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Using Roundabouts for Mobility & Safety
October 17, 2018
Presented by: Hillary Isebrands, PE, PhDFHWA Resource CenterNational Safety & Design Team
Topics for Discussion
» The Roundabout Facts» High Speed Roadways» Large Vehicles» Pedestrians» Hot Topics» Discussion
2 11/9/2018 This presentation is dedicated to our friend Norman Hogue. Norman you will be missed.
The Facts
1. Well designed roundabouts SAVE LIVES!
2. Speed control and speed consistency are critical to safety (15-25 mph)
3. Single lane roundabouts only have 8 veh-veh conflict points
4. Right sizing the roundabout to fit the context/users will avoid over design
5. Phasing design/construction can reduce the risk with traffic projections
4 11/9/2018 Aerial photo: Isebrands
Roundabout Facts
Roundabouts are a Proven Safety Countermeasure
5 11/9/2018 Add a footer
US Capacity Models
Source: FHWA, Office of Safety
6
High Speed Roads
8
High Speed Approaches on Rural Roadways
Source: Google Earth
High Speed Approaches on Divided Highways
Source: MTJ Engineering; GoogleEarth
Large Vehicles
Freight and Over Size-Over Weight Vehicles
11 11/9/2018 Image Sources: Google Earth (upper left); Isebrands (lower left); Isebrands (middle)
Over Sized Overweight (OSOW)
Sources: Mark Lenters, GHD (left); Kansas DOT; Iowa DOT
Interchanges
13 11/9/2018 Image Sources: Colorado DOT (left); Google Earth (upper right); WashDOT (lower right)
14
Super Innovative Interchanges
Image Sources: Google Earth
Pedestrians
Alameda Ave/E Paisano Dr, El Paso, TX
Image Sources: Google Earth
• https://youtu.be/FW98z5LtylU
17
I-35 and 51st Street, Urban Interchange
Accessibility
18 11/9/2018 Hamilton Rd, Gahanna, Franklin County, OH
HOT Topics
» Public Education Campaigns» Phased approach to design – 10 year» Intersection Control Evaluation» Compact roundabouts» Turbo roundabouts» Temporary roundabouts» Innovative Construction Methods» Metering
Trending
20 11/9/2018 Sources: CDOT; Arcadis
21 11/9/2018 Add a footer
Education
22 11/9/2018 Add a footer
http://fortworthtexas.gov/roundabouts/howto/ https://hilliardohio.gov/roundabouts/
» NCHRP 03-130 Roundabouts: An Informational Guide, 3rd Edition (Underway)
» NCHRP 17-70: Development of Roundabout Crash Prediction Models and Methods (Anticipated 2018)
» FHWA - Mini Roundabout Safety and Operational Study (Anticipated 2018)
» NCHRP 834: Guidelines for the Application of Crossing Solutions at Roundabouts and Channelized Turn Lanes to Assist Pedestrians with Vision Disabilities (2017)
» Web Only – Document 222
» NCHRP 488 Synthesis: Roundabout Practices (2016)
Major Research Reports Since 2010
» FHWA Accelerating Roundabout Implementation – TOPR 34 (2015)
» NCHRP 03-110: Life Cycle Cost Analysis of Intersections (2015)
» NCHRP 772 - Evaluating the Performance of Corridors with Roundabouts (2014)
» Kansas DOT Accommodating Oversize/Overweight Vehicles at Roundabouts (2013)
» NCHRP 674 - Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities (2011)
» NCHRP 672 - Roundabouts: An Informational Report, Second Edition (2010)
Major Research Reports Since 2010
25
Bike roundabout rodeo
Source: Jeff Patten, FHWA
Intersection Control Evaluation (ICE) policy Development
26 11/9/2018 Add a footer
ICE is a data driven, performance-based framework and approach established to identify the optimal investment and solution for highway access issues and needs considering all users.
Wilmington, NC Temporary Roundabouts
27 11/9/2018 Image Source: City of Wilmington, NC
Proximity to Signals (as Meters)
28 Source: Omni GHD
Final Thoughts
» Roundabouts are still fairly “new”» Roundabout design not in all academic curriculum typically» Not every agency has a roundabout expert on board (and
that is okay)» You can learn a lot from a peer review – it makes you a better
designer/reviewer» A review during the process can reduce risks and time» They can result is a better project.
Peer Reviews Make Us Better
Source of Images: Google Earth30 11/9/2018
Get out of your Comfort Zone» Know the Facts» Get Outside » Draw Things» Have Hard Discussions
31 11/9/2018 Image Sources: Isebrands
32 11/9/2018
