1998 Conference Proceedings

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Bill Crandall, Ph.D.
Smith-Kettlewell RERC
2232 Webster Street
San Francisco, CA. 94115

B.L. Bentzen, Ph.D.
Accessible Design for the Blind

Linda Myers, M.Ed.
Marin County (CA) Public Schools

The most common signage for people who are blind is restricted to tactile displays. This requires persons to be at the location of the signs before they can identify the information it bears. Using such signage as an aid in locating and traveling to a telephone booth, bus stop, elevator, public electronic terminal, building entrance or exit, leads to the paradoxical effect of having to already be there before one knows where it is. In addition to the problem of locating specific travel goals, very often blind travelers are unaware of the many amenities that sighted travelers encounter in a purely serendipitous fashion.

Remote Infrared Signage is particularly appropriate for open spaces where tactile signs are inappropriate; they label the environment for distant viewing. Remote infrared signs allow people to directly know not only "what" choices are available to them, but "where" in the environment these options are. Just as sighted persons visually scan the environment to acquire both label and direction information, remote infrared signs directly orient the person to the labeled goal and constantly update the person as to his progress to that goal. That is, unlike Braille, raised letters, or voice signs which passively label some location or give mobility instructions to some goal, remote infrared signage provides a repeating, directionally selective voice message which originates at the sign and is transmitted to a hand-held receiver. The direction selectivity is a characteristic of the infrared message beam and ensures that persons using the device gets constant feedback about their relative location to the goal as they move towards it.

An analysis of the National Center for Health Statistics estimated that 4.3 million non-institutionalized people in the US had difficulty reading the newspaper with their corrected vision -- a functional definition of perceived limitations termed Severe Visual Impairment (Nelson and Dimitrova, JVIP, March, 1993). An additional 2.3 million people also reported difficulty with seeing medium to far distances. Another recent study (Chiang, et. al., Milbank Quarterly, 1992) estimates 1.1 million people are Legally Blind under the definition of tested acuity (<20/200). Data from the Bureau of the Census put the figure for this same level of impairment at 9.7 million people (McNeil, 1993). Many other disabilities prevent persons from reading print. In addition to people who are blind or have low vision and may not be able to see the print, there are many stroke, head-injured, autistic and dyslexic (or even just educationally impaired) persons who may not be able to assimilate printed language even though they can see the page. Many people can accept this information through speech. During the past three years of human factors research we have established that blind people using Talking Signs can easily learn to use the system effectively.

Transit Stations:

Transit stations present unique challenges to people who are print disabled; they must visit specific points along potentially crowded and complex paths of travel having no signs which are legible to them, in order to successfully navigate from street entrances to the proper train. Such a course involves the challenge of identifying the correct entrance, change and ticket machines, station agent kiosks, entry gates, escalators, steps and elevators onto the platform, a specific platform area and specific train or coach.

Previous research indicates that Talking Signs users independently learned many characteristics of the system which we did not specifically teach them in the short training preceding test trials. Ease of use, learning to scan, ease of picking up messages, and following the sign to the destination are thought to be related to the level of training and indicate a need to evaluate training requirements for effective and safe use of Talking Signs. The present study, therefore focused on the question: "What is the minimum amount of training required for a person to effectively and safely use the Talking Signs system?" To answer this question, we evaluated the travel characteristics of 36 visually impaired people who used the Talking Signs system as an aid to navigation through a complex subway station in downtown San Francisco (Powell Station) for the Bay Area Rapid Transit (BART) and the San Francisco Municipal Railway (Muni). The broad cross section of subjects was divided into three groups, each group being matched for varying levels of mobility skills, degree of residual vision, and method of travel (guide dog or cane), presence of hearing impairment, and level of spatial thinking. Each group received a different level of training on the proper use of the system.

From our results it is clear that persons having visual impairments are readily able to learn to use the Talking Signs system for the wayfinding information necessary for traveling routes in a transit station without assistance. Within the limits of the one hour test period, of 36 participants traveling routes without aid, 35 successfully completed at least two easy routes 23 successfully completed at least two medium routes (plus all easy routes) and 17 successfully completed at least two hard routes Plus all easy routes and all hard routes). It appears that training enabled participants who were more highly trained to complete more complex routes. This finding was not statistically significant, however. Even the minimal level of training in which participants received written instructions in their preferred medium, enabled many participants to successfully travel routes in a complex transit environment in which they were given no information other than that available from the Talking Signs, themselves.

