2 day Roundabout2 day RoundaboutDesign WorkshopDesign Workshop

Instructor:Howard McCulloch

The DisclaimerThe opinions expressed by

NE ROUNDABOUTS are that ofNE ROUNDABOUTS and not necessarily that of NYSDOT

Roundabout WorkshopModule 1: History, Background & Examples

1900s - 1940s Rotaries and Traffic Circles Used

1950s Circular Intersections fell out of favor

1963 Great Britain redesigns the Circular Intersection

1980s Modern Roundabout used throughout Europe and Australia

1990s Modern Roundabout utilized in the U.S.Greater than 1000 now built in U.S.Over 300 more to be built this year alone

Circular Intersection History

Columbus Circle N.Y.C.

Roundabouts / Traffic Circles

Washington D.C. - Master Plan

Problems w/ Traffic Circles & RotariesA Scene from European Vacation

Traffic Circle vs. RoundaboutMalta Roundabout superimposed on Latham Traffic Circle

Tangential Approach geometry

vs.

Deflected Approach geometry

No European Vacationtype entrapment here

Traffic Circle vs. RoundaboutKingston Traffic Circle Under Construction to become a Roundabout

Traffic Circle vs. RoundaboutJohnson City Traffic Circle becomes Roundabout

Traffic Circle vs. RoundaboutRoundabouts do not have pedestrian facilities to center island

Truck Apron Should NOT Look Like Crosswalk

1990 First Modern Roundabout in Nevada

1992 Floridas first Modern Roundabout

1993 Marylands first Modern Roundabout

1995 Vermonts first Modern Roundabout

2000 New Yorks first Modern Roundabout

2004 Pennsylvanias first Modern Roundabout

2004 Virginias first Modern Roundabout

2004 Delawares first Modern Roundabout

2004 Ohios first Modern Roundabout

U.S. Modern Roundabout History

Colorado > 150Washington > 100Utah > 90 Maryland > 80North Carolina > 40Oregon > 35Florida > 30Kansas > 25California & Nevada > 20 eachNew York at least 16, with > 50 in design

throughout the state

Leading Roundabout States

Kingston 2 laner that replaced traffic circleNorth Haven single laner that was supposed 1 of 2Corning (x2) (2) 2 laners that were done for accessGriffiss 2 laner done in old air force baseRochester single laner on RIT campusLatham 2 laner from a restriped traffic circleGreat Neck single laner that replaced signalized circleVoorheesville single laner that replaced yield YGreenwich single laner that replaced signalized TIthaca single laner done without DOT knowledgePlattsburgh single laner that replaced signalized 4-way

New York Roundabouts

North Haven Long Island

Rome Former Griffiss Air Force Base

Rochester R.I.T. Campus

Great Neck Long Island (as signalized traffic circle)

Great Neck Long Island (as Modern Roundabout)

Great Neck Long Island

Voorheesville Capital District New York

Greenwich Eastern New York

Ithaca Central New York

Plattsburgh Northern New York

Johnson City: In constructionMalta: I-87 exit 12, Rt. 67 Corridor (5)Colonie: Albany Shaker Road @ Maxwell RoadTroy: Rt. 2 @ Pawling AvenueBuffalo Area: Harlem Rd. (3), Hamburg (4)Liberty: I-86 exit 100 (1), Rt. 55 @ Rt. 52 (1)Kinderhook: Rt. 9 @ Rt. 9H, 5 leg roundaboutGlens Falls Area (3) urban roundabouts

New York should average over 15 per year.

Upcoming New York Roundabouts

Roundabout SolutionsI-87 Exit 12 - Malta roundabout corridor

Short Queuing Area

Roundabout SolutionsI-87 Exit 12 - Malta roundabout corridor

Narrow BridgeU-turns / Access Control

Roundabout SolutionsI-87 Exit 12 - Malta roundabout corridor

View at Route 9 and Route 67

Visual Simulation

View of Route 67 at Cemetery

Visual Simulation

View of Route 67 at Malta Commons

Visual Simulation

View of Route 67 at Exit 12 Interchange

Visual Simulation

I-890 & Curry Road Ext. RotterdamA typical cloverleaf weave fix

RochesterThe Peanut

Harlem Rd, Buffalo Single lane opening

Harlem Rd, Buffalo multi lane future

Glens Falls 5 leg urban

South Glens Falls elliptical single lane

Maine (97) & New Hampshire (03) both have a few and are progressing designs

Vermont (95) has around 5 open and a few in the works, used to be the leading NE state

