Pedestrians who are blind at Roundabouts Janet Barlow, COMS Accessible Design for the Blind FHWA...
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Transcript of Pedestrians who are blind at Roundabouts Janet Barlow, COMS Accessible Design for the Blind FHWA...
Pedestrians who are blind
at Roundabouts
Janet Barlow, COMSAccessible Design for the Blind
FHWA WebinarAugust 13, 2010
Accessible Design for the Blind, 8/13/2010, Slide
Transportation choices for individuals who are blind or who have low visionWalkPublic transit - Bus or railParatransit servicesTaxis or shuttlesRides from friends or relativesPaid drivers
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Accessible Design for the Blind, 8/13/2010, Slide
Pedestrians with low vision (many of our growing elderly population)
May have difficulty with depth perception
Problems in judging location of vehicles Problems in judging approach speed of vehicles
May have reduced contrast sensitivity
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Accessible Design for the Blind, 8/13/2010, Slide
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Travel in unfamiliar locations
Pedestrians who are blind or visually impaired in the US do travel to new locations or intersections and ‘figure them out’ by listening and exploring
Accessible Design for the Blind, 8/13/2010, Slide
Aids and techniques for obstacle and curb detection
Long white caneUsed as a probe of the walking surfaceMay identify person as visually impaired
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Aids and techniques for obstacle and curb detection
Dog guideGuides around obstaclesStops at curbs or drop-offs
Low vision aid, such as telescope
Used only for specific tasks, ie reading sign
Accessible Design for the Blind, 8/13/2010, Slide
Orientation and alignment cues
Slight slopes and changes in surface texturesSidewalk and/or grass line or building lineTraffic – both parallel to travel path and perpendicular to travel pathOther pedestrians, sun, other cuesAwareness of intersecting streets and general layout of area
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Accessible Design for the Blind, 8/13/2010, Slide
Crossing cues
Signalized Traffic stopping on the street that the pedestrian is planning to crossVehicles starting and moving across the intersection in the closest through lane
UnsignalizedHearing a vehicle approachingNot hearing any vehicles Hearing a vehicle yieldingTraffic moving parallel to crosswalk
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Accessible Design for the Blind, 8/13/2010, Slide
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Wayfinding issues
Recognizing that the intersection is a roundabout
Locating crosswalksAligning to cross
Accessible Design for the Blind, 8/13/2010, Slide
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Locating crosswalks
Where blind pedestrian might cross (if unaware that’s it’s a roundabout)
Accessible Design for the Blind, 8/13/2010, Slide
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Finding proper crossing location
CrosswalkHave to turn before intersection
Accessible Design for the Blind, 8/13/2010, Slide
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Finding proper crossing location
Or continue around the corner
Accessible Design for the Blind, 8/13/2010, Slide
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Wide curb ramp may be mistaken for driveway; also wider than crosswalk
Accessible Design for the Blind, 8/13/2010, Slide
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Landscaping could have been used to guide person to crosswalk and to help
them align to cross
Accessible Design for the Blind, 8/13/2010, Slide
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Potential treatments – wayfinding
Design of sidewalkTactile features or fencesSound cues from audible signals
Accessible Design for the Blind, 8/13/2010, Slide
Issues with determining when to cross
Detecting a gap in trafficDetecting that vehicle has yielded
For pedestrians who are blind, research has documented
latency and delay in detecting gap or yield, and subsequent inability to crossunsafe judgments about gaps or yields
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Accessible Design for the Blind, 8/13/2010, Slide
Detecting a gap, or yield
Using hearing alone, it is not always possible to pinpoint direction of sound
not as specific as visioncannot select just one lane or area to check
One vehicle can mask the sound of others approaching, possibly closerQuieter cars further complicate this problem
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Accessible Design for the Blind, 8/13/2010, Slide
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Latency and delay in detecting gaps
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1
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Entry lane Exit lane
Mea
n g
ap
det
ecti
on
la
ten
cy (
sec)
blind sighted
Accessible Design for the Blind, 8/13/2010, Slide
Sound masking
Vehicles that have just passed the crosswalkVehicles in the circulatory roadwayVehicles approaching in other lane of the street the pedestrian is crossing (behind of or in front the splitter island)Vehicles that stop to allow the pedestrian to cross (multi-lane roundabout) mask sound of vehicles approaching in other lane
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Accessible Design for the Blind, 8/13/2010, Slide
Sound masking
Vehicles on nearby bridges/expresswaysOther sounds in the environment
LawnmowersNearby constructionHigh ambient noise
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Accessible Design for the Blind, 8/13/2010, Slide
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Pedestrian who is blind cannot safely assume that drivers will yield
