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Roundabouts

The Virginia Experience

Purpose of Briefing

• Background on Roundabouts

• How they pertain to Virginia

• Definition & Operational Characteristics

• Roundabouts Vs. Traffic signals

• Considerations for Roundabouts

• Review Process

Misconceptions

• Roundabouts have been around forever

• Roundabouts are unsafe to Pedestrians and Bicyclists

• The public avoids using Roundabouts

• They are unsafe next to schools

1900’s - 1940’s Rotaries and Traffic Circles Used

1950’s Circular Intersections fell out of favor

1963 Great Britain redesigns the Circular

Intersection

1980’s “Modern Roundabout” used throughout

Europe and Australia

1990’s “Modern Roundabout” utilized in the U.S.

» More than 1000 now built in U.S.

» Over 300 more to be built this year alone

Circular Intersection History U.S. Modern Roundabout HistoryU.S. Modern Roundabout HistoryU.S. Modern Roundabout HistoryU.S. Modern Roundabout History

1990 First Modern Roundabout in Nevada

1992 Florida’s first Modern Roundabout

1993 Maryland’s first Modern Roundabout

1995 Vermont’s first Modern Roundabout

2000 New York’s first Modern Roundabout

2004 Pennsylvania’s first Modern Roundabout

2004 New Jersey’s first Modern Roundabout

2004 Delaware’s first Modern Roundabout

2004 Virginia’s first Modern Roundabout

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Leading Roundabout States

Colorado > 150

Washington > 95

Utah > 90

Oregon > 50

Florida > 40

Kansas > 35

California & Nevada > 20 each

North Carolina > 15

New York > 18

What Is a Roundabout?

• A circular intersection joining

two or more streets

• All turns are to the right

• The SAFEST at-grade intersection

Not a RoundaboutDifferences Between Roundabouts and Circles / Rotaries

• Yield at the approach

• Vehicle Deflection

• Splitter Island to control speeds

Is a Roundabout the Right Tool ?

• History of Accidents

• High proportionate of left turns

• Irregular Geometrics

• Vehicle Queues

• Less expensive means of control

• Sufficient Right-of-Way

Operational Comparison of

Roundabouts Vs. Signals

• Enhanced safety • Intersection efficiency – traffic

moves• Potential air quality benefits• Lower cost to build & operate• Fuel Savings• Improved aesthetics• U-turns are allowed

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Vehicle-Vehicle Crossing Conflicts

Signalized Intersection

Diverging 8

Merging 8

Crossing 16

Total 32

Roundabout Design

Diverging 4Merging 4Crossing 0Total 8

INSURANCE INSTITUTE FOR

HIGHWAY SAFETY

CRASH REDUCTIONS FOLLOWING INSTALLATION OF ROUNDABOUTS IN THE UNITED STATES – MARCH 2000

• Reduction of Total Crashes by 39%

• Reduction of Injury Crashes by 76%

• Reduction of Fatal and Incapacitating Crashes by 89%

On the web at: www.highwaysafety.org

Safety Benefits

Based on 15 Single Lane Roundabouts in Maryland in 2004

• Fatal Crashes down 100 percent

• Total crash rate down 60 percent

• Injury crash rate down 82 percent

• Property damage down 27 percent

Construction Time

DEPENDING ON THE TECHNIQUES USED, IT MAY TAKE FROM THREE WEEKS TO THREE MONTHS TO COMPLETE CONSTRUCTION OF A ROUNDABOUT

Special Considerations/Concerns

• Public Acceptance

• Driver Inexperience

• Pedestrians / ADA concerns

• Bicycles

• Emergency vehicles

• Lighting Concerns

• Right of Way requirements

Public Attitude Toward Roundabouts -

Before and After Construction

Attitude Before After

Construction Construction

Very Negative 23% 00%

Negative 45% 00%

Neutral 18% 27%

Positive 14% 41%

Very Positive 0% 32%

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Public Involvement

• Public resistance is common

• Before construction: 2 to 1 against roundabout

• Education is crucial

• After construction: 3 to 1 in favor of roundabout

• Visualizations & traffic simulations are very helpful

Community Acceptance

Main Vail - Diamond Interchange $2M (8,200 vph)

Community Acceptance

Vail, CO Constructed Oct. 1995

Voted Best Public Works Project

5 Years Straight

Public Opinion WILL Change

The director of the Charles R. Wood Theater said she was skeptical when the Greenwich roundabout was first talked about.

