Planning and designing of the planning and designing of the turbo roundabouts
Planning and Designing for Pedestrian Safety … · Essential roundabout characteristics 8-3....
Transcript of Planning and Designing for Pedestrian Safety … · Essential roundabout characteristics 8-3....
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ROUNDABOUTS:HOW THEY WORK FOR PEDESTRIANS
Module 8
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Golden CO
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Roundabouts:Learning Objectives:
Designing for Pedestrian Safety – Roundabouts
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At the end of this module, you will be able to: Explain why roundabouts reduce crashes Describe the safety benefits for pedestrians and
motor vehicles of roundabouts Describe how roundabout safety depends on correct
design
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Slow speed entry = yield
Slow speed exit
Truck apron
Splitter island
Crosswalk 1 car length back
Lots of deflection = slow speeds throughout
Separated sidewalks direct peds to crosswalks
Essential roundabout characteristics8-3
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Roundabouts are a type (or subset) of circular intersections
Designing for Pedestrian Safety – Roundabouts
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Roundabouts
RotariesNeighborhoodtraffic circles
All circularintersections
Others
Bottom Line: Not all circular intersections are roundabouts!!
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A roundabout is not: 1. A rotary, with large size & high speeds
Augusta ME8-5
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Problems with Existing Rotary8-6 Kingston NY
No control of entryHigh speed
Large diameter (600 ft +)
High speed weaving here
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Rotary Reconstructed to Roundabout8-7 Kingston NY
Smaller diameter (Typically 120 – 250 feet)
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A roundabout is not:2. A Washington DC style circle, with traffic signal controls
Washington DC8-8
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A roundabout is not:3. A traffic-calming mini circle
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A roundabout is not:4. Paris
Paris FR8-10
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Before and After Example8-11 Asheville NC
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Before and After Example8-12 Asheville NC
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Advantages for Pedestrians
Reduced vehicle speeds Reduced number of conflict points Shorter crossing distances Splitter island provides a refuge – ped crosses one
direction of traffic at a time
Crosswalk is placedone car length back
8-13 Bird Rock, San Diego, CA
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Roundabout8 Conflict Points
Vehicle-Pedestrian Conflict Points8-14
Conventional Intersection16 Conflict Points
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Roundabout are Safer for All Users
Pedestrian crashes: CMF = 0.73 (CRF = 27%)All crashes: Conversion from Two-way stop control:
All crashes: CMF = 0.56 (CRF = 44%) Injury crashes: CMF = 0.18 (CRF = 82%)
Conversion from signal control: All crashes: CMF = 0.52 (CRF = 48%) Injury crashes: CMF = 0.22 (CRF = 78%)
8-15 Clearwater FL
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Observational Pedestrian Safety Findings8-16 Santa Barbara CA San Diego CA
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Observational Pedestrian Safety Findings8-17 Clearwater FL Bend OR
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Pedestrian Movements at Roundabouts8-18
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Narrow entry slows driversChico, CA8-19
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1. At entry lane
Well defined crossings & splitter islandsBend OR8-20
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2. At exit lane
Well defined crossings & splitter islandsBend OR8-21
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Slow speeds improve safety at schools There are 100-plus roundabouts at schools in the US
Clearwater FL
Roundabout near Schools
8-22
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Lighting at Roundabouts
Study Source: Hasson and Lutkevich
Center Mounted Lighting: Peds visible only as
silhouettes Signs not visible
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Lighting at Roundabouts
Study Source: Hasson and Lutkevich
Approach Mounted Lighting:
Peds illuminated Signs illuminated
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Multi-lane roundabouts have potential for “multiple threat” and higher speeds
Monona WI8-25
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Drivers may take a straighter, faster path on entry and exit, resulting in higher speeds – lane markings are recommended to minimize this
Vail CO8-26
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Golden CO
Circulating traffic masks the sound cues used to identify gaps and masks the sound of yielding vehicles
Problems are much worse at multi-lane roundabouts
Roundabout concerns for peds with vision impairments:
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Possible Mitigation Measures for Blind Pedestrians at Multi-Lane Roundabouts
Public Right-of-Way Accessibility Guidelines (PROWAG, proposed rule July 26, 2011) require signals at multi-lane roundabout approaches: Pedestrian Hybrid Beacon (HAWK) Regular Red-Yellow-Green Signal
Research – other solutions may work: Raised Crosswalk Rectangular Rapid Flash Beacon Ped signal may rest in dark (optional use by peds)
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Pedestrian Hybrid Beacon at Two-lane Roundabout
8-29 Golden CO
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Raised Crosswalk at Two-lane Roundabout
8-30 Golden CO
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Rectangular Rapid Flash Beacon at Multilane Roundabout
8-31 Olympia WA
FHWA study found some benefits to accessibility after RRFB installation at multilane roundabouts
Other impacts (volume, speeds, configuration) also impact yielding
https://safety.fhwa.dot.gov/intersection/innovative/roundabouts/docs/fhwasa15069.pdf
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Case Study: Great Neck Plaza, NY
Problem/Background Small, dense, suburban community
on Long Island High pedestrian activity & older
population Busy central business district High-use train station
Excessive vehicle speeds
Great Neck Plaza, NY
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Case Study: Great Neck Plaza, NY
Solution City received traffic calming grant from
state DOT Goal: calm traffic, enhance visibility of
pedestrians, & improve crosswalk safety 4-way STOP replaced by roundabout
Contrasting pavement color, curb extensions, fencing, and islands used to direct traffic
Other locations: illuminated pedestrian crossings and speed awareness devices installed
Cost: $365,000 for the roundabout, $275,000 for the other improvements
Great Neck Plaza, NY
Before
After
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Case Study: Great Neck Plaza, NY
Results Pedestrian collisions reduced near the
roundabout after installation Users indicate a safer pedestrian
environment
Vehicle flow improved Effect of pedestrian crossing signs &
speed warning devices not as good Officials and residents consider project
a success
Great Neck Plaza, NY
Speed awareness device installed at same time as
roundabout
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Roundabout: Learning Outcomes
You should now be able to: Explain why roundabouts reduce crashes Describe the safety benefits for pedestrians and
motor vehicles of roundabouts Describe how roundabout safety depends on correct
design
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Questions?8-36