Determining
Recommended Language
for Speech
Messages used by
Accessible Pedestrian Signals:
Final
Report
Accessible Design for
the Blind
Billie Louise Bentzen, Ph.D.,
Janet Barlow, M.Ed., and
Lukas Franck, M.Ed.
Research
supported in part by:
The Seeing
Eye
American
Council of the Blind
California
Council of the Blind
Center for
the Visually Impaired, Atlanta
U.S. Access
Board
January 7, 2002
Acknowledgement
The authors gratefully acknowledge the contribution of
Daniel Ashmead, Ph.D., Department of Hearing and Speech Sciences, Vanderbilt
University Medical Center, to sections on speech intelligibility in noise.
Accessible Pedestrian Signals (APS), to provide information to pedestrians who are blind, have been installed in some locations in the U.S. for over 30 years. Until recently, they have all been audible signals, with loudspeakers installed at the pedestrian signal head (ped head) that broadcast tones or messages across the intersection during the steady walk interval of the pedestrian crossing phase. The most commonly used signal, produced by several manufacturers, is one in which a repeating sound like “cuckoo” is used for crossings that run in a roughly north-south direction, and a repeating sound like “chirp” is used for crossings that run in a roughly east-west direction. A survey of orientation and mobility specialists conducted in 1998 by the Orientation and Mobility Division of the Association for Education and Rehabilitation of the Blind and Visually Impaired (Bentzen et al., 2000) and a parallel survey of pedestrians who are blind or visually impaired by the American Council of the Blind (Carroll & Bentzen, 1999) both indicated that this type of signal often provides ambiguous information.
Recently, APS that provide audible information from the pushbutton location have been introduced in the US. This type of signal has been used extensively in Europe and Australia for many years. It typically uses a rapidly repeating tone to indicate the walk interval, and a slower repeating tone during the “flashing don’t walk” and steady “don’t walk” intervals to indicate that the pedestrian should not initiate a crossing. This slowly repeating tone, or locator tone, alerts users to the need to press a button to request a walk signal, and helps users locate the pushbutton. Vibrotactile information is also provided in most of these signals. In the U.S., in some of these pushbutton integrated signals, speech messages are being used to indicate the walk interval information, as well as additional information when the pedestrian pushbutton is pushed during the “don’t walk” and “flashing don’t walk” intervals. A third type of APS provides a transmitted message, usually a speech message, from the pedestrian signal head to a receiver held by the traveler who is blind or visually impaired. This research focused on APS that provide directly audible speech messages, not transmitted messages.
At least five currently available accessible pedestrian signals in the U.S. offer the option of directly audible speech messages. APS manufactured by Polara Engineering, Inc., NOVAX Industries Corp., Prisma Teknik AB, Dick Campbell Co., and Bob Panich Consultancy Pty. Ltd. are all capable of having real time speech messages for the walk interval. All of these except the Panich signals are also capable of providing messages with additional information when the pedestrian pushbutton is pushed.
These speech signals are intended to be audible from 6-12 feet from the pushbutton pole, or to the building line, whichever is less, as stipulated in Guidance in the Manual on Uniform Traffic Control Devices (MUTCD 2000 4E.08). The speaker for these messages is located in the pushbutton unit, with the exception of the NOVAX signal, which also has a ped head mounted speaker. The signals are not intended to be heard from across the street. They are normally used in association with a quiet locator tone, repeating once a second, that informs approaching pedestrians that they need to push a button to request a pedestrian phase. This quiet tone also enables users to locate the pushbutton easily. In addition, a tactile arrow on the pushbutton unit is aligned in the direction of travel of the crosswalk to provide tactile indication of the crosswalk that is controlled by the pushbutton.
Signals having speech messages are seen by many blind pedestrians as being very user friendly, and able to provide unambiguous information about which street has the walk sign. They are capable of providing both real-time and fixed descriptive information. Real-time walk signal information can be provided about the status of the pedestrian signal. Pushbutton messages can potentially include the name of the intersection and the street actuated by the pushbutton, the geometry and/or signalization of the intersection, and nearby landmarks such as transit stops or public buildings. The pushbutton message on the Polara and Campbell are typically activated by pressing the button for three seconds or more; the Prisma message is activated immediately when the button is pushed. The NOVAX signal has the capability of providing pushbutton messages, but it has not yet been used in this fashion.
During the deliberations of the Public Rights-of-Way Access Advisory Committee (PROWAAC) (Access Board, 2001), representatives of the National Federation of the Blind, the American Council of the Blind, the Council of Citizens with Low Vision, the Association for Education and Rehabilitation of the Blind and Visually Impaired, and The Seeing Eye all supported the use of APS having speech messages to reduce possible ambiguity about which crosswalk has the walk signal at some intersections. PROWAAC was established by the U.S. Access Board in 1999 to provide recommendations for minimum guidelines and requirements for implementing the Americans with Disabilities Act in public-rights-of-way.
