rural roundabouts an international perspective · transportation seminar, spring 2007 january 12,...

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Hillary Isebrands, P.E.

Iowa State UniversityCenter for Transportation Research and Education

Rural Roundabouts: An International Perspective

Photo Credits: Isebrands unless otherwise notedPaola, KS

Iowa State UniversityTransportation Seminar, Spring 2007

January 12, 2007

o Traffic Circles – 1905

o Modern Roundabout – UK 1960’s

o Europe

o Midwest – 1990’s

Kingston, NY Source: McCulloch

History of Circular Intersections

Modern Roundabouts

Source: Roundabouts: An Informational Guide, FHWA, 2000

o Reduction in crash severity

o Speed reduction

o Improved capacity

o Reduction in queues and delays

o Reduction in emissions

o Maintenance costs lower

o Aestheticso Suitable for most

locations and traffic volumes

o Traffic calming

Benefits of Modern Roundabouts

Paola, KS

o Crash Reduction in the US (Persaud et al, 2001)

o 23 Intersections

o All crashes - 40%

o Injury Crashes - 80%

o Consistent with internationally studies

Safety

Operations

Safety

Rural Urban

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United Kingdom

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France

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France

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France

Italy

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United States

States Actively Implementing Rural Roundabouts

Source: NE Roundabouts

Kansas DOT

Paola, KS

Paola, KS Paola, KS

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Paola, KS Garnett, KS

Minnesota DOT

New Prague, MN

State Highway 13 and County Rd 2 - Scott County, MN

Source: FHWA/MnDOT

Medford, MN Rising Sun, MD

Maryland DOT

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Rising Sun, MDRising Sun, MD Rising Sun, MD

Rising Sun, MDHarford County, MD

Lothian, MD Lothian, MDLothian, MD

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Lothian, MD

Verboot, OR

Washington County Oregon

Washington DOT

Duvall, WA Duvall, WA

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Duvall, WA Duvall, WA

1 Maycock and Hall, “Accidents at 4-arm Roundabouts” 19842 WSDOT Accident Records and WSDOT Traffic Counts3 Projections from RODEL Ltd.Source: Washington DOT

19.1916.522.540.13ProjectedRoundabout3

13,700192.262.329.90.0Novelty Hill Road,Existing2

20,400851.539.211.80.56Signals45-55 mph2

27,8001128.724.73.80.19Roundabouts50–70 mph1

AverageDaily Traffic

Number ofSites

TotalSlightSeriousFatal

Injury Accidents per 100 Million VehiclesCategory

Injury Accident Statistics High-Speed Roundabouts vs. High-Speed Signals

Duvall, WA Source: WA DOT

Discussion/Questions

Hillary N. Isebrands

hillaryi@iastate.edu

Thank You

Gratzie

Merci

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