Modern Roundabouts: Safety & Mobility Wrapped in a Pretty Package
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http://www.ohm-advisors.com - Mad about Modern Roundabouts: Coupling Safety and Mobility. This presentation delivers a primer on roundabouts, the differences between roundabouts, traffic circles and rotaries, and the important rules of roundabouts.
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Modern Roundabouts: Safety & Mobility Wrapped in a Pretty Package
- 1. Jim Marcinkowski, PE ASCE, APWA & SWE Redding, California May 17, 2010
- 29. TRAFFIC SIGNALS ARE NOT SAFETY DEVICES
- 33. All crashes All injury crashes Serious injury & fatal crashes
- 36. (17+ seconds curb to curb) (<4 seconds each crossing) Typical Intersection = 60’ vs. Roundabout = 13’ x 2
Editor's Notes
- Modern Roundabouts 09/23/10
- Modern Roundabouts 09/23/10 In their own way, rdbts may be intimidating to drivers. Single-lane rdbts are not really that hard to master, and drivers can acclimate to them rather quickly. However, the use of two or even 3-lane rdbts are not yet common and require a sophistication of design to get good results.
- Modern Roundabouts 09/23/10
- Modern Roundabouts 09/23/10
- Modern Roundabouts 09/23/10
- Modern Roundabouts 09/23/10 Here are the fundamentals for roundabouts. These apply for all rdbts, from a mini-rdbt in a subdivision handling maybe 100 vph in its peak, up thru a 3-lane rdbt, with by-pass lanes, serving upwards of 7,000 to 8,000 vph.
- Modern Roundabouts 09/23/10
- Modern Roundabouts 09/23/10 Again, you need to understand the score card for rdbts. Like other treatments there are good and bad points to consider. When done correctly … (summarize list) There have been a number of studies of US intersections converted from signals to Rdbts; they point to dramatic reductions in number & severity of crashes. Rdbts have far fewer conflict points. When used at interchanges, Rdbt = 6 merge + 6 diverge + 0 crossing = 12. Conventional ramps = 26 points, including 10 crossing.
- Modern Roundabouts 09/23/10 For purposes of general guidance, note that I am suggesting that placing rdbts near RR grade crossings is a negative. However, there are an number of locations (many in the U.K, only a handful yet in the U.S) where a rail line passes directly thru the heart of a rdbt. It CAN be made to work; but the attempt should be left in the hands of experts.
- Modern Roundabouts 09/23/10
- Modern Roundabouts 09/23/10
- Modern Roundabouts 09/23/10
- Modern Roundabouts 09/23/10
- Modern Roundabouts 09/23/10
- Modern Roundabouts 09/23/10
- Modern Roundabouts 09/23/10
- Modern Roundabouts 09/23/10