There currently is minimal standardization of either walk messages or pushbutton messages for APSs, however, therefore message content, length, and structure vary from one APS installation to another. The only existing standard for the wording of APS speech messages is contained in The Millennium Edition of the Manual on Uniform Traffic Control Devices (MUTCD 2000 4E.06). This standard requires that where verbal messages are provided during the walk interval, “the verbal message . . . shall be the term ‘walk sign,’ which may be followed by the name of the street to be crossed,” and the “verbal message . . . when the walk interval is not timing . . . shall be the term ‘wait.’” As an option “Accessible pedestrian signals that provide verbal messages may provide similar messages in languages other than English, if needed, except for the terms “walk sign” and “wait.” The specification of the terms “walk sign” and “wait” was based on research conducted for The Smith-Kettlewell Eye Research Institute (Myers, Bentzen & Crandall, 1996).
This research on speech messages for APS was undertaken to develop recommendations based on data from stakeholders to form the basis for the establishment of recommended practice for the structure and content of walk messages and pushbutton messages for directly audible accessible pedestrian signals.
Other concerns regarding speech messages for APS, in addition to standardization of message content and structure, include the following.
Research on intelligibility of speech in noise is also
relevant to the general consideration of the use of speech messages in
APS. A number of speech-in-noise tests have been used by audiologists and
hearing scientists. In most of these tests the information is sound from
loudspeakers. Typically the background
noise on these tests consists of pre-recorded conversational babble from
multiple speakers (like “cocktail party” noise). The listener’s task is to
listen to speech samples and report the word or sentence which was spoken. The
measure is percentage of utterances reported correctly. The test is usually
done at several different signal-to-noise ratios.
A recent report by
Killion (1999) provides an example of the findings. Listeners with normal
hearing required a signal-to-noise ratio of +2 dB to get 50% of sentences
correct, and +5 dB to get 90% correct. Listeners with hearing impairments
required signal-to-noise ratios of +8 dB for 50% correct and +15 dB for 90%
correct. These findings suggest that a signal-to-noise ratio of +5 dB or more
is required for good speech intelligibility by persons with normal hearing, in
listening situations where the listener is not able to see the speaker. However a large majority of persons with
visual impairments are over the age of 60 and thus can be expected to have
age-related hearing loss, particularly for higher frequencies. Thus, speech messages in APS may need to be
equal to or greater than 15 dBA above ambient traffic sound to be intelligible
to many persons with visual impairments.
Speech-in-noise tests of
the sort represented by the Killion (1999) study have some limitations in terms
of generalization to audible pedestrian signals. One is that the background
noise was conversational babble, which has the same spectral composition as the
speech signals. However, traffic sound has most of the energy concentrated in
the lower frequencies (Wiener et al., 1997).
Persons with visual impairments who have normal hearing may be able to
understand APS speech messages better in the context of ambient traffic sound
than conversational babble because of the difference in spectral
composition. However, the majority of
persons with visual impairments who are likely to have age-related hearing loss
can be expected to have more difficulty hearing the higher frequencies in
speech than the predominantly lower frequencies in traffic noise. Therefore the
results of tests such as that of Killion (1999) may underestimate the amount by
which APS speech messages need to exceed the intensity of traffic noise in
order to be intelligible to older blind pedestrians.
It may not be possible
to provide APS with intelligible speech messages that are not so loud as to
have the potential for causing hearing loss.
The MUTCD says that the maximum volume of APS should be 89 dB, and APS
should be no more than 5 dB louder than ambient sound (4E.06). The 89 dB upper
absolute limit was set by the Federal Highway Administration to comply with
OSHA standards. The 5 dB upper limit
relative to ambient sound was based on research that found that an 880 Hz
square wave tone used as an APS locator tone was more readily perceived and
localized by blind persons from distances of up to twelve feet when it was 2-5
dB above ambient vehicular sound along an eight lane artery than when it was 10
dB above that ambient sound Bentzen et al, 2000).
Another limitation in
generalizing to APS the results of Killion (1999) and related research is that
the background noise levels tend not to be as high as in traffic
situations. Mean traffic noise for
traffic accelerating at the onset of 20 walk intervals on a four-lane street
was measured at 94 dBA from the position at which a pedestrian who is visually
impaired would be standing while waiting to cross the street (Wiener et al.,
1997). The microphone of an APS which
senses ambient sound level may be located up to 12 feet, (or sometimes more),
from the position of pedestrians waiting to cross, and hence measure a lower
sound level. It may then control a
signal output which is, for example, 5 dB louder than the ambient sound at the
APS, but this sound, measured from the position of the person waiting to cross
the street, may not even be as loud as the vehicular noise heard from that
position. In order to make the speech
loud enough to be intelligible by a pedestrian waiting to cross, it might have
to be objectionably loud when heard by a person standing close to the APS.
This research does not address the above issues, which should be considered in any installation of APS using speech messages. This research only provides recommendations regarding the structure and content of walk messages and pushbutton messages, when speech messages are used on APS.
