Insights

Roundabouts are continually evolving as transportation engineers develop configurations that address different operational, safety and site-related challenges. 

Turbo roundabouts are among the newer configurations attracting attention in North America. They use spiral lane geometry and lane dividers to guide drivers into the correct lane before entry and discourage lane changes within the roundabout. By keeping vehicles in defined paths, the design can reduce weaving and some conflicts found at conventional multilane roundabouts. 

However, turbo roundabouts are only one tool in a much larger design toolbox. The key is not choosing the newest configuration but identifying the solution that best fits the site-specific challenges at hand.

Roundabout Configurations and Design Strategies

Whether the goal is reducing specific crash issues, accommodating higher traffic volumes, producing less delay, reducing speeds or addressing site constraints, different roundabout types offer different solutions.

Single-lane Roundabouts 

Single-lane roundabouts are among the most widely used roundabout configurations in the United States. Featuring a single circulating lane, they are commonly used in rural, suburban and urban settings where improving safety and traffic flow are primary objectives.

Compact and Mini Roundabouts 

Compact and mini roundabouts are smaller modern roundabouts designed to conserve space and reduce costs. They are commonly used where right-of-way, cost, speed or community context makes a larger roundabout impractical while still providing many of the safety and operational benefits of a traditional roundabout.

Multilane Roundabouts 

Multilane roundabouts feature two or more circulating lanes and are designed to accommodate higher traffic volumes than a single-lane configuration. They are often used on major corridors, at larger intersections and in areas where traffic volumes are expected to increase.