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FHWA logo. FHWA Office of Safety Logo: Safe Roads for a Safer Future, Investment in roadway safety saves lives.

Photograph of two cars wrecked in a crash.

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speaker notes:

This presentation is on the safety aspects of the modern roundabout. It covers the following topics:




slide 2

Terminology

Diagram indicates that roundabouts, rotaries, neighborhood traffic circles, and others are subsets of circular intersections.

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slide 3

What isn't a Modern Roundabout?

Three photos indicate that rotaries, traffic circles, and neighborhood circles are not modern roundabouts.

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Clockwise from upper left:



slide 4

What is a Modern Roundabout?

Photo depicts a roundabout in which traffic flows counter-clockwise around a circular center island, entering traffic yields, and approaches are channelized. A pathway is drawn to indicate the curving through lane and arrows indicate a counter-clockwise traffic movement around the circular center island.

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These four points are what differentiate a modern roundabout from other similar or related traffic control features. Use mouse clicks to bring up each point along with an illustration on the photograph:



slide 5

What is a Modern Roundabout?

Photo illustrating a high-speed rotary that is about 600 feet across.

Photo illustrating a high-speed rotary with a new roundabout and associated roadways being constructed in the center. The new center island is only about 120 to 250 feet across.


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slide 6

Key Features


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slide 7

Key Features

Two photos, one of a yield on the approach to a roundabout, the other an aerial view of a roundabout with arrows overlaid to indicate the counter-clockwise flow of traffic.


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slide 8

Key Features

Photo of a roundabout with lines overlayed to highlight the curvature of the roadway around the circular center of the roundabout.

Photo of a roundabout with landscaping in the center and splitter islands.

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slide 9

Key Features

Three photos, two showing different shaped splitter islands and the third showing a circular center island with a truck apron.


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slide 10

Pedestrian Access

Two photos of brick paved pedestrian walkways set well back from the yield line and containing cutouts for curb access at both the sidewalk and splitter island segments of the crosswalk.


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slide 11

Signing and Marking

Collage of signs and road markings including yield signs and pavement markings, signs warning of a roundabout ahead, a sign indicating a 20 mph speed limit in the roundabout, and a sign providing drivers with information on which path to take off the roundabout to reach which arterials, interstates, or destinations.

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slide 12

Why a Roundabout?


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slide 13

Vehicle Conflict Points

Two diagrams, one of a roundabout and the other of a traditional intersection, showing the locations of vehicle conflict points. The roundabout diagram shows zero crossing points, 4 diverging points, and 4 converging points where conflicts may occur. The traditional intersection diagram shows 16 crossing points, 8 diverging points, and 8 converging points where conflicts may occur.


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slide 14

Vehicle-Pedestrian Conflict Points

Two diagrams, one of a roundabout and the other of a traditional intersection, showing the locations of pedestrian conflict points. The roundabout diagram shows 8 crossing points, and the traditional intersection diagram shows 16 crossing points where pedestrian conflicts may occur.

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slide 15

Type of Crashes

Two diagrams of typical 4-leg intersections, one showing an angle crash and the other showing a left turn crash due to failure to stop or yield.Diagram of a roundabout showing a sideswipe type crash from a vehicle failing to yield before entering the roundabout.


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slide 16

Study Results


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slide 17

Save Money

Photo of a signal equipment box with a red bar across the front indicating 'no signal equipment box.'


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slide 18

Complement Community Values

Photo of a landscaped roundabout replete with palm trees, flowers, and a fountain in the center island.

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slide 19

Special Considerations

Two photos, one of a bicyclist traveling in the right lane of a roundabout, the other of a pedestrian crossing a street at a well-marked pedestrian crosswalk.

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slide 20

Multi-Lane Roundabouts

Photo of a complex roundabout with four roadways converging to create a two-lane roundabout.

Photo of a very complex double roundabout where six roadways converge to create a two-lane roundabout adjacent to a three-lane roundabout. The roundabouts separated by a separator island.

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slide 21

Rural Roundabouts

Two photos of rural roundabouts. One photo shows the juncture of 4 roadways at the roundabout, the other shows a T-intersection with a roundabout at the junction. Both contain splitter islands.

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slide 22

Right-of-Way Requirements

Two 'before' photos of traditional intersections prior to having roundabouts installed, one in a neighborhood the other in an urban center.Two 'after' photos showing the layout of urban and suburban intersections after the application of roundabouts.

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slide 23

Where to Consider Roundabouts


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slide 24

Roundabouts in Corridors

Aerial photo of a corridor containing three consecutive roundabouts.

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slide 25

Roundabouts in Interchanges

Two photos of roundabouts at highway interchanges.

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slide 26

Roundabouts and Driveways

Aerial photo of a neighborhood roundabout characterized by driveways on the adjacent roads leading into the roundabout.

Photo of a neighborhood roundabout with driveways letting out into the roundabout.


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slide 27

Roundabout Resistance

Graph shows about 65 percent of respondents in a public opinion poll about roundabouts felt negative or very negative, whereas after construction about 70 percent of respondents felt positive or very positive about roundabouts.

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slide 28

Keys to Success

Photo of a front lawn with a sign displayed that says 'No Roundabouts.'

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slide 29

Roundabout Resources

Colage of cover art from roundabout resource documents.


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From left to right:



slide 30

For More Information


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Page last modified on May 2, 2017
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