MATC Fall Lecture Series: Eugene Russell


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MATC Fall 2012 Lecture Series

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MATC Fall Lecture Series: Eugene Russell

  1. 1. MATC Seminar , September 14, 2012Dr Eugene R (Gene) Russell PE, PHD Professor Emerius, Kansas State University
  2. 2. Today’s 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. 3. Objective To be honest; give you reason to love roundabouts !
  4. 4. Intersection Crashes
  5. 5. Intersection Crashes contd..
  6. 6. Intersection Crashes contd..
  7. 7. Intersection Crashes contd..
  8. 8. FATALITIES2010: 32,885 fatalities, rate=1.11 vs 2002: 43,005 fatalities, rate =1.51 per 100MVM
  9. 9. INJURIES2010 2,239,ooo injured vs 2002 2,926,ooo rate 102 vs 75 per 100MVM
  10. 10. Traffic Signal Stop Sign% vehicles, all 26.6% 6.9%crashes
  11. 11. RED LIGHT RUNNING Preliminary estimates for 2001 indicate 200,000 crashes, 150,000 injuries, and about 1,100 deaths were attributed to red light running. This is down to around 800 deaths in 2010 The use of RLR cameras very controversial
  12. 12. Red Light Running
  13. 13. RLR Crashes 
  14. 14. Red Light Running Crashvideos  ng+videoo&view=detail&mid=5E92E1DA7FD1B5AEFE1A 5E92E1DA7FD1B5AEFE1A&first=0&qpvt=red+light+runn ing+videoo
  15. 15. My Main Point Traffic Signals and Stop Signs are not as safe as public thinks
  16. 16. What is a Modern Roundabout Or, What is it Not ?
  17. 17. Old Traffic Circles
  18. 18. Lane flow example lane Flow Example  ml What about signing?
  19. 19. Traffic Circle vs. RoundaboutKingston Traffic Circle Under Construction to become a Roundabout
  20. 20. Traffic Circle vs. RoundaboutMalta Roundabout superimposed on Latham Traffic Circle Tangential Approach geometry vs. Deflected Approach geometry Clearly defined exit
  21. 21. Traffic Circle vs. RoundaboutJohnson City Traffic Circle becomes Roundabout R C
  22. 22. NOT aRoundabout
  23. 23. Quick Comparison: Circle, rotary Modern Roundabout 40- 50 mph 15 – 25 mph Speeds 65-80 km/h Speeds 25-40 km/h Diameter > 60 meters Diameter < 60 meters About 200 ft About 200 ft High speed merge can Safer, low-speed, be confusing and adequate deflection Clear yield at entry
  24. 24. IIHS Video
  25. 25. Classic diagram 8 4 8 4 16 0 32 8
  26. 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. 27. Signalized intersection vehiclepedestrian conflicts
  28. 28. Conflict Point Comparison
  29. 29. vehicle pedestrian conflicts atsingle Lane roundabout
  30. 30. Conflict points for T intersections
  31. 31. U.S Single-Lane Roundabout Crashes- InsuranceInstitute for Highway Safety (IIHS) Study Results (IIHS) study [Persaud,, 2001] Highly significant reductions of approximately  40% for Overall Crashes  76% for Injury Crashes  90% for Fatal and Incapacitating Injury Crashes (predicted)
  32. 32. Using IIHS Figures Roundabouts have:  Potential to save motorists:  Hundreds of thousands of injury crashes  Thousands of deaths
  33. 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. 34. Benefits of a Roundabout (Cont’d) Community Benefits  Aesthetics/ Landscaping  Walkability/Village Atmosphere  Neighborhood Traffic Calming (secondary benefit)  Catalyst for Smart Growth  Lower life cycle costs at many intersections
  35. 35. FHWA Roundabout Guide 2nd ,NCHRP 672, and1st ed , NCHRP 572 Exh. 5-9
  36. 36. Hutchinson, RoundaboutThe Hutchinson News “If you do build a roundabout it will be the ‘Mother of all Bad Intersections’. We could sell tickets to see it.” “They are easy to find; just look for a traffic jam and the ground piled up with broken glass and car parts.” CARS Organization
  37. 37. Hutchinson, KS, 23th and Severence
  38. 38. Maryland Roundabout Mean Crash Rate Crashes per million entering vehicles Before After Total 1.53/MEV 0.97/MEV Injury 0.48/MEV 0.11/MEV
  39. 39. Before and After Mean accidentRates- Maryland Roundabout
  40. 40. Safety problems correctable byroundabouts Right angle, head-on, left and through, and U turn conflicts. High crash severity – injury or fatal. Sight distance or visibility problems that reduce the effectiveness of stop sign control. Inadequate separation of movements on some approaches Red light running
  41. 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. 42. Caveats Safety and efficiency achieved by a well designed roundabout keys:  Deflection  Low-speed  Lane continuity
  43. 43. Pedestrian Safety Major studies have found no fatalities at US roundabouts 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 pedestrian safety
  44. 44. Australian Roundabout Information Melbourne, AU  1970- 3 Roundabouts  2002- About 3000 Source: Andrew O’Brien
  45. 45. Australian Roundabout Informationcontd.. Traffic signals 1996 - 2000  1460 Crashes involving pedestrians  41 Fatalities  611 Serious injuries Source: Andrew O’Brien
  46. 46. Australian Roundabout Informationcontd.. Roundabouts 1996 - 2000  1097 Crashes  57 Involved Pedestrians  0 Fatalities  32 Serious-requiring hospitalization Source: Andrew O’Brien
  47. 47. Sample Single-Lane Roundabout PedestrianFacilities
  48. 48. Increased vehicle storage (number of vehicles a function of distance of exit lane crosswalk from circulating lane. ) In VISSIM prelim results,20, 60 100 vehicle storage for proximal, zig zg and distal
  49. 49. Visually Impaired Access Board recommendations -Engineering judgment for now; at least not enforceable standards PROWAG ( Public Right of Way Accessibility Guidelines) Blind difficulties: finding/aligning crossing, judging traffic flow, 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. 50. ADA and the Access-Board Around 2000 declared roundabouts not accessible. Draft language would have required pedestrian signals on all legs of all roundabouts. Later drafts require pedestrian signals on all legs of two or more lane roundabouts. Have indicated all along that full, green, yellow, red signals not necessarily required A-B latest language OKs HAWK (pedestrian hybrid signal )– or equivalent control that will make roundabout crosswalks accessible to blind pedestrians. ???????
