U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000


Skip to content
Facebook iconYouTube iconTwitter iconFlickr iconLinkedInInstagram

Safety

FHWA Home / Safety / Proven Safety Countermeasures / Roundabouts

Roundabouts

The modern roundabout is an intersection with a circular configuration that safely and efficiently moves traffic. Roundabouts feature channelized, curved approaches that reduce vehicle speed, entry yield control that gives right-of-way to circulating traffic, and counterclockwise flow around a central island that minimizes conflict points. The net result of lower speeds and reduced conflicts at roundabouts is an environment where crashes that cause injury or fatality are substantially reduced.

Illustration: This illustration shows a multilane roundabout. The roundabout has four approach legs. Each approach leg is a four-lane divided highway. Each approach leg yields to circulating traffic within the roundabout and features a high visibility crosswalk. Several pedestrian safety countermeasures are visible, including tactile curb ramps and multiuse path facilities.

Illustration of a multi-lane roundabout. Source: FHWA

Roundabouts are not only a safer type of intersection; they are also efficient in terms of keeping people moving. Even while calming traffic, they can reduce delay and queuing when compared to other intersection alternatives. Furthermore, the lower vehicular speeds and reduced conflict environment can create a more suitable environment for walking and bicycling.

Photo: This photograph shows a single-lane roundabout. Each of the four legs approaching the roundabout is a yield-controlled, two-lane roadway. Each approach leg features a high visibility crosswalk. Raised medians are present in the vicinity of the roundabout but not beyond the extents of the roundabout. The roundabout island appears to be traversable by trucks and other large vehicles.

Example of a single-lane roundabout. Source: FHWA

Roundabouts can be implemented in both urban and rural areas under a wide range of traffic conditions. They can replace signals, two-way stop controls, and all-way stop controls. Roundabouts are an effective option for managing speed and transitioning traffic from high-speed to low-speed environments, such as freeway interchange ramp terminals, and rural intersections along high-speed roads.

Sources

1. AASHTO. The Highway Safety Manual, American Association of State Highway Transportation Professionals, Washington, D.C., (2010).

Safety Benefits:

Two-Way Stop-Controlled Intersection to a Roundabout

 82%

Reduction in fatal
and injury crashes1

Signalized Intersection to a Roundabout

 78%

Reduction in fatal
and injury crashes1

 


Guidance Memos NEW

Read the Guidance Memoranda on Promoting the Implementation of Proven Safety Countermeasures.

2021 | 2017 | 2012 | 2008

Page last modified on October 28, 2021
Safe Roads for a Safer Future - Investment in roadway safety saves lives
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000