Surface Transit and Buses:

In the absence of Talking Signs transmitters, there are two primary ways which blind travelers use to find unfamiliar bus stops. The first is to ask another pedestrian, if one can be found, and the second is to laboriously look from one end of a block to the other, bearing in mind that stops may be at the beginning, middle or end of a block, may or may not be marked by a pole, may or may not have shelters, and shelters may be along either the curb side or at the building line away from the curb. In order to locate a particular bus of many which are parked along a curb, the blind pedestrian must hurry from one door to the next, asking the bus driver or waiting passengers the identity of each bus.

Locating and Identifying Bus Stops: Eighteen blind participants located and identified bus stops using either the Talking Signs system plus their usual mobility skills or their conventional strategies, including tactile signs, but without asking for assistance. They then located and identified a particular bus out of three lined up along a curb using either their normal procedure of asking the driver or using the Talking Signs system. Participants were generally more successful in locating and identifying bus stops using the Talking Signs system than using tactile signs, particularly when the bus stop was identified only by a pole-mounted sign rather than a bus shelter. Participants using dog guides had particular difficulty in the absence of the Talking Signs system.

Identifying Buses en masse: In order to locate a particular bus of many which are parked along a curb, the blind pedestrian must hurry from one door to the next, asking the bus driver or waiting passengers the identity of each bus.

Success on the bus identification task was high regardless of whether the bus was labeled with the Talking Signs system or not, with only 9 failures on 108 attempts to locate the correct bus within one minute. There were also no significant differences in times to locate the bus using the two methods. However, subjects thought that because there were no physical obstacles, either people or newspaper racks interfering with walking near the edge of the sidewalk directly to the door of the bus, the experimental set-up for locating buses represented an unrealistically easy task for the "no Talking Signs" condition. That is, subjects volunteered that under more typically challenging conditions, the Talking Signs system would make identifying and locating buses much easier. There was, perhaps a statistical "ceiling effect" on this task.

When, during the Focus Group, participants were asked to choose between labeling bus stops with Talking Signs transmitters and labeling with tactile signs, all eight participants preferred the Talking Signs system. The tactile signs were considered helpful for definite confirmation, however.

Remote infrared audible signage provides wayfinding information for surface transit as it has previously been shown to do for transit stations, thereby enhancing independent use of public transit by persons having visual impairments.

Pedestrian Crossings at Light Controlled Intersections:

Intersection crossing points are the places in any journey where the traveler is most vulnerable to danger, in the form of collisions with passing vehicles which can result in serious injury or death. This significance is widely recognized not only by blind persons themselves, but >by the Orientation and Mobility profession, who spend a good deal of their mobility training time with each client attempting to teach techniques for successful street crossings. At controlled intersections in busy urban areas, many confusing cues are presented to the blind traveler who must rely primarily on traffic sounds to accomplish the task. For example, the usual cue for determining when it is safe to cross in this situation is the detection of traffic beginning to move in the pedestrian's direction of travel and parallel to him. However, anywhere that green arrows allow turns in front of the pedestrian, safety is not assured by this cue. In addition, even for the most experienced traveler, there are certain things which can not be determined by sound, such as the exact width of the street or if a turning island exists. Having access to all of this type of information lowers the risk of making an inaccurate judgment.

Progress has been made in avoiding many of these ambiguities through the deployment of prototype Talking Signs units at signalized intersections in downtown San Francisco. The application involves providing two types of information to pedestrians. The first tells the user where he or she is located; it is comparable to the information posted on the visual signs at each intersection. The repeating message users hear from the speakers of their hand-held receivers when they are walking down the sidewalk is, for example, "Traveling East on the 800 block of Grove Street toward Larkin Street." When users nears the curb, another message is heard through the receiver's speaker. This "pedestrian crosswalk indicator" message tells users the condition of the traffic signal. It repeats, for example "Wait... Larkin Street" or "Walk Sign.... Larkin Street," the particular message depending upon the status of the visual walk/wait sign. Sighted pedestrians also have specific information about the characteristics of an intersection such as turn lane, mid-block crossing, cut-through, island, pedestrian activated 4-way walk signal, free right turning lane, short walk cycle, use of pedestrian activated signal at island for walk signal to cross second half of street, etc. These extended messages which communicate special attributes about an individual intersection can be added to the message (following the street name on the approach message). Alternatively, this additional information may be provided through a different receiver channel.

In determining the effects of Talking Signs on street crossing performance at complex signalized intersections, 20 persons having very little or no vision were asked to cross four complex signalized intersections in the Civic Center area of San Francisco under two conditions: with information provided by Talking Signs, and without information provided by Talking Signs. All crossings were made under normal daytime traffic conditions.

Participants completed the experiment individually, in sessions lasting approximately 90 minutes. Participants received approximately 10 minutes of training in using Talking Signs at intersections before completing the experimental procedure.

