1.MATC Seminar , September 14, 2012Dr Eugene R (Gene) Russell PE, PHDProfessor Emerius,Kansas State University

2. Todays Presentation Why Roundabouts ? Intersection safety statistics Circle Differences Safety examples Latest roundabout crash statistics Pedestrian/ Bicycle safety Visually impaired concerns & PROWAG Benefits other than safety Some history- IF TIME PERMITS 3. Objective To be honest; give you reason to love roundabouts ! 4. Intersection Crasheshttp://www.nhtsa.gov/nhtsa/announce/speeches/030503Peters/FHWA-AASHTO030602.pdf 5. Intersection Crashes contd..http://www.nhtsa.gov/nhtsa/announce/speeches/030503Peters/FHWA-AASHTO030602.pdf 6. Intersection Crashes contd..http://www-nrd.nhtsa.dot.gov/pdf/nrd-30/NCSA/Rpts/2003/2002EARelease.pdf 7. Intersection Crashes contd..http://www-nrd.nhtsa.dot.gov/pdf/nrd-30/NCSA/Rpts/2003/2002EARelease.pdf 8. FATALITIES2010: 32,885 fatalities, rate=1.11 vs 2002: 43,005 fatalities, rate =1.51 per 100MVM 9. INJURIES2010 2,239,ooo injured vs 2002 2,926,ooo rate 102 vs 75 per 100MVM 10. Traffic Signal Stop Sign% vehicles, all26.6%6.9%crashes 11. RED LIGHT RUNNING Preliminary estimates for 2001 indicate 200,000crashes, 150,000 injuries, and about 1,100 deaths wereattributed to red light running. This is down to around 800 deaths in 2010 The use of RLR cameras very controversial 12. Red Light Running 13. RLR Crashes http://www.youtube.com/watch?v=NC-rimCfu50 14. Red Light Running Crashvideos http://www.bing.com/videos/search?q=red+light+runni ng+videoo&view=detail&mid=5E92E1DA7FD1B5AEFE1A 5E92E1DA7FD1B5AEFE1A&first=0&qpvt=red+light+runn ing+videoo 15. My Main Point Traffic Signals and Stop Signs are not as safe as public thinks 16. What is a Modern Roundabout Or, What is it Not ? 17. Old Traffic Circles 18. Lane flow example lane Flow Example http://www.ourston.com/resources/webcams/halifax.ht ml What about signing? 19. Traffic Circle vs. RoundaboutKingston Traffic Circle Under Construction to become a Roundabout 20. Traffic Circle vs. RoundaboutMalta Roundabout superimposed on Latham Traffic Circle Tangential Approach geometry vs. Deflected Approach geometryClearly defined exit 21. Traffic Circle vs. RoundaboutJohnson City Traffic Circle becomes RoundaboutR C 22. NOT aRoundabout 23. Quick Comparison:Circle, rotary Modern Roundabout40- 50 mph 15 25 mphSpeeds 65-80 km/hSpeeds 25-40 km/hDiameter > 60 meters Diameter < 60 metersAbout 200 ft About 200 ftHigh speed merge can Safer, low-speed,be confusing and adequate deflection Clear yield at entry 24. IIHS Video 25. Classic diagram8 4 84 16 0 32 8 26. Pedestrian conflictsConventional intersections; potential vehicularconflicts, each coming from a different direction:1. Left turn, through and right turn movements from the leg of the intersection the pedestrian is crossing.2. Through movements coming from the opposite side of the intersection.3. Right turns from the cross street.4. Left turns from the cross Street.5. Right turn on red 27. Signalized intersection vehiclepedestrian conflicts 28. Conflict Point Comparison 29. vehicle pedestrian conflicts atsingle Lane roundabout 30. Conflict points for T intersections 31. U.S Single-Lane Roundabout Crashes- InsuranceInstitute for Highway Safety (IIHS) Study Results (IIHS) study [Persaud, et.al., 2001] Highly significant reductions of approximately 40% for Overall Crashes 76% for Injury Crashes 90% for Fatal and Incapacitating Injury Crashes (predicted) 32. Using IIHS Figures Roundabouts have: Potential to save motorists: Hundreds of thousands of injury crashes Thousands of deaths 33. Benefits of a Roundabout SAFETY, particularly injury crashes and fatalities Including safer left turns (all right turns) More efficient traffic flow Increased capacity for given level of demand Less vehicle air pollution Pedestrian safety Access management 34. Benefits of a Roundabout (Contd) Community Benefits Aesthetics/ Landscaping Walkability/Village Atmosphere Neighborhood Traffic Calming (secondary benefit) Catalyst for Smart Growth Lower life cycle costs at many intersections 35. FHWA Roundabout Guide 2nd ,NCHRP 672, and1st ed , NCHRP 572Exh. 5-9 36. Hutchinson, RoundaboutThe Hutchinson News If you do build a roundabout it will be the Mother ofall Bad Intersections. We could sell tickets to see it. They are easy to find; just look for a traffic jam andthe ground piled up with broken glass and car parts. CARS Organization 37. Hutchinson, KS, 23th and Severence 38. Maryland Roundabout Mean Crash RateCrashes per million entering vehiclesBeforeAfter Total 1.53/MEV0.97/MEVInjury 0.48/MEV0.11/MEV 39. Before and After Mean accidentRates- Maryland Roundabout 40. Safety problems correctable byroundabouts Right angle, head-on, left and through, and U turnconflicts. High crash severity injury or fatal. Sight distance or visibility problems that reduce theeffectiveness of stop sign control. Inadequate separation of movements on someapproaches Red light running 41. Statement from Discover MagazineAround 2000 :The modern roundabout may be the safest most efficient traffic control device available today.I say it is ! 