roundabout practices: highlights from nchrp...
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Roundabout Practices: Highlights from NCHRP Synthesis 488Mid‐Colonial District Institute of Transportation EngineersAnnual Conference
April 18, 2016
Session 4B: Policies and GuidanceAlek Pochowski, AICP, PE
Presentation OverviewPresentation Overview
Historical perspective
Policies and Outreach
Survey Results
Case Examples
Best Practices
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Historical PerspectiveHistorical Perspective
Traffic circles existed around the world prior to 1906The first one‐way circle was Columbus Circle in New York City in 1906Early circles evolved into rotaries in the United States, and fell out of favorInternationally, roundabouts flourished The first roundabout in the United States was constructed in Summerlin, Nevada in 1990Maryland’s roundabout program made the continuing construction of roundabouts possible New York Public Library
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NCHRP Synthesis 264, published in 1998NCHRP Synthesis 264, published in 1998
In 1998: Nine states had a roundabout in
operation, under construction, or in design
1/3 of states without roundabouts were considering roundabouts
By 2010, all 50 states and DC have a roundabout in operation38 of the 40 states surveyed in 2015 have a roundabout in operation on the state system
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Roundabout PoliciesRoundabout Policies
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OutreachOutreach
Negative perception is a major impediment to the construction of roundaboutsAfter construction, perception tends to become positiveWebsites, brochures, flyers, videos, and coloring books have been usedRoundabouts have been incorporated in driver’s manuals
Indiana Drivers Manual 6
Survey ResultsSurvey Results
Basic information
Selection
Costs
Outreach
Performance
Design
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Year State Agency Build Their First Roundabout
Total Reported Number of RoundaboutsTotal Reported Number of Roundabouts
State Total Mini‐Roundabouts
Total Single‐Lane
Roundabouts
Total Multilane
Roundabouts
Total Roundabouts
Delaware 1 11 1 13
Maryland 10 114 37 161
Pennsylvania 0 20 1 21
Virginia ‐‐ 145 15 160
West Virginia 0 5 4 9
United States Total 94 2,250 660 3,044
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Roundabout SelectionRoundabout Selection
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Roundabout CostsRoundabout Costs
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State Mini‐Roundabout Single‐Lane Roundabout
Multilane Roundabout
Delaware $2,000,000
Maryland $400,000 $1,000,000 $2,500,000
Pennsylvania
Virginia $1,500,000 $2,500,000
West Virginia $400,000 $600,000
Roundabout OutreachRoundabout Outreach
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State Website Flyer/Pamphlet Video
Delaware Yes Yes Yes
Maryland Yes Yes
Pennsylvania Yes Yes
Virginia Yes Yes Yes
West Virginia Yes Yes Yes
Number of state agencies developing types of public
outreach material as reported by state agency.
DE, PA, WV use HCM; VA uses Sidra with EF, MD uses HCM and Sidra
DE, MD, VA, WV use HSM; PA uses CMFs or CRFs
Roundabout Operational and Safety PerformanceRoundabout Operational and Safety PerformanceOperational Performance Models Reported as Used by State Agencies
Safety Analysis Procedures Reported as Used by State Agencies
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Phased ImplementationPhased Implementation
YesMarylandVirginiaWest Virginia
NoDelawarePennsylvania
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Known leaders in the roundabout fieldA mix of early adopter and more recent adoption statesA geographic mix of statesPreference given to panel member statesPreference given to states who have participated in similar interviews in the past to allow for a comparative review.
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Case ExamplesCase Examples
Roundabout selectionPhased roundabout implementationModifications to existing roundaboutsDesign vehicle accommodationsAccelerated low‐cost roundabouts
Largely drive by safety and policy directives
California ExampleCaltrans and Intersection Control Evaluations (ICE) Must consider signal, yield and multi‐way stop control during or
before completion of the project initiation phase of the project development process.
The safety performance characteristics must be considered in the development of engineering and investment recommendations.
The authority to recommend or approve the use of yield‐controlled roundabouts is delegated to the Districts.
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Roundabout SelectionRoundabout Selection
Phased Roundabout ImplementationPhased Roundabout Implementation
Phased implementation approach is entirely safety drivenFive of seven states interviewed have modified roundabouts by reducing capacityAll seven DOTs are now actively attempting to size their roundabouts for immediate and near‐future vehicle demandMost states use a 20‐year design lifeStates will open roundabouts with fewer lanes if the configuration will be sufficient for a certain number of years
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Phased Roundabout ImplementationPhased Roundabout Implementation
Goo
gle Earth Ae
rial
Goo
gle Earth Ae
rial
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Accelerated Low‐Cost RoundaboutsAccelerated Low‐Cost Roundabouts
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Georgia $63,000 roundabout installed over several weekends Several others installed for ~$300,000Washington Four roundabouts all installed in a weekend $200,000 to $300,000 eachMaryland $50,000 75‐ft diameter roundabout installed at US 50 and Thompson Creek
Road in Stevensville, Maryland in 2007 Used only thermoplastic pavement markings
19Scott Zehngraff
20Scott Zehngraff
21Scott Zehngraff
22Scott Zehngraff
US‐50/Thompson Creek in Stevensville, MarylandUS‐50/Thompson Creek in Stevensville, Maryland
Pete Jenior
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Best PracticesBest Practices
Safety is the primary driver in the selection of roundabouts
Consider roundabouts early in the process and on equal footing with other traffic control options
Don’t overbuild roundabouts
Identify barriers to implementation and consider alternative construction techniques
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Thank YouThank You
Alek Pochowski, AICP, PEKittelson & Associates, Inc.Washington, [email protected]
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