12. Our recent history has been active… 1990 1995 2000 1905: Columbus Circle (NYC) 1990: First modern use in U.S. 1920s-1950s: Rotary era 2009-2010: Updated FHWA Rbt Guide, MUTCD, HCM 2005 2010 1990s: MD, FL, O&D Guides 2001-2007: Explosion of state guides and manuals 2000: FHWA Rbt Guide 2007: NCHRP Report 572
29. Urban Double- and Multi-Lane Roundabout Examples Towson, MD Avon, CO
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32. U.S. Experience NCHRP Report 572 Results (May 2006) 82 44 Two-way stop (36) No significant change No significant change All-way stop (10) 78 48 Signalized (9) 76 35 All sites (55) % Reduction in Injury Crashes % Reduction in All Crashes Group Characteristic before Conversion (sample size)
33. Maryland’s Roundabout Accident Experience (March 2007 Study) Accident data at 15 state highway intersections converted to single-lane roundabouts between April 1993 and December 2003 86% reduction 0.16 1.13 Mean injury accident rate (acc./MEV) 68% reduction 0.61 1.91 Mean total accident rate (acc./MEV) 83% reduction 7.3 43.5 Total annual injury accidents 65% reduction 24.8 71.7 Total annual accidents % Change After Before
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35. Lower speed is safer for pedestrians Chance of pedestrian death increases with vehicle speed Source: United Kingdom
40. Roundabouts versus Signals: MUTCD Signal Warrant Threshold 0 2 4 6 8 10 12 14 16 18 20 600 700 800 900 1000 1100 1200 1300 1400 1500 Total Major Street Volume (veh/h) Average Delay (s/veh) Signal (10% left turns) Signal (50% left turns) Roundabout (10% left turns) Roundabout (50% left turns) Exhibit 3-7, p. 63 Based on MUTCD Warrant 3 (2000 ed.)/Warrant 11 (1988 ed.)
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42. Example of Land Use: Clearwater, FL Photo: City of Clearwater, FL Commercial w/ angle parking Residential
65. Case Study – Campus Drive/Daggett Avenue N Opportunities to improve ped/bike facilities Minimal ROW needs Reduction to one travel lane Roundabout? Example ped/bike improvements
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67. Thank You! Photo courtesy of Harper Houf Peterson Righellis, Inc.
Editor's Notes
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x New Guidance on Roundabouts October 2, 2009 Kittelson & Associates, Inc.