Needs and Requirements of Blind Pedestrians at Signalized Intersections

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Needs and Requirements of Blind Pedestrians at
Signalized Intersections

• Workshop on Accommodating Pedestrians at
  Signalized Intersections
• Janet M. Barlow
• Accessible Design for the Blind
• January 11, 2009

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Blind may not mean totally blind
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Intersection as seen by someone with normal
vision
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Central vision loss
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Peripheral Vision Loss
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Overall acuity loss
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Totally blind
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How do people who are blind or who have low
vision travel?

• Sighted (human) guide
• White cane
• Dog guide
• Telescope or other low vision aids
• No aid

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Pedestrians who are blind or who have low vision

• May travel to unfamiliar destinations for
  shopping, errands, visiting friends, childrens
  activities, work, or other purposes, just like
  those who are fully sighted
• May have to figure out intersections and
  intersections crossings when they arrive at them

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Street crossing tasks

• Locate edge of the street
• Determine where to begin crossing (locate
  crosswalk)
• Establish crossing direction and alignment
• Determine traffic control and use pushbutton, if
  necessary
• Decide when to begin crossing
• Maintain alignment during crossing

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Traditional strategies

• Walk up to corner
• Maintain travel direction
• Listen through a signal cycle
• Cross with the surge of traffic traveling
  parallel to crosswalk
• Maintain direction by listening to vehicles and
  other cues

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Problems in the current intersection environment

• Curb ramps
• Rounded corners (large radius)
• Wide streets
• Complex intersection geometry
• Actuation and complex signalization
• Need to use pedestrian pushbutton

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Street crossing tasks

• Locate edge of the street
• Determine where to begin crossing (locate
  crosswalk)
• Establish crossing direction and alignment
• Determine traffic control and use pushbutton, if
  necessary
• Decide when to begin crossing
• Maintain alignment during crossing

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Locate edge of the street

• Detectable warnings
• Also called truncated domes or truncated dome
  detectable warnings
• Required on curb ramps or blended transitions
  at crossings
• Not yet installed everywhere

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NOT detectable warnings
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Detectable warning
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Detectable warning at curb ramps
24 in direction of travel at back of curb Full
width of ramp or level area
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Street crossing tasks

• Locate edge of the street
• Determine where to begin crossing (locate
  crosswalk)
• Establish crossing direction and alignment
• Determine traffic control and use pushbutton, if
  necessary
• Decide when to begin crossing
• Maintain alignment during crossing

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Crosswalk in line with sidewalk
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Crosswalk offset from corner can be problematic
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May not cross at crosswalk
Adding planter strip could help
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Street crossing tasks

• Locate edge of the street
• Determine where to begin crossing (locate
  crosswalk)
• Establish crossing direction and alignment
• Determine traffic control and use pushbutton, if
  necessary
• Decide when to begin crossing
• Maintain alignment during crossing

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Crossing direction and alignment

• Still working on solutions
• Detectable warnings dont provide alignment info
• Ramp design
• Two ramps per corner where possible
• Align ramp with travel direction
• BUT.requirement for ramp to be perpendicular to
  the curb and gutter requires ramp to angle toward
  the street at large radius corners
• Provide edge that is aligned with travel
  direction?
• Sound of accessible signal may provide alignment
  information

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Example of curb ramp designs that provide
alignment cues
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Pedestrian pushbuttons can also affect alignment

• Have to deviate to push button
• Must cross on next pedestrian phase
• cant listen to parallel traffic phase to realign

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Street crossing tasks

• Locate edge of the street
• Determine where to begin crossing (locate
  crosswalk)
• Establish crossing direction and alignment
• Determine traffic control and use pushbutton, if
  necessary
• Decide when to begin crossing
• Maintain alignment during crossing

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Pedestrian Pushbuttons

• Is there a pushbutton?
• Where is it?
• Have I found the pushbutton for the street Im
  crossing?

