Progress withroundabouts
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Progress withroundabouts Progress withroundabouts Document Transcript

  • Ourston Roundabout Engineering Progress with Roundabouts to Date Mark Lenters, President, Ourston Roundabout Engineering Inc. mlenters@ourston.com www.ourston.com 1 Progress by State Ourston Roundabout Engineering www.ourston.com 2 1
  • 1990: The First U.S. Modern Roundabouts Town Center Drive, Summerlin, Nevada Ourston Roundabout Engineering www.ourston.com 3 U.S. Since 1990 • 1990: Modern roundabouts built in Las Vegas. • 1995: UK style roundabouts replace signals & create “Roundabout Valley” in Avon/Vail, CO. • 1997: HCM adds roundabouts • 2000 and 2010: FHWA Roundabouts: An Informational Guide • 2010 HCM soon to be released • US Currently building ~ 350 per year, and rising. Ourston Roundabout Engineering www.ourston.com 4 2
  • National Collision Statistics • Original 24 roundabouts before and after (c. (c 2000) • Reduction in injuries = 76% • Combined reduction of all crashes = 40% • Follow-up study combining results of 55 sites 1998 - 2003: • 70% reduction in injuries • 35% reduction in all collisions combined • Similar to international statistics Ourston Roundabout Engineering www.ourston.com 5 National collision statistics for multi-lane roundabouts Reduction in All Types Intersection Type Before of Collisions with Roundabouts Traffic Signals 67% All-Way Stop Control 12% Two-Way Stop Control 19% Suburban Two-Way Stop Control 18% Urban Note: Results based on a study of 26 multi-lane intersections converted to multi-lane roundabouts with 3 years of before and after data (source: NCHRP Report 572, 2006) Ourston Roundabout Engineering www.ourston.com 6 3
  • Roundabout collisions = low severity (incorrect lane choice) Ourston Roundabout Engineering www.ourston.com 7 Roundabout collisions = low severity (failure to yield) Ourston Roundabout Engineering www.ourston.com 8 4
  • Teaching drivers ..at the at roundabout entry during opening Ourston Roundabout Engineering www.ourston.com 9 Ourston Roundabout Engineering Roundabout Site Selection Mark Lenters, President, Ourston Roundabout Engineering Inc. mlenters@ourston.com www.ourston.com 10 5
  • Identifying Candidate Intersections Local and State Initiatives: • Safet Improvements Safety Impro ements • Congestion relief • Development permit The Key mindset: - Be sure to solve a problem if a roundabout is to be used! Ourston Roundabout Engineering www.ourston.com 11 Selection process includes: 1. Initial planning level assessment performed as pa o a s udy to e a ua e the o e a part of study o evaluate e overall appropriateness of a roundabout; 2. Roundabout study considers site-specific conditions: • A safety assessment • Operational performance • Cost comparison 3. Requirements for drainage, lighting and public outreach. Ourston Roundabout Engineering www.ourston.com 12 6
  • Locations where roundabouts are suitable: 1. Safety – Intersections with historically high crash rates. – Roads with a historical problem of excessive speeds speeds. – Intersections with more than four legs or with difficult skew angles 2. Operations – A high % of turning movements and intersections that must accommodate U-turns. – High traffic volumes at peak hours – Intersections where widening one or more approach may be difficult or cost-prohibitive. – Ramp terminal intersections Ourston Roundabout Engineering www.ourston.com 13 Locations where roundabouts are suitable: Cont’d… • Intersections with high traffic growth (A single-lane roundabout staged f expansion t two lanes) d b t t d for i to t l ) • Transitions between rural and urban - gateways 3. Traffic Control • Existing two-way stop-controlled intersections that do not meet signal warrants. • Intersections or corridors where traffic calming is a desired outcome of the project. 4. Aesthetics • Focal point for a community, gateway or themed development Ourston Roundabout Engineering www.ourston.com 14 7
  • Initial Screening ADT Thresholds Ourston Roundabout Engineering www.ourston.com 15 Typical Roundabout Capacity Ranges Typical Daily Service Typical Inscribed Circle Roundabout Type Volume2 (vpd) Diameter1. 4-leg roundabouts Mini-Roundabout 45-80 ft (14-28 m) Less than 30,000 Urban Single-Lane 100 -150 ft (30 – 50 m) less than 25,000 Urban Multilane 160 - 215 ft (50 – 65 m) 25,000 to 55,000 (2-lane entry) Urban Multilane (3 or 4-lane 215 - 275 ft (65 – 85 m) 55,000 to 80,000 entry) Rural Single-Lane 130 -150 ft (35 – 55 m) less than 25,000 Rural M ltil R l Multilane 165 - 215 ft (50 – 65 m) 25,000 to 55,000 (2-lane entry) Rural Multilane 215 – 300 ft (65 – 85 m) 55,000 to 70,000 (3-lane entry) 1 Diameters are for general guidance. 2Capacities vary depending on entering volume and turning / circulating flow. Ourston Roundabout Engineering www.ourston.com 16 8
