Truncated Dome Detectable Warnings Traffic control device

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Truncated Dome Detectable Warnings Traffic
control device?

• Janet M. Barlow
• Accessible Design for the Blind
• January 2004

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Detectable Warnings Tactile Stop Line

• Provides information to the pedestrian who is
  blind or visually impaired about the location of
  the edge of the street

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Need for detectable warnings

• Research in 1992 on pedestrians who are blind at
  curb ramps
• 48 of participants walked into the street when
  they approached on a curb ramp of 112 or less
• Confirmed by additional research in 1995

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What is detectable?

• Truncated dome surface
• the only surface found to be reliably detected on
  most trials by blind pedestrians, both under foot
  and by the use of a long cane

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Detectable, under foot and with cane

• Truncated dome pattern and texture

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Terminology

• Detectable warning is the defined term in
  Americans with Disabilities Act Accessibility
  Guidelines
• A standardized surface feature built in or
  applied to walking surfaces or other elements to
  warn of hazards on a circulation path.

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Curb ramps
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Diagonal curb ramp
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Curb ramp
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Blended curb location
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Curb ramp, in line with crossing
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Curb ramp - Australia
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Curb ramps at curb extensions
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Median island
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Median island - Europe
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Raised crosswalk
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Traffic Control Device??
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Definition of Traffic Control Devices

• All signs, signals, markings, and other devices
  used to regulate, warn, or guide traffic, placed
  on, over, or adjacent to a street, highway,
  pedestrian facility, or bicycle path by authority
  of a public agency having jurisdiction.

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Definition of Traffic

• Pedestrians, bicyclists, ridden or herded
  animals, vehicles, streetcars, and other
  conveyances either singularly or together while
  using any highway for purposes of travel.

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Section 1A.01 Purpose of Traffic Control Devices

• Support..Traffic control devices notify road
  users of regulations and provide warning and
  guidance needed for the safe, uniform, and
  efficient operation of all elements of the
  traffic stream. (emphasis added)

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Proper Use

• The proper use of traffic control devices should
  provide the reasonable and prudent road user with
  the information necessary to safely and lawfully
  use the streets, highways, pedestrian facilities,
  and bikeways (emphasis added)

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Why Markings?

• 3A.01 Functions and Limitations
• markings are used alone to effectively convey
  regulations, guidance, or warnings in ways not
  obtainable by the use of other devices

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3A.01 Continues..

• ..Pavement markings can enhance roadway
  delineation with the addition of audible and
  tactile features (emphasis added), such as bars,
  differential surface profiles, raised pavement
  markers, or other devices intended to alert the
  road user that a delineation on the roadway is
  being traversed.

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Detectable warnings

• Traffic control device?.Yes
• Markings?..Yes