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Pedestrians with Vision Loss or Blindness

(Slide 1)

How many people are blind or visually impaired now (Slide 2)

• 4.3 million Americans are severely visually impaired
• 1.1 million are legally blind
• Incidence increases with age

By 2010, expect there to be 20 million visually impaired persons over age 45

Variations in Vision Loss (Slide 3)

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How do pedestrians who are blind or visually impaired travel? (Slide 9)

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 (Slide 10)

• Transportation choices
  • Walk
  • Bus or rail transit
  • Taxis, friends, relatives, or paid drivers

Obstacle detection and curb detection techniques (Slide 11)

• Long white cane used as a probe of the walking surface
• Dog guide to used guide around obstacles or stop at curbs or dropoffs
• Low vision travelers may use their vision and an aid such as a telescope

Orientation and alignment cues (Slide 12)

• Detect slight slopes under foot and/or a detectable change in surface texture
• Listen to direction that cars are traveling to align to cross
• Listen to when the cars start moving in the closest lane as indication of time to cross
• Maintain awareness of buildings, sun, other pedestrians, smells, and sounds which provide information
• Ask a lot of questions

Crossing at a signalized intersection (Slide 13)

Problem areas for travelers who are blind (Slide 14)

• Locating the crosswalk
• Detecting a gap in traffic

Locating the crosswalk (Slide 15)

• Preventing crossing into the circulatory roadway
• Finding the crosswalk
• Aligning to cross

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Australia (Slide 21)

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Detecting a gap in traffic (Slide 23)

• Hearing is not as specific as vision
• With vision, can select just one lane or area to check; not possible when crossing using audible cues only
• Pedestrians with low vision may have more difficulty with depth perception and judging speed

Masking by other cars (Slide 24)

• Cars that have just passed the crosswalk
• Cars in the circulatory roadway
• Car approaching in other lane of street the pedestrian is crossing
• Car that stops to allow the pedestrian to cross (multi-lane roundabout)

Sighted pedestrian crossing (Slide 25)

Blind pedestrian crossing (Slide 26)

Ongoing Research (Slide 27)

• National Eye Institute of the National Institutes of Health has funded a five year project on Blind Pedestrians' Access to Intersections
  • Roundabouts - blind and low vision individuals
  • Accessible Pedestrian Signals
  • Detectable warnings
• June 2000 - May 2005

NEI-Supported Study of Roundabouts Access (Slide 28)

• To date
  • Evaluated gap judgments by sighted and blind individuals at 5 roundabouts with volumes from 12,000 to 35,000 estimated AADT
  • 2 Single lane and 3 multi-lane

NEI study - Traffic Volume (Slide 29)

• Higher volumes yielded fewer crossable gaps
• Higher volumes resulted in more unsafe judgments, more missed gaps, and longer periods of time between the beginning of a crossable gap and the point at which a blind person detected it

NEI study - Unsafe judgments (Slide 30)

• Blind participants were more than twice as likely to make unsafe judgments as sighted participants
• Time of day differences
  • Little difference between judgments of blind and sighted individuals at mid-day
  • Substantial differences at rush hour

NEI study - Latency and delay

• Blind pedestrians detected gaps later than sighted pedestrians
  • Baltimore - 3 seconds later
  • Tampa - 5.5 seconds later
• Blind pedestrians require longer gaps in order to detect the gap and cross

Experience in other countries

• Reports from pedestrians who are blind or visually impaired indicate that roundabouts are often considered a barrier to independent travel

Australia

• Individuals who are blind or visually impaired and Orientation and Mobility Specialists state that blind pedestrians
  • Avoid crossing at roundabouts
  • Often severely limit where they can travel
• Roundabouts there may have detectable warnings and tactile guidestrips

England

• Pedestrians who are blind or visually impaired state that roundabouts can be very difficult to cross
• Signals are installed at some roundabout locations, as are raised crosswalks

Review - Problem areas

• Difficulty finding appropriate location to begin crossing
• Latency and delay in detecting gap, and subsequent inability to cross
• Unsafe judgments about gaps