"I'm not an expert on traffic, but I was convinced it wasn't going to work out," she said.

Now, she describes driving through the circular intersection as an “awesome” experience.

"I guess sometimes you just have to trust the opinions of traffic experts," she said.

Pedestrian Consideration

Benefits:• Easy to determine gaps

• Cars only coming from one direction

• Fewer lanes to cross

• Splitter Island provides refuge

• Slower Speeds

Trade Offs:• Must assess gaps

• No protected phase ? ? ?

Unless “All Red” Signals Provide No

“Protected” Pedestrian Phase

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SUMMARY-Why Safer for Pedestrians?

Much lower number of conflict points. – Because all vehicles travel the same direction in a roundabout, the

number of vehicle/pedestrian conflict points is much lower than at intersections controlled by traffic signals.

Vehicles [are forced] to approach and travel through slowly.

– This maximizes the time that pedestrians and motorists have to avoid conflicts.

Non-attentive driving eliminated.– For example, vehicle/pedestrian crashes that occur when motorists run

red lights and ignore stop signs do not happen at roundabout intersections. The horizontal curvature of the roundabout forces drivers to pay attention to their surroundings as they approach and passthrough the intersections.

Pedestrian exposure to traffic is much lower.

2003 Legislative Action

House Joint Resolution 594…….

Resolved, That the Department of Transportation be encouraged to construct more roundabouts instead of signalized intersections;

“Roundabouts;

An Informational Guide”

FHWA Document Publication FHWA Document Publication

Number RDNumber RD--0000--067067

““SIDRASIDRA”” SoftwareSoftware

Used to determine Used to determine

feasibility, appropriate feasibility, appropriate

geometric configuration and geometric configuration and

functional capabilities in functional capabilities in

regards to volumes and level regards to volumes and level

of service.of service.

Roundabout Informational Pamphlet

Roundabouts in Virginia

Why Use a Roundabout?

How to Drive Roundabouts

Review and Approval Process

• District

Existing & Proposed Subdivisions

Secondary System – up to Design

Volume of 10,000 VPD

• Roundabout Review Committee

Secondary System – over

10,000 VPD

All Urban and Primary Systems

Items the Committee Reviews

• Approach Grades and sight distances

• All Geometrics

• Pedestrian crossing locations

• Pavement markings

• Signing

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Items the Committee Reviews

• Roadway Lighting (desirable)

• Nearest entrance locations and nature of property use

• Initial or present and projected design year traffic counts on all approaches

• Turning movements for all directions

When to Submit

• Early on, as soon as the preliminary plans are completed or a proposed site is selected.

• The Committee will assist the Districts in their review when asked.

Review Time

• Typical, allow two weeks for the Committee’s review.

ROAD DESIGN MANUAL

The information that we have mentioned today regarding the Roundabout Approval Process and the Data to be Submitted for Review will be included in the July 2006 Revision of the Road Design Manual.

Roundabouts in Virginia

Charlottesville Airport

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Gloucester Powhatan Courthouse

City of Richmond Christopher Newport

Va Tech Campus Town of Amherst

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Amherst Circle 1940 Plan Sheetamherst.jpg (882 KB)

amherst.jpg (882 KB) Gordonsville Circle

Roundabouts – Yes or No

Moving

Virginia

We Keep

Roundabout Review Committee

Terry Knouse, PE - Location & Design

Steve Edwards – Traffic Engineering

Walter Pribble – Transportation & Mobility Planning

QUESTIONS

? ?Roundabouts

The Virginia Experience