pedestrians who are blind at roundabouts

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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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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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


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


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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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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Wayfinding issues

Recognizing that the intersection is a roundabout

Locating crosswalksAligning to cross


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Locating crosswalks

Where blind pedestrian might cross (if unaware that’s it’s a roundabout)


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Finding proper crossing location

CrosswalkHave to turn before intersection


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Finding proper crossing location

Or continue around the corner


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Wide curb ramp may be mistaken for driveway; also wider than crosswalk


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Landscaping could have been used to guide person to crosswalk and to help them align

to cross


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Potential treatments – wayfinding

Design of sidewalkTactile features or fencesSound cues from audible signals


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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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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Latency and delay in detecting gaps

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1

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Entry lane Exit lane

Mea

n ga

p de

tect

ion

late

ncy

(sec

) blind sighted


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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Sound masking

Vehicles on nearby bridges/expresswaysOther sounds in the environment

LawnmowersNearby constructionHigh ambient noise

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Pedestrian who is blind cannot safely assume that drivers will yield


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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)


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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.)


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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


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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


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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


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Two-Lane RoundaboutGolden Rd. @ Johnson Rd., Golden, CO


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Two treatments

Raised crosswalkPedestrian Hybrid Beacon (previously called HAWK)


Raised Crosswalk

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Pedestrian Hybrid Beacon

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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


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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


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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


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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


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More information

www.itre.ncsu.edu/ITRE/research/Pedestrian-Accessibility/index.html www.tfhrc.gov/safety/pedbike/pubs/05080/

[email protected]

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