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Roundabouts At A Glance...

Roundabouts are circular intersections that require all entering traffic to yield at entry. Geometric features of a roundabout include channelized approaches, geometric curvature that ensures travel speeds within the roundabout are around 30 mph or less, and diameters usually between 80 to 200 feet. They are designed to be safer and more efficient than a traditional intersection. The geometry creates a low speed (20-30 mph) environment inside the circulatory roadway, as well as at the entry and exit locations. The geometry also prevents high angle crashes such as “T-bone” and left turn angle crashes. Lower angle, low speed crashes tend to be less severe than higher angle, high speed crashes. 


 Understanding Roundabouts

Roundabout Safety
Roundabouts are one of the most effective intersection control treatments available with the added benefit of calming traffic. They limit vehicle speeds to approximately 20 mph and can control vehicle speeds on four roads simultaneously. Roundabouts typically reduce crashes by 40 to 60 percent, reduce injury by 35 to 80 percent and almost completely eliminate incapacitating injury and fatal crashes. Community gateways and main roadways are effective locations for roundabouts as they slow traffic and provide space for an aesthetically pleasing entrance treatment.
Roundabouts vs. Traffic Signals
Roundabouts have proven to be much safer than traffic signals. The projected injury crash rate for roundabouts is half that of traditional signals.
Roundabout Crash Reduction
There are two basic premises in which roundabouts achieve crash reductions and greatly reduce severity on those few crashes that do occur. One is the simple decision making and the second is the low level of conflicts. At a four-way intersection, there are 32 possible conflict points between vehicles, whereas there are only eight at roundabouts.
Modern Roundabouts vs. Traffic Circles
There are many differences between roundabouts and traffic circles. Unlike traffic circles, roundabouts are used on higher volume streets to allocate right of way between competing intersection movements. Traffic circles have a large diameter, which contributes to high circulating speeds; roundabouts have a smaller diameter, promoting low circulating speeds. Roundabouts have lower entry speeds compared to traffic circles and feature a yield at every entry point, promoting low speed and no weaving.
Driving Modern Roundabouts
Research shows that drivers quickly adapt to the roundabout traffic flow. For instance, Vail and Avon, Colorado, both feature many high capacity roundabouts and are major tourist destinations with thousands of first-time roundabout drivers using the roundabout intersections each year. Despite large numbers of drivers who have not driven roundabouts previously, these intersections work well and do not confuse motorists. Proper use of signing and road striping at roundabouts assists motorists and minimizes the potential for confusion.
Click this link for more information regarding the implementation of Rural Roundabouts!

 Upcoming Projects


​The following roundabout projects in District 8 are currently in some phase of design or development. Costs shown here include design, right of way (as needed) and construction, and due to variables through the planning phase, all schedules and estimates are subject to change. For those projects which are in the public involvement phase, information is available online by clicking the Project Identification Number (PID) assigned to the project below, and additional information regarding the individual projects may be obtained by contacting District 8's Public Information Office.


102059 BUT-73-13.05 ​At the intersection of SR 73 and CR 24 (Jacksonburg Road), just west of Trenton. ​Summer 2020 - Summer 2021 ​$4.5 million
​110466 ​BUT-127-16.56 ​At the intersection of US 127 and SR 73 (Trenton-Oxford Road) in Milford Township. ​Winter 2022 - Fall 2022 ​$2.5 million
109350 ​CLI-73-2.66 ​At the intersection of SR 73 and SR 380, just
east of the I-71 interchange.
​Spring 2022 - Fall 2022 ​$2.45 million
​110462 ​WAR-123-4.69 ​At the intersection of SR 123 and SR 132 in the community of Blackhawk. Winter 2023-Winter 2024 ​$3 million





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