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					 Pedestrians
who are blind
     at
Roundabouts



          Janet Barlow, COMS
         Accessible Design for the Blind
                FHWA Webinar
                August 13, 2010
Transportation choices for individuals
who are blind or who have low vision
    Walk
    Public transit - Bus or rail
    Paratransit services
    Taxis or shuttles
    Rides from friends or relatives
    Paid drivers


                       Accessible Design for the Blind, 8/13/2010, Slide 2
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


                        Accessible Design for the Blind, 8/13/2010, Slide 3
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 4
Aids and techniques for obstacle
       and curb detection
   Long white cane
     Used as a probe
     of the walking
     surface
     May identify
     person as
     visually
     impaired

                       Accessible Design for the Blind, 8/13/2010, Slide 5
Aids and techniques for obstacle
       and curb detection
   Dog guide
     Guides around
     obstacles
     Stops 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 6
Orientation and alignment cues
   Slight slopes and changes in surface
   textures
   Sidewalk and/or grass line or building
   line
   Traffic – both parallel to travel path and
   perpendicular to travel path
   Other pedestrians, sun, other cues
   Awareness of intersecting streets and
   general layout of area
                      Accessible Design for the Blind, 8/13/2010, Slide 7
         Crossing cues
Signalized
  Traffic stopping on the street that the
  pedestrian is planning to cross
  Vehicles starting and moving across the
  intersection in the closest through lane
Unsignalized
  Hearing a vehicle approaching
  Not hearing any vehicles
  Hearing a vehicle yielding
  Traffic moving parallel to crosswalk

                      Accessible Design for the Blind, 8/13/2010, Slide 8
     Wayfinding issues
Recognizing
that the
intersection is
a roundabout

Locating
crosswalks
Aligning to
cross
                  Accessible Design for the Blind, 8/13/2010, Slide 9
Locating crosswalks




                          Where blind
                           pedestrian
                         might cross (if
                         unaware that’s
                             it’s a
                          roundabout)
          Accessible Design for the Blind, 8/13/2010, Slide 10
Finding proper crossing location




            Have to turn before intersection
                          Crosswalk


                  Accessible Design for the Blind, 8/13/2010, Slide 11
Finding proper crossing location




                                  Or continue around
                                  the corner




                Accessible Design for the Blind, 8/13/2010, Slide 12
Wide curb ramp may be mistaken for
driveway; also wider than crosswalk




                  Accessible Design for the Blind, 8/13/2010, Slide 13
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 14
Potential treatments – wayfinding
    Design of
    sidewalk
    Tactile
    features or
    fences
    Sound cues
    from audible
    signals

                   Accessible Design for the Blind, 8/13/2010, Slide 15
Issues with determining when to cross
     Detecting a gap in traffic
     Detecting that vehicle has yielded

     For pedestrians who are blind, research
     has documented
       latency and delay in detecting gap or yield,
       and subsequent inability to cross
       unsafe judgments about gaps or yields

                          Accessible Design for the Blind, 8/13/2010, Slide 16
Detecting a gap, or yield
Using hearing alone, it is not always
possible to pinpoint direction of sound
  not as specific as vision
  cannot select just one lane or area to check
One vehicle can mask the sound of
others approaching, possibly closer
Quieter cars further complicate this
problem
                    Accessible Design for the Blind, 8/13/2010, Slide 17
Latency and delay in detecting gaps
                              6


                                                blind   sighted
                              5
       Mean gap detection latency (sec)

                              4




                              3




                              2




                              1




                              0


                                          Entry lane                           Exit lane

                                                        Accessible Design for the Blind, 8/13/2010, Slide 18
       Sound masking
Vehicles that have just passed the crosswalk
Vehicles in the circulatory roadway
Vehicles 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

                    Accessible Design for the Blind, 8/13/2010, Slide 19
      Sound masking
Vehicles on nearby bridges/expressways
Other sounds in the environment
  Lawnmowers
  Nearby construction
  High ambient noise




                   Accessible Design for the Blind, 8/13/2010, Slide 20
  Pedestrian who is blind cannot
safely assume that drivers will yield




                   Accessible Design for the Blind, 8/13/2010, Slide 21
 Driver yielding behavior
NEI research – Maryland roundabout
    Likelihood of yielding diminishes with increasing speed
    White cane has only modest impact on yielding behavior
    At 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 yielded
NCHRP 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 22
Blind pedestrians often did not detect
          vehicles yielding
   NEI research – Nashville roundabout
     Sighted participants took advantage of all 12 yields they
     were offered
     Blind participants crossed on only 9 of the 37 yields they
     were offered
         Sometimes crossed without knowing a vehicle was there
         Sometimes perceived the yield but didn’t know about other
         vehicles
         Drivers 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 23
NCHRP 3-78a Research Study Design
   Pre-post within-subject with treatment
   installation
   Orientation and Mobility (O&M)
   familiarization and supervision
   throughout trials
   Independent crossings (with O&M)
   Blind participants could stop
   participation at any time
                     Accessible Design for the Blind, 8/13/2010, Slide 24
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 25
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
     design
     Drivers are courteous and yield the right-of-way
     Appropriate detectable warnings are installed
     Blind travelers receive orientation and mobility
     instruction specific to roundabout crossings

                        Accessible Design for the Blind, 8/13/2010, Slide 26
     Two-Lane Roundabout
Golden Rd. @ Johnson Rd., Golden, CO




       Accessible Design for the Blind, 8/13/2010, Slide 27
      Two treatments
Raised crosswalk
Pedestrian Hybrid Beacon (previously
called HAWK)




                 Accessible Design for the Blind, 8/13/2010, Slide 28
Raised Crosswalk




        Accessible Design for the Blind, 8/13/2010, Slide 29
Pedestrian Hybrid Beacon




            Accessible Design for the Blind, 8/13/2010, Slide 30
 Two-Lane RBT Findings
Two-lane roundabouts are challenging
without additional treatments
  Speed and volumes are higher
  Multiple-threat situations are biggest risk
Treatments proved effective in reducing
speeds, increasing yields, and creating
crossing opportunities
Treatments 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 31
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 32
      Research status
NCHRP 3-78a completed; final report
available when NCHRP publishes it
FHWA 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 issues
  Wayfinding issues

                     Accessible Design for the Blind, 8/13/2010, Slide 33
      Research Needs
Additional treatment testing at two-lane
roundabouts to increase sample size and
build confidence in treatment effectiveness
Supplemental data for single-lane
roundabouts to understand relationship of
design and traffic volumes to accessibility
Development of improved measures to
quantify pedestrian risk

                   Accessible Design for the Blind, 8/13/2010, Slide 34
    More information
www.itre.ncsu.edu/ITRE/research/Pedest
rian-Accessibility/index.html
www.tfhrc.gov/safety/pedbike/pubs/050
80/

www.accessforblind.org
jmbarlow@accessforblind.org

                 Accessible Design for the Blind, 8/13/2010, Slide 35

				
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