  51. 51. Pedestrian Hybrid Signal-many stillcall HAWK
  52. 52. Hawk being researched in Lawrence, KS - UTC project
  53. 53. KSU Studies Researchers at Kansas State University (KSU) have been studying the operational performance of modern roundabouts since 1997
  54. 54. Candlewood & Gary, Manhattan, KS
  55. 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. 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. 57. KSU Studies contd.. Helped to establish that even at relatively low traffic volumes, modern roundabouts could be beneficial as a traffic control device at an intersection
  58. 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) 34.4 10.4 -71% 95% Queue Length (Feet) 190 104 -53%Degree Of Saturation- Intersection (v/c) 0.463 0.223 -53% Proportion Stopped- Intersection (%) 58 29 -52% Max Prop. Stopped (%) 62 37 -42%Before: Signal/AWSC/TWSC, RA: Roundabout
  59. 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. 60. Kansas Average-Environmental ImpactMeasures Of Effectiveness Before R.A % Diff. Carbon Monoxide (CO) Kg/hr 10.79 7.26 -33% Carbon dioxide (CO2) Kg/hr 237.30 127.59 -46% Oxides of Nitrogen (NOx) Kg/hr 0.348 0.225 -35% Hydrocarbons (HC) Kg/hr 0.446 0.210 -53%Before: Signal/AWSC/TWSC, RA: Roundabout
  61. 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. 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. 63. Bicycle conflicts Conflicts experienced by bicyclists that roundabouts are dependent on how they choose to negotiate the roundabout. This is similar to conventional intersections. For experienced cyclist riding through the roundabout conflicts are similar to those at signalized intersections. For those using the bike ramps and using the crosswalk, complex or similar to those of a pedestrian. A bicycle – pedestrian conflict is also possible. USA experience with bicycles is very limited.
  64. 64. Bicycles Provisions contd..
  65. 65. Netherlands- Geometric design for aroundabout that gives cyclists right-of-way
  66. 66. Netherlands- Geometric design for a roundaboutthat does not give cyclists right-of-way
  67. 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”- roundabout myths, I call “irrational opposition” Don’t like change Don’t like speed control (small circles)
  68. 68. Public Acceptance Improves WithExperienceSurvey by IIHSFeeling about Roundabouts BeforeAfterStrongly/Somewhat Favor 31% 63%Strongly/Somewhat Oppose 55% 28%
  69. 69. Conclusion At most intersections with significant cross traffic and turning movements the modern roundabout is the safest most efficient form of intersection control available today. After construction attitudes change to more positive Public needs more education
  70. 70. DEFLECTION ?
  71. 71. Flannery (2000) Study of Roundabout CrashesMain Causes:1. Approach geometry allowing high speed, and2. Lack of adequate deflection in the roundabout
  72. 72. New Zealand Safety Audit Study(Most common problems) One of the most common:  Inadequate deflection as motorists approach the intersection
  73. 73. HistoryCircular Intersections Circular places at the convergence of Roads since Middle Ages Examples Paris, Arc de Triomphe (history continued)
  74. 74.  Gyratory Operation- around1900  Eugéne Hènard, “Giratoire-boulevard” Place Ch. d’Gaulle (1907)  Wm. Phelps Eno, Columbus Circle (1904)  S.J. Hellier, Great Britain (1901) suggested a gyratory road system (history continued)
  75. 75.  London, Gyratory Systems introduced, 1925-26 One way systems around existing squares “circus” idea (Brown) “gyratories,” “rotaries,” “traffic circles” (history continued)
  76. 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 turn right from the left lane or change lanes in the intersection or anywhere without looking, signaling and finding a gap, BUT MANY DO IT IN ROUNDABOUTS ! WHY ?? I believe drivers losing respect for YIELD everywhere
  77. 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. 78. Give Way Rule (Yield at entry), 1966 Ended locking Improved capacity Reduced crashes Total change in design philosophy (history continued)
  79. 79. US History Massive road building in 1930’s Gyratory intersections generally called “traffic circles” were no advantage  Lost favor  By 1950’s no longer considered viable  Several “bad” circles still exist (history continued)
  80. 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. 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. 82.  1984, Design Standards about like todays  Entry path curvature standards  Concept of newer, smaller roundabouts as a “normal” roundabout  Prefer modern roundabout  Could say 1984 was birth of the modern roundabout world wide (history continued)
  83. 83. US Modern Roundabout Growth First in early 90’s 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 highway intersections. (end history)
  84. 84. Conclusions Statistically significant reductions in delay, queueing, stopping and emissions At most intersections with cross traffic and turning movements – a modern roundabout is the most viable alternative for safe, efficient vehicular traffic, especially for reducing injury crashes and deaths ! In new areas, after construction public attitudes change to more positive Public needs more education
  85. 85. My BeliefRoundabouts are the safest most efficient form of intersection traffic control available today !
  86. 86. The End
  87. 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 >