool, it allows the designer to quickly gauge initial geometric constraints (single lane, multilane, bypass lanes, etc.), that could not be known without some level of traffic analysis. The Roundabout Analysis Tool is most useful when determining the feasibility of a roundabout at an intersection and should accompany any preliminary study. In addition to this tool, there are many software packages available for use, namely RODEL and SIDRA.

      Download Analysis Tool


      Software Packages
      SIDRA
      RODEL
      VISSIM
      Highway Capacity (HCS)
      ARCADY
      Article Author Date Media
      Roundabouts: The Surprising Facts About A Misunderstood Intersection Kate Sweeney September 24, 2015 WABE 90.1 FM
      What's at the Intersection of Traffic and Planning? Roundabouts Andria Simmons August 23, 2015 Atlanta Journal Constitution

      Roundabouts have demonstrated substantial safety and operational benefits compared to other forms of intersection control, with reductions in fatal and injury crashes of from 60-87 percent. The benefits apply to roundabouts in urban and rural areas and freeway interchange ramp terminals under a wide range of traffic conditions. Although the safety of all-way stop control is comparable to roundabouts, roundabouts provide much greater capacity and operational benefits. Roundabouts can be an effective tool for managing speed and transitioning traffic form a high speed to a low speed environment. Proper site selection and channelization for motorist, bicyclists, and pedestrians are essential to making roundabouts accessible to all users. In particular, it is important to ensure safe accommodation of bicyclists at higher speed roundabouts and for pedestrians with visual or cogitative impairments.

      Introduction to Roundabouts: Roundabout Planning, Design and Operational Analysis

      Course Description
      In this course, you will review the planning phase of a roundabout, the operational analysis steps, and detailed design guidelines for roundabouts. The planning phase focuses on where roundabouts should be considered and issues inherent in the design and operation. The operational analysis covers the detailed performance of a roundabout and typical measures of effectiveness, such as capacity, delay, and queues. The design phase includes issues related to size, horizontal and vertical alignment, transit, pedestrians, bicyclists, signing, and striping. In addition, you will perform exercises individually and in team settings and apply and discuss the various elements, standards, and features relevant to the development and design of modern roundabouts.

      The basis for the course is the FHWA document, Roundabouts: An Informational Guide, supplements to the FHWA guide prepared for the Kansas DOT and other states, and ongoing instructor involvement in NCHRP research and TRB, ITE, NCUTCD, and IESNA Committees.

      Course Topics

      • Characteristics of early circular intersections and present-day roundabouts
      • Roundabout site selection and planning
      • Effectiveness measures for roundabouts
      • Roundabout design

      If you're interested in attending this course please submit an email with your name and contact information (email and phone) to roundabouts@dot.ga.gov

      Georgia DOT has conducted several presentations regarding roundabouts in Georgia. These presentations provide a general overview of how roundabouts provide a safer alternative for new and existing intersections on federally funded highways. Please choose a presentation from the list below to learn more about the roundabout program.

      Presentation Event Date
      Georgia DOT Roundabout Program 2011 Georgia Transportation Summit November 2011
      Traffic Signals & Roundabouts: An Update of GDOT Changes ITE Summer Seminar July 2010
      Modern Roundabouts in Georgia  ITE September 2009
      Roundabouts: a Safer Intersection Choice GDOT Board Meeting January 2009
      Resource Description
      FHWA Roundabouts Flyer General Info
      FHWA Safety: Roundabouts FHWA’s website that includes a safety review of roundabouts with crash reports, technical tools, research and reports.
      NCHRP Report 672, Roundabouts: An Informational Guide 2nd edition This guide explores the planning, design, construction, maintenance, and operation of roundabouts. The report also addresses issues that may be useful in helping to explain the trade-offs associated with roundabouts.
      NCHRP Report 572 A publication by the Transportation Research Board of National Academies detailing the application of roundabout design and operation with USA specific data.
      How to Use a Roundabout This website has an interactive Roundabout that illustrates step by step maneuvers a motorist in any vehicle driving through a roundabout. This site requires flash.
      Insurance Institute for Highway Safety: Roundabouts The IIHS page has a video describing how roundabouts work, Q&As on roundabouts, and a bibliography of recent IIHS research on roundabouts.
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      Statewide Roundabouts Map

      Please access the map below to view roundabout locations in Georgia.  Use the map control tools to navigate and zoom.


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      Contacts

      Please contact the following if you experience problems accessing the Analysis Tool or have questions regarding Roundabouts:

      Georgia DOT Roundabouts Team
      Office of Traffic Operations
      roundabouts@dot.ga.gov