Massachusetts (01) & Rhode Island (02) each have at least 1 built and are looking to have state guidelines developed

Connecticut (95) has 7 or so built and ConnDOT has recently released rough guidelines will only allow single lane designs

Northeastern States Roundabout Status

Mass Transit at Rutgers - NJ

Provided by Gannett Fleming, Inc. and NJ DOT

People Leaving Work at Princeton - NJ

PENN DOT Guide to Roundabouts Publication No. 414 May 2001

Prepared by Michael Baker Jr., Inc. Guidelines for Implementation Excellent Questionnaire 5 Case Studies Comments were provided for Williamsport

where 5 roundabouts were being considered

Roundabout WorkshopModule 2: Safety

Why are Roundabouts Being Considered?

Safest Intersection High Capacity / Low Delay Good for All Modes of Traffic Geometric Flexibility Aesthetics

Top Ten Crash Fatality States

States Actively Progressing Roundabouts

89% reduction in fatalities = approx. 8,500 lives per year51,000 lives on this chart alone

1000+/-

Intersection Related Fatalities

Roundabouts2004 Preconstruction Training Conference

PresenterHoward McCulloch

Roundabout & Intersection Design Specialist

Lloyd RueDesign-traffic-safety Engineer

FHWA Montana

PresenterPresenterHoward McCullochHoward McCulloch

Roundabout & Intersection Design SpecialistRoundabout & Intersection Design Specialist

Lloyd RueLloyd RueDesignDesign--traffictraffic--safety Engineersafety Engineer

FHWA MontanaFHWA Montana

Crash Reduction Shoulder Widening

Widen shoulder from 0-8 ft (FHWA-RD-91-046)

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Crash Reduction Rumble Strips

Rumble strip crash reduction (FHWA-RD-00-032)

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Crash Reduction Turn Lanes

Add major road right turn and left turn lanes at 4-legged urban signalized intersection (FHWA-RD-02-103)

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Crash Reduction - Roundabout

Conversion of existing intersection to small/moderate sized roundabout (FHWA-RD-00-067)

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Safety Impacts of Modern Roundabouts Type of Roundabout

Converted from

# of Conversions

Percent Reduction of all Crashes

Percent Reduction of Injury Crashes

Single Lane, Urban

Stop Controlled

12 69% 80%

Single Lane, Rural

Stop Controlled

9 65% 68%

Multi-lane, Urban

Stop Controlled

7 8% 73%

Urban Signalized 5 37% 75% All 33 47% 72% Source: NYSDOT Study October 2003

The video you are about to see is somewhat graphic. The pedestrian shown in this video does actually

survive. The pedestrian was pronounced dead on the scene, revived

in the ambulance on the way to the hospital, and has made a full recovery.

WARNING

RED LIGHT RUNNING CAMERA

40 MPH T-Bone Crash

INSURANCE INSTITUTE FOR HIGHWAY SAFETY

Reduction of Total Crashes 39% Reduction of Injury Crashes 76% Reduction of Fatal and 89%

Incapacitating Crashes

On the web at: www.highwaysafety.org

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

2004 Safety Data from Maryland DOT

Reduction of Total Crashes by 68%

Reduction of Property Damage Only Crashes by 41%

Reduction of Injury Crashes by 86%

Reduction of Fatal / Incapacitating Crashes by 100%

This resulted in a B/C analysis that indicated for every dollar spent on these projects, considering the 15-year service life of the roundabouts, there is a return of approximately $15.00 to be realized through accident reduction.

Towson, Maryland - Before

Towson, Maryland - After

Montpelier, VT RoundaboutAround 300 from a school

600 children per day

800 pedestrians per day

13,000 vehicles per day

Only 4 reportable crashes in 10 years

injury accidents down 69%

There are now over 40 roundabouts near schools

HOWARD, WISCONSIN

Bicycling has been made safer, and students are now allowed to bike to school. The president of the Bicycle Federation of Wisconsin also believes the roundabouts are safe and convenient for bicyclists and supports their construction throughout the state

Reportable vehicle crashes have virtually disappeared from the two intersections and injuries have been eliminated. This occurred in spite of the introduction of hundreds of inexperienced drivers to Lineville Roads existing traffic load after the new high school opened in August of 2000

The director of the Brown County Sheriffs Departments Patrol Division and the principal of Bay View Middle School both believe that traffic congestion and speeding have been significantly reduced along Lineville Road. The patrol director and principal also believe that safety has been greatly enhanced by the roundabouts.

