Publicado por: Ricardo Shimosakai | 30/04/2014

Travel Tools and Techniques of People Who are Blind or Who Have Low Vision


Many individuals who are blind or visually impaired use a long white cane as a mobility deviceMany individuals who are blind or visually impaired use a long white cane as a mobility device

Several choices

People who are blind or visually impaired make choices when it comes to traveling. At any given time, they can travel using a human guide, which involves holding onto someone’s arm; using a long, white cane to identify and avoid obstacles or elevation changes; using a dog guide; using special optical or electronic aids; or using no additional aid.

The choice of tools depends on the extent and nature of visual impairment, personal preference, lighting, and familiarity with the area.

In order to travel independently, people with visual impairments use whatever vision they have, auditory and tactual information, and any gathered knowledge of an area to keep track of their location and make travel decisions.

Human Guide (sometimes referred to as Sighted Guide)

At one time or another, most people who are blind will make use of the human guide technique, in which a person with sight serves as a guide to a person who is blind or visually impaired.

Long white cane

Many individuals who are blind or visually impaired use a long white cane as a mobility device. In the most common technique, the cane is extended and swung back and forth across their body in rhythm with their steps to provide information about the environment directly in front of them, such as elevation changes or obstacles. In another technique often used by people with low vision, the cane is held diagonally across their body, with the tip about an inch above the ground. When those individuals are unsure about what they are seeing, they usually check the object or sidewalk surface with their cane.

Dog guide

Dog guides are carefully trained service animals used as travel tools by approximately 2% of people who are blind. The dog responds to the commands of its handler, such as right, left and forward. The dog guides the handler around obstacles and stops at curbs or stairs. However, the handler must know where they are going and make decisions about the proper time to begin a street crossing. Dog guides move in response to directions from their handlers but may disobey commands to avoid danger.

No aid

Not all persons considered blind use a long white cane or dog guide. People who are visually impaired often rely on their remaining sight and auditory and tactile cues in their surroundings for orientation and travel. Some may also use aids such as telescopes for specific tasks.

Orientation and mobility training

Many pedestrians who are visually impaired or blind have received orientation and mobility training, provided by an Orientation and Mobility (O&M) Specialist. O&M Specialists usually have an undergraduate or graduate degree in teaching travel skills to persons who have visual impairments.

Orientation is the ability to understand where one is located in space and Mobility refers to being able to travel through that space safely. The goal of most O&M training is to prepare a person who is visually impaired to travel in a variety of environments, both familiar and unfamiliar, and to assess new intersections and travel new routes. It is important to note that orientation training and assistance is not provided for every route that a person who is blind needs to travel.

How People Who are Blind or Visually Impaired Cross Streets

Traditional techniques

Techniques and cues used in crossing streets are diverse and vary by the type of location and by the individual and his or her level of vision. Individuals who are blind or visually impaired often travel to unfamiliar areas and intersections and gather information from available sources in order to do so safely.

The discussion of techniques below describes typical techniques used at unfamiliar intersections, although most travel by pedestrians who are blind is probably on routes with which they are familiar. However, it is also not uncommon for bus drivers or taxi drivers to provide incorrect information about the location or drop off a person at a slightly different location than expected, so it is necessary to regularly confirm information using nonvisual techniques described below.

Once pedestrians who are blind are familiar with an intersection, they do not usually need to analyze the intersection and traffic control system at length every time. However, they still may need to listen long enough to determine that they are at the correct location and that the signal is functioning as usual. Pedestrians who are blind will still need to detect the street, align to cross, identify the WALK interval, and maintain alignment while crossing. APS can particularly assist with the task of identifying the WALK interval at familiar and unfamiliar locations.