Accessible Design for the Blind, 8/13/2010, Slide
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Driver yielding behaviorNEI research – Maryland roundabout
Likelihood of yielding diminishes with increasing speed White cane has only modest impact on yielding behaviorAt one location, drivers yielded 79% of the time for the entry lanes, but only 37% of the time for the exit lanes
FHWA research – 11.5% of vehicles yieldedNCHRP 3-78 research – several locations - yielding rates varied
Single lane roundabouts - entry – rates ranged from 10.8% to 65.6%Single lane roundabouts - exit - rates ranged from 11.8% to 36.1%’Multilane roundabout - average yielding in both lanes, without treatment, ranged from 25.2% to 29.7%
(Geruschat, D.R., & Hassan, S.E. (2005). Driver behavior in yielding to sighted and blind pedestrians at roundabouts. Journal of Visual Impairment and Blindness; National Cooperative Highway Research Program. NCHRP 3-78a. Draft Final Report; Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities; Inman, V. W., Davis, G. W., & Sauerburger, D. (2005). Pedestrian access to roundabouts: Assessment of motorist yielding to visually impaired pedestrians and potential treatments to improve access)
Accessible Design for the Blind, 8/13/2010, Slide
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Blind pedestrians often did not detect vehicles yielding
NEI research – Nashville roundabout Sighted participants took advantage of all 12 yields they were offeredBlind participants crossed on only 9 of the 37 yields they were offered
Sometimes crossed without knowing a vehicle was thereSometimes perceived the yield but didn’t know about other vehiclesDrivers frustrated / irritated when blind participants did not take the yield
(Guth, D., Ashmead, D., Long, R., Wall, R., & Ponchillia, R. (2005). Blind and sighted pedestrians’ judgments in gaps in traffic at roundabouts. Human Factors, 47, 314–331.)
Accessible Design for the Blind, 8/13/2010, Slide
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NCHRP 3-78a Research Study Design
Pre-post within-subject with treatment installationOrientation and Mobility (O&M) familiarization and supervision throughout trialsIndependent crossings (with O&M)Blind participants could stop participation at any time
Accessible Design for the Blind, 8/13/2010, Slide
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Evaluation of Single-Lane Roundabouts
• Three sites tested• Three different cities• No treatments
installed• Varying geometries • Range of volumes• Different participants
and driving culture
Accessible Design for the Blind, 8/13/2010, Slide
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Single-Lane Roundabout Results
Tested single-lane roundabouts appear to not pose unreasonable crossing difficulties to most blind travelers, provided that
Speeds are low through good roundabout designDrivers are courteous and yield the right-of-wayAppropriate detectable warnings are installedBlind travelers receive orientation and mobility instruction specific to roundabout crossings
Accessible Design for the Blind, 8/13/2010, Slide
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Two-Lane RoundaboutGolden Rd. @ Johnson Rd., Golden, CO
Accessible Design for the Blind, 8/13/2010, Slide
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Two treatments
Raised crosswalkPedestrian Hybrid Beacon (previously called HAWK)
Accessible Design for the Blind, 8/13/2010, Slide
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Two-Lane RBT Findings
Two-lane roundabouts are challenging without additional treatments
Speed and volumes are higherMultiple-threat situations are biggest risk
Treatments proved effective in reducing speeds, increasing yields, and creating crossing opportunitiesTreatments reduced delay and interventions (risk)
Raised crosswalk exhibited more multiple threat and (perceived) risk than PHB
Accessible Design for the Blind, 8/13/2010, Slide
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The NCHRP 3-78a Final Report
… establishes common “language” and performance measures for ongoing accessibility debate… contains field data for twelve studies at five intersections, 56 blind participants, and 3300 crossing attempts… presents an initial assessment of new crossing treatments, particularly for two-lane roundabouts… provides ways to extend the research results through statistical modeling and simulation… establishes a baseline for future research in this area to assure compatibility of results
The report does not give warrants or requirements for treatment installation
Accessible Design for the Blind, 8/13/2010, Slide
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Research status
NCHRP 3-78a completed; final report available when NCHRP publishes itFHWA research completed in 2006; report available online (Inman, Davis, Sauerburger)Several articles published on NEI research; research is continuing
Testing treatments at 3-lane roundabouts in Michigan (with financial assistance from Oakland County)Quiet car issuesWayfinding issues
Accessible Design for the Blind, 8/13/2010, Slide
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Research Needs
Additional treatment testing at two-lane roundabouts to increase sample size and build confidence in treatment effectivenessSupplemental data for single-lane roundabouts to understand relationship of design and traffic volumes to accessibilityDevelopment of improved measures to quantify pedestrian risk
Accessible Design for the Blind, 8/13/2010, Slide
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More information
www.itre.ncsu.edu/ITRE/research/Pedestrian-Accessibility/index.html www.tfhrc.gov/safety/pedbike/pubs/05080/