Semi-trailer trucks, school busses, fire trucks, and other large vehicles can easily pass through the roundabouts. The manager of the school bus company that serves the Howard-SuamicoSchool District even stated that he would recommend roundabouts in other school districts.

The following are taken from: www.co.brown.wi.us/Planning/forms/lineville_roundabout_study.pdf

WASHINGTON STATE ROUNDABOUT

WASHINGTON SAFETY RECORD

Excerpts from Draft HDM Chapter 5

Roundabout WorkshopModule 3: Capacity Software

Roundabout Capacity Software

aaSIDRA RODEL / ARCADY SYNCHRO 6 Results of NCHRP 3-65 VISSIM PARAMICS

Two Types of Capacity Prediction Models

Empirical

RODEL or ARCADY Based on field

measurements, not theory

Capacity measured during at capacityoperation in U.K.

Gap Theory

SIDRA, SYNCHRO, VISSIM, Paramics Theoretical Capacity Seeing is believing

Note: They can give very different results

SIDRA

Developed in Australia Gap theory analysis Geometric parameters partially considered Used by 90% of the country Does signals, most other intersections also Calculates emissions Cost - $850 +/-

SIDRA Concerns over high capacity predictions

with low circulating flows can be resolved use 1.2 Environment Factor:

RODEL / ARCADY Developed in Great Britain Empirical analysis Geometric parameters considered Used by 30% of the country Some states use along with SIDRA

D.O.S. based Metric Only Only models roundabouts Cost - $800 for 1st copy then $300 each

Why Roundabouts Re-emerged

Research on 35 geometric variations

Many roundabouts were rehabilitated and new sites were considered

Follow up study confirmed the capacity prediction equations were valid

TRL study test track (U.K.) - 1968

Empirical Model

Strongly relates capacity to detailed geometry

Accidents also directly related to geometry Great tool for the design engineer Helps find the optimum geometry

Capacity of an Approach

The capacity of each entry to a roundabout was found to be a function of entering flow, circulating flow, and six geometric parameters.

Symbol

QeQcEVLDfR

Roundabout Capacity Prediction

Parameter

Capacity = maximum entering flow, pcu/hr

Circulating flow, pcu/hr Entry width, m Approach width, m Length of flare, m Inscribed circle dia., m Entry angle, degrees Entry radius, m

Geometric Parameters

Effective Geometric ParametersV = Approach

Roadway Width

E = Entry Width

L = Effective Flare Length

D = Inscribed Circle Diameter

R = Entry Radius

Phi = Entry angle

RODEL = ROundabout DELay

Capacity is VERY sensitive to geometry Delay Is VERY sensitive to capacity Therefore, delays can be incredibly sensitive

to geometry

The secret lies in the Delay-V/C curve This is the CRUX of intersection design Paradoxically the larger the delays and

queues, the easier they are to reduce.

Delays and the V/C Ratio

RODELs Confidence Level input Allows for variation / error in V/C Ratio assumption

Confidence Level range

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SYNCHRO / SimTraffic 6 Uses HCM 2000 equations Dont think any states use HCM 2000 Geometric parameters not considered Recently released Compared to real sites? Will only analyze single lane roundabouts SIM Traffic will simulate 4 lane

Doesnt calculate L.O.S. based on delay Will do most other intersections

SYNCHRO clip Single Lane Roundabout

SYNCHRO clip Multi Lane Roundabout

SYNCHRO clip - Interchange

NCHRP 3-65 National Cooperative Highway Research Program Project is wrapping up FHWA would like U.S. program Will be gap theory based Formula will not allow the excessive capacity prediction that some of

the other gap theory models can provide

*See the 3-65 shows from TRB Conference*

Simulation Programs

Not typically used for roundabout design are being used to visually check predictions Great tools for Public Info Meetings Able to show network impacts Visually displays improved performance

provided by roundabouts VISSIM seems to be top choice Paramics is comparable but more expensive

Slingerlands Bypass Overview

Blessing Road Traffic Simulation

VISSIM Clip using Level 1 - $2000

VISSIM Clip *see the TRB show*

VISSIM Clip using Level 2 - $2000 more

VISSIM Clip colors based on speed

VISSIM Clip Rt 44 Smithfield, RI

Paramics Clip costs around $12,000

Paramics Clip