Detecting the street

The first information needed by pedestrians who are blind is “Have I arrived at a street?” People who are blind or visually impaired use a combination of cues to recognize the street edge. These may include:

  • Curb or the slope of the ramp
  • Truncated dome detectable warnings, if available
  • End of building line and open sound of the intersection
  • Sound of traffic on the street beside them (the parallel street)
  • Sound of traffic stopping on the street they are approaching (the perpendicular street)
  • Presence of pedestrians
  • Presence of an intersecting sidewalk

Identifying the street

The next information needed for decision-making at unfamiliar intersections is: “Which street is this?”

  • This information is only occasionally provided in any accessible format.
  • Pedestrians who are visually impaired develop a mental map and keep track of where they are within that map, usually by counting blocks and street crossings.
  • Where necessary, and available, assistance may be sought from other pedestrians.

Analyzing intersection geometry

The next information needed is: “What is the geometry of this intersection?” including:

  • Is my destination curb straight in front of me, or must I angle to the left or right to reach it?
  • How many streets intersect here?
  • How wide is this street?
  • Should I expect to encounter any islands or medians as I cross this street?
  • Am I standing within the crosswalk?

This information may be immediately available to pedestrians having full vision, but it may not be possible for pedestrians who are blind to determine this information by listening to traffic patterns. Incorrect or missing information for any of these questions may result in missing the destination curb or median.

Analyzing the traffic control system

Next, pedestrians with visual impairments need to know: “What is the type of traffic control system at this intersection?”, including:

  • Is this a signalized intersection?
  • Do I need to push a button to actuate the WALK interval? If so, where is the button?
  • Is the button close enough to the crosswalk that I will have time to push the button, position myself correctly at the crosswalk, and reestablish my alignment facing the destination curb before the onset of the WALK interval?
  • Which button controls the WALK interval for the street I want to cross?
  • Does it stop traffic on one street, or all traffic?
  • Do cars still turn during the WALK interval?
  • Is there a second button on the median or crossing island that I must push?
  • Will there be a surge of parallel traffic telling me the WALK interval has begun? Will I be able to hear it over other, concurrent traffic sounds?

Techniques for gathering this information include listening to traffic patterns through several signal cycles and searching the sidewalk area for poles with pushbuttons. Missing information for any of these questions may result in failure to use pedestrian pushbuttons, not beginning the crossing during the WALK interval, not completing the crossing before perpendicular traffic begins moving, and crossing at times other than the pedestrian phase.

Aligning to cross

Before starting to cross, the pedestrian must align to cross or choose a heading for the crossing. Typical techniques for this task include maintaining the alignment used on the approach to the intersection and listening to parallel traffic through a signal cycle to confirm alignment to parallel traffic. The need to use pedestrian pushbuttons often prevents the use of parallel traffic for alignment. After pushing the button, the pedestrian must cross on the next pedestrian phase, which is usually the next time that traffic begins moving parallel to the pedestrian’s crosswalk.

Identifying the WALK interval

After determining the geometry of the intersection, aligning to face towards the destination curb, determining that the intersection is signalized and having pushed a button, where necessary, pedestrians who are blind need to know: “When does the WALK interval begin?”

In the most common technique utilized for crossing at signalized intersections, pedestrians who are blind or visually impaired begin to cross the street when there is a surge of traffic on the street parallel to their direction of travel. This technique is dependent upon the presence of traffic and consistent signal phasing. Various types of phasing and intermittent or low volumes of traffic traveling parallel to the pedestrian may affect the reliability of that technique.

Maintaining crossing alignment

Once the pedestrian who is blind has begun to cross the street, the next question is: “Am I headed straight towards my destination curb?”

  • Traffic going in the same direction on the parallel street provides helpful auditory guidance to many persons if it is present. In addition, pedestrians who are blind may use traffic waiting on the perpendicular street as a partial alignment cue.
  • Turning traffic can make it difficult to hear and align with the traffic traveling straight through the intersection.

In the absence of traffic on the parallel street, pedestrians who are blind are more likely to veer toward or away from the intersection.

Source: Accessible Pedestrian Signals


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