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Decide when to begin crossing

• Traditional cues to time to cross
• Stopped traffic on cross street
• Surge of traffic in parallel lane closest to
  crosswalk

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Traffic cues may not be available where there are

• Low volumes of traffic parallel to crosswalk
• Crossing major street
• T intersections (crossing top of T)
• Heavy turning traffic volumes
• Exclusive pedestrian phases
• Leading pedestrian phases

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Newer type of Accessible Pedestrian Signals (APS)

• Features provide information about pushbutton and
  pedestrian signal indications
• Pushbutton Locator tone
• Audible and Vibrotactile Walk indications
• Tactile arrow
• Automatic volume adjustment

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Speakers at the pushbutton
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Pushbutton Locator Tone

• Sound comes from the pushbutton
• Provides information about pushbutton presence
  and location
• 1 tone per second, each tone less than 0.15
  seconds in duration
• Volume set to be heard within 6 12 feet, or at
  the building line, whichever is less
• Different sounds acceptable (click, beep, etc)

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Tactile arrow

• Raised arrow
• May be on the pushbutton, on part of the device,
  or on sign above the pushbutton
• aligned with direction of travel on the
  crosswalk controlled by the pushbutton

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Tactile Arrow examples
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Recommended WALK indications

• A rapid tick WALK indication (sound on slide 6)
  at locations where the speakers for APS for two
  different crosswalks are separated by at least 10
  feet
• Vibrotactile WALK indication - arrow (or other
  surface on pushbutton unit) that vibrates during
  WALK

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Pushbutton-integrated APS

• Continuous pushbutton locator tone with rapid
  tick WALK indication

Sounds attached click on photo to hear sounds
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Pushbutton-integrated APS

• Continuous pushbutton locator tone followed with
  speech walk indication

Sounds attached click on photo to hear sounds
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Automatic volume adjustment

• Volume of pushbutton locator tone and audible
  walk indications adjusts in response to ambient
  sound
• Louder when traffic is loud or there is other
  noise at the intersection
• Quiet when traffic or other sounds are quieter
  (night)

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APS Location is critical

• Provide information to the user through proximity
  to the departure point
• Signal can be quieter due to proximity

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Installation recommendations

• Beside the landing of the curb ramp
• Separated by more than 10 feet from other APS on
  corner
• MUTCD says within 5 feet of crosswalk line and
  within 10 feet of the curb

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Installation example - APS separated by 10 feet
(3m)

• Reachable from level landing, within 10 ft of
  curb, within 5 feet of crosswalk lines

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Installation example - APS aligned with crosswalk
lines
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Street crossing tasks

• Locate edge of the street
• Determine where to begin crossing (locate
  crosswalk)
• Establish crossing direction and alignment
• Determine traffic control and use pushbutton, if
  necessary
• Decide when to begin crossing
• Maintain alignment during crossing

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Maintaining alignment

• Listen to traffic, waiting and moving
• Road slope and camber

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Features that help pedestrians who are blind

• Simple geometry
• Shorter crossings
• Landscaping or barriers to direct to crossing
  location and prevent crossing at the wrong place
• Curb ramp that is aligned as closely as possible
  to direction of travel on the crosswalk
• Detectable warning at street edge and edge of
  splitter island cut-throughs
• Raised splitter islands with edges aligned in
  crosswalk travel direction
• Accessible pedestrian signals, with new features,
  for crossings

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Modifications that make intersections accessible
to pedestrians who are blind are helpful to ALL
pedestrians
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Acknowledgements

• Some photos courtesy of Lukas Franck, Michael
  Ronkin, Lois Thibault, and Billie Louise (Beezy)
  Bentzen
• Graphics from Accessible Pedestrian Signals A
  Guide to Best Practice

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Questions??For more information, contact

• Janet M. Barlow
• Accessible Design for the Blind
• 770-317-0611
• jmbarlow_at_accessforblind.org