  • Conditions that may eliminate roundabout: 1. Coordinated signal system (platooned traffic) 2. R/W impacts 3. Inadequate SSD 4. Steep grades 5. Minor improvement is that are more cost- e ect e effective: • No R/W required • Extend left turn bay • Add turn bay in existing median Ourston Roundabout Engineering www.ourston.com 17 Conditions that may eliminate roundabout: 6. Intersections in close proximity to a signalized intersection (e.g., coordinated arterial signal systems) 7. Locations with steep grades and unfavorable topography that may limit visibility or an acceptable layout for a roundabout. 8. Intersections in close proximity to an at-grade railroad crossing. 9. Intersections where an unacceptable delay to the major p y j road could be created (90% main street traffic). 10. Heavy pedestrian or bicycle movements that may require signals. Ourston Roundabout Engineering www.ourston.com 18 9
  • Intersection Control Study 1. Project Background: describe site conditions 2. Safety Assessment (historical crash data) y ( ) 3. Alternate Sketches – lane configuration, rough alignment 4. Operational Analyses – Arcady, HCM 5. Cost Comparison – Construction, crash savings, life- cycle 6. Alternative Selection – screening criteria (capacity, safety, safety cost) 7. Conceptual Roundabout Design – nearly a 30% design 8. Conclusions and Recommendations Ourston Roundabout Engineering www.ourston.com 19 Ourston Roundabout Engineering Challenging but successful examples: - Railways - Corridors - Schools - Interchanges - Unusual geometry - Pedestrians - Closely space intersections - Rural intersections - Access management www.ourston.com 20 10
  • Daingerfield, TX Ourston Roundabout Engineering www.ourston.com 21 Daingerfield, TX Ourston Roundabout Engineering www.ourston.com 22 11
  • Corridor – Golden, CO • 4 Signals changed to RBTS • 60% ddrop i C h R t in Crash Rate • 94% drop in injuries – From 31 in 3 yrs to only one: a median opening left turn crash • No Pedestrian crashes • Single lane RBT has fewest 23 Space and cost savings in a corridor... Avon Colorado - Arterial Corridor, 1997 Ourston Roundabout Engineering www.ourston.com 24 12
  • Replaced traffic signals at main intersection Ourston Roundabout Engineering www.ourston.com 25 Two decades of planned expansion Second interchange for Wal-Mart in 2003 Ourston Roundabout Engineering www.ourston.com 26 13
  • Two interchanges in Vail, 1995 Interchange intersections previously controlled by police. Ourston Roundabout Engineering www.ourston.com 27 Unusual Geometry Avoided impacts to buildings & parking lots Ourston Roundabout Engineering www.ourston.com 28 14
  • Pedestrian Signals At Roundabouts Ourston Roundabout Engineering 29 www.ourston.com www.ourston.co Closely Spaced Intersections Lee Rd @ Whitmore Lake Rd and US-23, Metro Detroit Ourston Roundabout Engineering www.ourston.com 30 15
  • Rural High Speed Hwy. 85/Hwy. 17, 2006 Ourston Roundabout Engineering www.ourston.com 31 Access Management Loveland, CO Narrow Median possible because roundabouts b d b t allow U-turns Ourston Roundabout Engineering www.ourston.com 32 16
  • Rocky Mountain Avenue - 2008 Business is still thriving Ourston Roundabout Engineering www.ourston.com 33 Closely Spaced Intersections Lee Rd @ Whitmore Lake Rd and US-23, Metro Detroit Ourston Roundabout Engineering www.ourston.com 34 17
  • Contiguous Roundabouts Ourston Roundabout Engineering www.ourston.com 35 Access Management • Minor driveways can be designated as in intersection leg for access near entries or exits Ourston Roundabout Engineering www.ourston.com 36 18
  • Transition Between Urban Forms (Clearwater Beach, FL) Commercial with angle parking Photo: City of Clearwater FL r, Residential Ourston Roundabout Engineering www.ourston.com 37 J.F.K. Middle School, Clearwater, FL (>50 others like it in the U.S. being tracked) Ourston Roundabout Engineering www.ourston.com 38 19
  • Non-Conforming Circle Becomes a Roundabout (Long Beach, CA, 1992) Ourston Roundabout Engineering www.ourston.com 39 Ourston Roundabout Engineering Achieving Success Using Roundabouts Mark Lenters, President, Ourston Roundabout Engineering Inc. mlenters@ourston.com www.ourston.com 40 20
  • The Recipe for Successful Use of Roundabouts • Lead with an Area-Wide Policy: – Roundabouts shall be considered when… – Conduct Alternatives Analyses (life cycle) – Top-down consensus building – Only use roundabouts to solve a problem 1.Assemble general policy tools 2.Develop project specific tools Ourston Roundabout Engineering www.ourston.com 41 General and Specific Outreach Tools General Tools Project Specific Tools • Case studies • Scale model • Testimonials • Animation/simulation • National statistics • Renderings • How-to videos • Project web page • Web-cam • Project brochure • Driver training • Website • Brochures Ourston Roundabout Engineering www.ourston.com 42 21
  • Scale Model (1:87 = ‘HO’ scale) Ourston Roundabout Engineering www.ourston.com 43 Coordination of Geometry and Lane Designation 44 22
  • SB Pioneer Road Movement Ourston Roundabout Engineering 45 www.ourston.com NB Belt Line Road Movement Ourston Roundabout Engineering 46 www.ourston.com 23
  • Area-wide Education Campaigns • Making Pedestrians more active… Ourston Roundabout Engineering www.ourston.com 47 24