42. Caveats Safety and efficiency achieved by a well designed roundabout keys: Deflection Low-speed Lane continuity 43. Pedestrian Safety Major studies have found no fatalities at USroundabouts Cross one lane at a time- single lane Cross traffic going in one direction at a time. Less likely to be killed at low speeds Actually very little US data on pedestrian safety Worldwide, roundabouts show increase in pedestriansafety 44. Australian Roundabout Information Melbourne, AU 1970- 3 Roundabouts 2002- About 3000Source: Andrew OBrien 45. Australian Roundabout Informationcontd.. Traffic signals 1996 - 2000 1460 Crashes involving pedestrians 41 Fatalities 611 Serious injuriesSource: Andrew OBrien 46. Australian Roundabout Informationcontd.. Roundabouts 1996 - 2000 1097 Crashes 57 Involved Pedestrians 0 Fatalities 32 Serious-requiring hospitalizationSource: Andrew OBrien 47. Sample Single-Lane Roundabout PedestrianFacilities 48. Increased vehicle storage (number of vehicles a functionof distance of exit lane crosswalkfrom circulating lane. ) In VISSIM prelim results,20, 60 100 vehicle storage for proximal, zig zg and distal 49. Visually Impaired Access Board recommendations -Engineering judgment fornow; at least not enforceable standards PROWAG ( Public Right of Way Accessibility Guidelines) Blind difficulties: finding/aligning crossing, judging trafficflow, evaluating gaps. Issues at roundabouts Wayfinding to set back crossing Traffic flow sounds not clear Gap Creation without stop condition Gap Detection not as clear as at stop control 50. ADA and the Access-Board Around 2000 declared roundabouts not accessible. Draft language would have required pedestrian signalson all legs of all roundabouts. Later drafts require pedestrian signals on all legs oftwo or more lane roundabouts. Have indicated all along that full, green, yellow, redsignals not necessarily required A-B latest language OKs HAWK (pedestrian hybridsignal ) or equivalent control that will makeroundabout crosswalks accessible to blindpedestrians. ??????? 51. Pedestrian Hybrid Signal-many stillcall HAWK 52. Hawk being researched in Lawrence, KS - UTC project 53. KSU Studies Researchers at Kansas State University (KSU) have been studying the operational performance of modern roundabouts since 1997 54. Candlewood & Gary, Manhattan, KS 55. KSU Roundabout Performance The primary focus of this research was to study the operational performance of 11 Kansas roundabout s The research focused on eleven sites with different traffic volume ranges where a modern roundabout has replaced or built instead of a Stop or Signal controlled intersection 56. KSU Studies contd.. Results of studies for Kansas DOT at several roundabouts indicate that the operational performance of roundabouts is better than TWSC, AWSC and Signalized intersections at all locations studied 57. KSU Studies contd.. Helped to establish that even at relatively low trafficvolumes, modern roundabouts could be beneficial as atraffic control device at an intersection 58. Kansas Average-Operational Performance Measures Of Effectiveness Before R.A % Diff.Average Intersection Delay (Seconds/Veh)20.2 8 -65% Max Approach Delay (Seconds/Veh) 34.410.4 -71% 95% Queue Length (Feet)190 104-53%Degree Of Saturation- Intersection (v/c)0.463 0.223-53% Proportion Stopped- Intersection (%)5829-52%Max Prop. Stopped (%)6237-42%Before: Signal/AWSC/TWSC, RA: Roundabout 59. Emissions Major pollutants Carbon monoxide (CO), Carbon dioxide (CO2), Oxides of nitrogen (NOx), Particulate matter (PM10 ,PM2.5) Hydrocarbons (HC) or Volatile Organic Compounds(VOC) Modern Roundabouts cut emissions 60. Kansas Average-Environmental ImpactMeasures Of EffectivenessBeforeR.A % Diff. Carbon Monoxide (CO) Kg/hr 10.797.26 -33% Carbon dioxide (CO2) Kg/hr237.30 127.59-46%Oxides of Nitrogen (NOx) Kg/hr0.3480.225-35%Hydrocarbons (HC) Kg/hr 0.4460.210-53%Before: Signal/AWSC/TWSC, RA: Roundabout 61. KSU/IIHS Study- Delay & Proportion StoppedKansas, Maryland & Nevada TWSC (Before) vs. Roundabout (After) About 20% reduction in total delay 13% to 23% reduction in delay per vehicle 14% to 43% reduction in proportion stopped 62. ENERGY- Gasolene Usage Another IIHS study of 10 signalized intersections: If converted to roundabouts: Each vehicle delay would be 1 minute less Annual delay savings 325,000 hours Fuel savings, 235,000 gallons/year 63. Bicycle conflicts Conflicts experienced by bicyclists that roundaboutsare dependent on how they choose to negotiate theroundabout. This is similar to conventionalintersections. For experienced cyclist riding through the roundaboutconflicts are similar to those at signalizedintersections. For those using the bike ramps and using thecrosswalk, complex or similar to those of a pedestrian. A bicycle pedestrian conflict is also possible. USA experience with bicycles is very limited. 