Results: Binomial (step) tests were conducted in which each participant was compared with him/her self on each of the above measures at each of the four intersections, in both the Talking Sign and no Talking Sign conditions, and then a statistic was computed to determine the probability that differences between performances using Talking Signs and no Talking Signs were significant.

Participants were more successful on eight of the nine measures when using Talking Signs than when not using Talking Signs. Nineteen of 20 participants were more successful when using Talking Signs than when not using Talking Signs. One participant had the same (nearly perfect) score both with and without Talking Signs. Participants included persons using both long canes and dog guides, persons with and without hearing loss, persons who considered themselves to be good to excellent travelers, and persons who did not consider themselves to be good travelers. The following types of data were obtained by the experimenter as each participant made each crossing.

Safety: Did the participant begin the crossing during the Walk phase of the light cycle?

Precision: Did the participant begin the crossing from within the crosswalk?

Was the participant heading toward the opposite corner when he/she began the crossing?

Did the participant end up within the crosswalk at the opposite corner?

Need for assistance: Did the participant need (request) assistance in finding the crosswalk?

Did the participant need (request) assistance in knowing when the walk phase began?

Did the participant need assistance in safely completing the crossing (either participant's request, or at the initiative of the experimenter when participant was endangered)?

Knowledge: Did the participant know the general shape of the intersection (plus, T, or irregular)?

Did the participant know the nature of traffic control at the intersection? (traffic light, stop sign, or uncontrolled)?

Results show that Talking Signs at intersections significantly improved safety, precision, and independence in street crossing, as well as knowledge of intersections, for good, frequent, independent blind travelers, using a long cane or dog guide, including those with hearing loss. Talking Signs also resulted in improved street crossing for persons who considered themselves relatively poor travelers, and who did not normally travel in unfamiliar areas.

Automated Teller Machines and Fare Machines:

Location and effective use of ATMs and other public terminals (vending machines with displays, kiosks, hi-tech public telephones, and ticket and fare machines) is a significant and rapidly increasing problem for those with visual impairments. An ATM which cannot be located is not an accessible ATM. Perhaps 7% to 14% of all legally blind people read Braille. Of this group who do read Braille, many do not read Grade II Braille, the abbreviated form of Braille specified by the Americans with Disabilities Act (ADA). Therefore, in this application the number of actual customers helped by a Braille instructions are very small. Even if the majority of blind or print handicapped persons did use Braille, the instructions for any transaction are, in our opinion, to complex to memorize and therefore must be read while on the street at the ATM. Without feedback from the display, users have no indication as to whether the ATM has accepted the PIN code as being proper. Similarly, there is no indication that subsequent entries are operating under the desired menus (i.e.. are the key presses and expected responses synchronized?) If the withdrawal amount exceeds the account balance, the user has no indication as to the error that has occurred. If the ATM cannot issue "a transaction record" at that particular time and requires a response in order to proceed or abort, the user is left to wonder what went wrong and where he or she is in the sequence. Long, silent pauses during transaction processing leave the customer guessing as to what went wrong. Operating the machine in this "open-loop mode" is similar to asking a blind person to drive a car from Point A to Point B based upon a list of performed instructions. In summary, an interactive machine cannot be operated by a set of rote instructions. Furthermore, it is pointless to provide the instructions in a code understood by perhaps only 7% to 14% of the target market.

Therefore, access to these terminals includes: 1) finding them, and, once they are found, 2) reading the printed information on the screens as well as 3) rapidly identifying the location and functions of the various controls; again, normally accomplished with labels.

We feel our prototype Talking Signs solution to accessing ATMs accomplishes the goals stated above: The first is to simply indicate the existence of and location of the teller machine. This function is provided by a moderately high output emitter above the ATM which is aimed in the approaching directions.

The second provides a spoken equivalent of the information appearing on the ATM display. This allows the transaction to occur in the "interactive mode" -- the mode in which the machine was designed to operate. This information is provided by a moderate output emitter which is received whenever the user approached the front of the ATM.

The third provides clear labeling of the physical features of the machine such as "card slot," "deposit slot," "receipt dispenser," and "cash >dispenser" -- features with which the visually-impaired customer must interact. Because infrared light transmission is highly directional, each component of the teller machine is labeled with a low output infrared emitter to identify that component. The customer "scans" the face of the teller machine with the receiver to locate the appropriate slot to accomplish that phase of the transaction.


This report was developed with assistance from The Smith-Kettlewell Eye Research Institute's Rehabilitation Engineering Research Center, the Federal Transit Administration, Project ACTION of the National Easter Seal Society, the National Institute on Disability and Rehabilitation Research and the City of San Francisco Department of Public Works.

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