1 Modern Roundabouts – The Safer Intersection Choice Mark Doctor, PE FHWA Resource Center Safety & Design Technical Service Team Proven Safety Measures Workshop January 10, 2010 Photo: Mt. Horeb, WI

Modern Roundabouts – the safer intersection choice 2 Presentation Overview What is a modern roundabout? –(i.e., how is it different from other types of circular intersections?) Why are roundabouts safer? Where are roundabouts appropriate? Where can I get more information?

Modern Roundabouts – the safer intersection choice 3 Pedestrian Crossing Central IslandCounter-clockwise Circulatory Roadway Deflected Entry Path with Yield control Splitter Island What is a Modern Roundabout?

Modern Roundabouts – the safer intersection choice 4 Typically, modern roundabouts are – smaller than rotaries designed for slower entry, circulating, and exit speeds always follow a “yield-at-entry” traffic control principle designed with a raised splitter island to slow and deflect traffic prior to entry designed to facilitate safer pedestrian crossings designed to follow a same lane entry/lane exit principle at multilane roundabouts –(NO LANE CHANGES in the circulatory roadway) Modern roundabouts are different from the older “Rotary” style intersections!!!

Modern Roundabouts – the safer intersection choice 5 Older “Rotary” Circles are not Roundabouts !!! Cony Rotary Augusta, ME

Modern Roundabouts – the safer intersection choice 6 Signalized Traffic Circles are not Roundabouts !!! Dupont Circle, Washington, DC Is Not a Roundabout

Modern Roundabouts – the safer intersection choice 7 Modern roundabouts are different from traffic calming circles!!! Examples of traffic calming circles – NOT ROUNDABOUTS

Modern Roundabouts – the safer intersection choice 8 Roundabouts are a type or subset of circular intersections Roundabouts Rotaries Neighborhood traffic circles All circular intersections Others Key Message: Not all circular intersections are roundabouts!!!

Modern Roundabouts – the safer intersection choice 9 32 conflict points High-speed High-angle High-energy 8 conflict points Low-speed Low-angle Low-energy Slide Credit: Michael Wallwork, PE 75% fewer conflicts Why are roundabouts safer? The laws of physics!!! Comparison of Vehicle Conflict Points

Modern Roundabouts – the safer intersection choice 10 A Common Geometric Control at an Intersection: “Right-in / Right-out”

Modern Roundabouts – the safer intersection choice 11 Roundabouts Operate Very Similarly – All Movements are “Right In / Right Out”

Modern Roundabouts – the safer intersection choice 12 Roundabouts also reduce Vehicle - Pedestrian Conflicts 16 Conflicts 8 Conflicts

Modern Roundabouts – the safer intersection choice 13 That all sounds good in theory …. but what do the “numbers” show? The Insurance Institute for Highway Safety – U.S. Roundabout Safety Report Before-after studies at 24 intersections 39% overall decrease in crashes 76% decrease in injury crashes 89% decrease in fatal/incapacitating crashes 75% reduction in traffic delays! NCHRP Report 572 – Roundabouts in the US Before-after studies at 55 intersections 35% overall decrease in crashes 76% decrease in injury crashes 81% decrease in fatal/incapacitating crashes for single lane urban roundabouts 71% decrease in fatal/incapacitating crashes for single lane rural roundabouts Key Message: : Roundabouts are SAFER !!!

Modern Roundabouts – the safer intersection choice 14 Where are roundabouts appropriate? New intersections Replacement of all-way stops Replacement of two-way stops when side street delay becomes excessive Replacement of signalized intersections –Roundabouts can better accommodate highly unbalanced movements 3-leg intersections with heavy left-turn volumes

Modern Roundabouts – the safer intersection choice 15 Intersections with a high-crash rate or a higher severity of crashes Roundabouts may be particularly advantageous at: Roundabouts improve safety by simplifying traffic movements, reducing potential conflict points, and reducing vehicle speeds Where are roundabouts appropriate?

Modern Roundabouts – the safer intersection choice 16 Where are roundabouts appropriate? Intersections with complex geometry, skew angles, or more than four approaches Roundabouts may be particularly advantageous at: Before After Albuquerque, NM – Central Ave. and 8th

Modern Roundabouts – the safer intersection choice 17 Where are roundabouts appropriate? Rural intersections with high-speed approaches Roundabouts may be particularly advantageous at: Elongated splitter islands with successive reverse curvature can greatly improve safety at high speed approaches by alerting drivers to a changed traffic condition ahead.

Modern Roundabouts – the safer intersection choice 18 Where are roundabouts appropriate? Intersections with high U-turn movements Roundabouts may be particularly advantageous at: Roundabouts facilitate the use of raised medians for access management along the roadway by making U-turn movements easier at the intersections.

Modern Roundabouts – the safer intersection choice 19 Where are roundabouts appropriate? Transitions or “Gateways” from higher speed to lower speed areas Where aesthetics are important Roundabouts may be particularly advantageous at: Roundabouts make for good transitions in speed change (including rural to urban transitions).

Modern Roundabouts – the safer intersection choice 20 Where are roundabouts appropriate? Intersections near schools Roundabouts may be particularly advantageous at: Roundabouts control speeds High School Gaylord, MI

Modern Roundabouts – the safer intersection choice 21 Roundabouts Near Schools “It definitely has improved the flow of traffic and has not proved to be the safety concern that several parents feared.” - Jeri Mifflin, Principal, Bennett Woods Elementary School Okemos, MI

Modern Roundabouts – the safer intersection choice 22 So, why aren’t more agencies using roundabouts? “The public will lynch us if we propose a roundabout.” “I know how people drive in my town – they’ll never get used to a roundabout.” “We’ll get sued because of all the crashes it will cause.” Pick Your Favorite Excuse:

Modern Roundabouts – the safer intersection choice 23 Roundabouts are often confused with other types of circular intersections ≠ “we have had a lot of people not very happy about the idea of roundabouts, but after they are constructed, those fears mostly go away.” Brian Walsh - Washington State DOT

Modern Roundabouts – the safer intersection choice 24 Driver Opinion Survey on Roundabouts FAVOR OPPOSE Source: Insurance Institute for Highway Safety

Modern Roundabouts – the safer intersection choice 25 Sometimes it takes perseverance!!! Photo source: NYSDOT

Modern Roundabouts – the safer intersection choice 26 Where can I get more information? FHWA brochure – available FHWA Technical Summary on roundabout design – Soon FHWA Technical Summary on mini-roundabouts – Soon FHWA DVD aimed at decision makers – Spring 2010 One-day NHI Training Course on Roundabouts - mid 2010 Updated Roundabout Informational Guide from NCHRP – mid 2010 Ongoing research studies (NCHRP and others) on roundabout pedestrian safety and treatments for sight- impaired pedestrians

Modern Roundabouts – the safer intersection choice 27 For more information …. or contact: Mark Doctor, FHWA Resource Center (404)

Modern Roundabouts – the safer intersection choice 28 Questions ???