64. Bicycles Provisions contd.. 65. Netherlands- Geometric design for aroundabout that gives cyclists right-of-way 66. Netherlands- Geometric design for a roundaboutthat does not give cyclists right-of-way 67. Public Acceptance Generally poor- initially Confusion with Old circles, rotaries Sometimes small circles Heard or experienced lots of bad things about large,old circles Lots of misinformation out there- roundaboutmyths, I call irrational opposition Dont like change Dont like speed control (small circles) 68. Public Acceptance Improves WithExperienceSurvey by IIHSFeeling about RoundaboutsBeforeAfterStrongly/Somewhat Favor31% 63%Strongly/Somewhat Oppose 55% 28% 69. Conclusion At most intersections with significant cross traffic andturning movements the modern roundabout is thesafest most efficient form of intersection controlavailable today. After construction attitudes change to more positive Public needs more education 70. DEFLECTION ? 71. Flannery (2000) Study of Roundabout CrashesMain Causes:1. Approach geometry allowing high speed, and2. Lack of adequate deflection in the roundabout 72. New Zealand Safety Audit Study(Most common problems) One of the most common: Inadequate deflection as motorists approach the intersection 73. HistoryCircular Intersections Circular places at the convergence of Roads sinceMiddle Ages ExamplesParis, Arc de Triomphe (history continued) 74. Gyratory Operation- around1900 Eugne Hnard, Giratoire-boulevard Place Ch.dGaulle (1907) Wm. Phelps Eno, Columbus Circle (1904) S.J. Hellier, Great Britain (1901) suggested a gyratoryroad system (history continued) 75. London, Gyratory Systems introduced, 1925-26 One way systems around existing squares circus idea (Brown) gyratories, rotaries, traffic circles(history continued) 76. Driver education SLOW DOWN Watch for pedestrians Single lane- should be no problem Multilane- get in right lane on entry ! Design should provide lane continuity. At traditional intersection, Most drivers would not turnright from the left lane or change lanes in the intersectionor anywhere without looking, signaling and finding agap, BUT MANY DO IT IN ROUNDABOUTS ! WHY ?? I believe drivers losing respect for YIELD everywhere 77. Great Britain roundabout development to 1966 Worked poorly-large queues, locking Bigger and bigger designs weaving Did not end jams Compromised safety Intolerable by 1966 Almost gave up on them (history continued) 78. Give Way Rule (Yield at entry), 1966 Ended locking Improved capacity Reduced crashes Total change in design philosophy(history continued) 79. US History Massive road building in 1930s Gyratory intersections generally called trafficcircles were no advantage Lost favor By 1950s no longer considered viable Several bad circles still exist(history continued) 80. Early US Designs Large Priority at entry High speed entry Weaving in circle/confusing High crash rates Important re-current acceptance(history continued) 81. Great Britain, Post 1966 1975, revised design guidelines Introduced concept of deflection Islands at entry (splitter islands, generally raised ) and central island (history continued) 82. 1984, Design Standards about like todays Entry path curvature standards Concept of newer, smaller roundabouts as anormal roundabout Prefer modern roundabout Could say 1984 was birth of the modernroundabout world wide(history continued) 83. US Modern Roundabout Growth First in early 90s 90 in 1995 About 3000-4000 today In Kansas: ONE in 1997; about 175 today in operation,being built or planned.; 6 on major state highwayintersections.(end history) 84. Conclusions Statistically significant reductions indelay, queueing, stopping and emissions At most intersections with cross traffic and turningmovements a modern roundabout is the most viablealternative for safe, efficient vehiculartraffic, especially for reducing injury crashes anddeaths ! In new areas, after construction public attitudeschange to more positive Public needs more education 85. My BeliefRoundabouts are the safest most efficient form of intersection traffic control available today ! 86. The End 87. Eugene R(Gene)Russell Sr.,PE, PhD,Professor Emeritus of Civil Engineering,Department of Civil Engineering,2118 Fiedler HallKansas State University, Manhattan, KS 66506Ph . 785 539 9422; Fx 785 532 7717;Cell. 785 410 5231email. < geno @ ksu . edu >