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Roundabouts in the United States. Module 3 Safety Considerations . Safety benefits of roundabouts . Research has shown there are many safety benefits associated with roundabout intersection design. Safety is a major consideration on our highways and roadways.

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Module 3 Safety Considerations

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Roundabouts in the United States

Module 3Safety Considerations

Safety benefits of roundabouts

Research has shown there are many safety benefits associated with roundabout intersection design.


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Safety is a major consideration on our highways and roadways

In the year 2003 there were an average of 6,850 motor vehicle crashes per day at intersections in the United States.

PHOTOGRAPHY SOURCE: Fred Ranck

For transportation professionals, safety is a major concern.


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Intersections are the scene of many accidents.

PHOTOGRAPHY SOURCE: Fred Ranck

Transportation professionals are always looking for ways to reduce the number and severity of crashes.


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What is the effect on crash rates after an intersection is converted to a roundabout?

Conventional 4-way Intersection

Roundabout

Data from 55 intersections with at least 2 years of crash data before and after conversion of the intersection to a roundabout.


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What is the effect on severe injury rates after an intersection is converted to a roundabout?

Conventional 4-way Intersection

Roundabout

Data from 55 intersections with at least 2 years of crash data before and after conversion of the intersection to a roundabout.


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How do typical types of crashes compare between conventional intersections and roundabouts?

Urban Signalized Intersection

Roundabout


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How do typical types of crashes compare between conventional intersections and roundabouts?

Suburban Signalized Intersection

Roundabout


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How do typical types of crashes compare between conventional intersections and roundabouts?

AWSC intersection

Roundabout


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How do typical types of crashes compare between conventional intersections and roundabouts?

Rural TWSC intersection

Roundabout


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How do typical types of crashes compare between conventional intersections and roundabouts?

Suburban TWSC intersection

Roundabout


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How do typical types of crashes compare between conventional intersections and roundabouts?

Urban TWSC intersection

Roundabout


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Typical types of crashes at roundabouts

Entering


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Typical types of crashes at roundabouts

Exiting


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Typical types of crashes at roundabouts

Examples of Loss of Vehicle Control


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Typical types of crashes at roundabouts


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Bicycle and Pedestrian Considerations

PHOTOGRAPHY SOURCE: Lee Rodegerdts

Intersections also introduce concerns for transportation professionals on the safest way to accommodate pedestrians and cyclists.


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Pedestrian Considerations at Roundabouts

PHOTOGRAPHY SOURCE: Lee Rodegerdts

Data on pedestrian/motor vehicle crashes is very limited.


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How do typical types of pedestrian/motor vehicle crashes compare between conventional intersections and roundabouts?

PHOTOGRAPHY SOURCE: Lee Rodegerdts

Motor vehicles conflict with pedestrians in the crosswalk areas and can occur as the vehicles enter or leave the intersection from several different directions.

A roundabout allows a pedestrian to observe motor vehicles from one direction at a time as they cross the travel lanes.


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Pedestrian Considerations at Roundabouts

  • “Personally, I love them, . . . you only have to stop one lane of traffic, then go to the middle and wait. The cars can’t go much faster than 20 mph through the roundabout so the crossing aspect is great”

    • From the Howard-Suamico—Denise Haltom, School Crossing Guard, Suamico, Wisconsin

PHOTOGRAPHY SOURCE: Lee Rodegerdts


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Bicycle Considerations

PHOTOGRAPHY SOURCE: Lee Rodegerdts


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Cyclist Movements at Roundabouts – Circulating as a Vehicle.

Bikes re-enter bike lane

Fewer conflict points with motor vehicles

Lower motor vehicle speeds (15-20 mph)

Bikes merge with motor vehicles

Bike lanes are not recommended within a roundabout. Instead, cyclists merge with traffic before entering the roundabout, circulate with traffic, and then re-enter the bike lane after exiting.


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Cyclist Movements at Roundabouts – Circulating as a Pedestrian.

Bikes return to bike lane

Bicyclists cross as pedestrians

Bikes join shared path with pedestrians

If a cyclist is uncomfortable riding with traffic, a cyclist can choose to travel instead as a pedestrian.


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Summary of the Safety Features of Roundabouts

  • Travel speeds generally reduced by traffic calming effects

  • In almost all cases, the total number of crashes is reduced when a conventional intersection is replaced with a roundabout

PHOTOGRAPHY SOURCE: Lee Rodegerdts

  • And more importantly, the number of severe injury crashes is dramatically reduced due to the roundabout’s common direction of travel and similar speeds


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