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.
| Software Packages |
|---|
| SIDRA |
| RODEL |
| VISSIM |
| Highway Capacity (HCS) |
| ARCADY |
Roundabouts have demonstrated substantial safety and operational benefits compared to other forms of intersection control, with reductions in fatal and injury crashes of 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 cognitive impairments.
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
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