An Expert Panel met by teleconference to develop a survey to be given to stakeholders, including pedestrians who are visually impaired, orientation and mobility specialists, transportation engineers, and accessible pedestrian signal manufacturers. The Expert Panel was comprised of the three co-principal investigators (authors, all Certified Orientation and Mobility Specialists), and one representative familiar with speech equipped APSs from each of the following groups: transportation engineers, APS manufacturers, Council of Citizens with Low Vision, and the American Council of the Blind.[1] The National Federation of the Blind declined the invitation to participate in this research.
The Expert Panel developed sample walk interval and pushbutton messages that were applicable to different intersection geometries and signalization patterns, and that varied in message content, length, and structure. Each message approved by the Expert Panel was required to have consensus that it could be appropriate in content and structure. Appropriate messages were those that were judged by most Expert Panel members to be unambiguous, and to clearly convey the minimum necessary information.
The Expert Panel discussed several issues of message content and wording extensively and made the following recommendations:
Therefore these wordings and types of information were not included in the sample messages developed by the Expert Panel. (For explanation of the rationale for these recommendations, see Results and Discussion.)
In this order, the information necessary to the greatest number of users comes first.
Messages selected by the Expert Panel were developed into a survey instrument for obtaining data on preference for message types by blind pedestrians, orientation and mobility specialists, transportation engineers, and APS manufacturers. The survey also contained items to evaluate the understanding of various message types, and preferences for use of the pushbutton delay to actuate pushbutton messages.
The survey was mailed to160 people who are actively involved in decision-making about pedestrian signals or in teaching pedestrians with visual impairments to recognize and interpret the geometric and signal information at intersections; these people represented the following categories of stake-holders: orientation and mobility specialists, APS manufacturers and distributors, and transportation engineers. The same survey was administered in Braille, large print, or orally to 170 pedestrians with visual impairments who were attending the convention of the American Council of the Blind during the first week of July 2001.
Of the 170 respondents with visual impairments, 84.2% were usually unable to read street signs, see traffic lights and see Walk/Don’t Walk signs, and 15.8% were usually able to read street signs, see traffic lights and see Walk/Don’t Walk signs. Respondents were asked to indicate the frequency with which they independently crossed streets with traffic lights; 72.5% reported that they independently crossed streets with traffic lights at least once a week, while 27.5% reported that they independently crossed streets with traffic lights less often or never. Ages of respondents were: <40=23.5%; 40—54=50.0%; 55—69=21.8%; >69=8.8%. Respondents were not systematically asked to indicate what travel aid, (such as a long cane, dog guide, optical aid, or no aid) they typically use, however, 89 respondents were observed to be using a long cane and 62 were observed to be using a dog guide in traveling to the survey area.
The panel reviewed the survey results via a conference call and made recommendations based on the results and comments.
Expert Panel members had extensive discussion of safety concerns related to the wording of the walk and pushbutton messages. It was considered essential that the walk message be worded as “Walk sign” or “Walk sign is on.” This is consistent with the MUTCD. The wording indicates the status of the signal; it does not give a command or imply that it is safe to cross.
There was concern that some messages that have been used on pushbutton messages, such as “Crossing Charles at State,” could be misinterpreted as a walk message by a pedestrian unfamiliar with such messages. This discussion led to the decision that the words, “crossing” and “walk sign” should not be included in the pushbutton messages. There was also discussion of the words “to cross.” The panel decided that “to cross” could be used as part of a phrase in the pushbutton message, but not at the beginning of the message. If used at the beginning of a message, if the word “to” is not heard or understood, pedestrians could mistakenly understand that “cross” means they should cross now.
The Expert Panel also decided that the word “wait” should be included in every pushbutton message, because pushbutton messages always come on during either the flashing or steady don’t walk intervals. This is consistent with the requirements of the MUTCD.
The Expert Panel discussed the types of information to be provided by the messages at length. While there was recognition that APS could provide landmark and construction information, the panel decided that APS should only be used to provide crossing and intersection information. That is, the APS should be a pedestrian signal only. The separation of traffic signal information from other types of information was considered a safety issue. The panel felt that other types of information should be provided by other means. Providing landmark or construction information was considered analogous to adding signs to the pedestrian signal head. In addition, the realities of maintenance, typical departmental structure of public works departments, and the necessity of deciding on a case by case basis what messages were included and how they should be worded were determined to be problematic. Therefore, the sample messages on the survey did not include this type of information.
The panel also discussed the fact that different messages might be understood differently by different stakeholders. In particular, the traffic engineering representative pointed out that a message such as “Howard Street, Walk Sign” would typically be understood in the traffic engineering community to indicate that the walk signal was on to make a crossing parallel to Howard Street, while that message is currently being used on APS to indicate that the walk signal is on to cross Howard Street. This led to the inclusion of questions to determine the understanding of messages by the various groups.
Surveys were completed by 170 pedestrians who were legally blind. The response rate for the 160 surveys mailed to the other stakeholders was 37.5%, comprised of 26 Orientation and Mobility Specialists, 29 Transportation Engineers, and 5 APS manufacturers or distributors.
In eight items designed to determine respondents’ subjective evaluation to walk interval and pushbutton messages, respondents were asked to rate sample messages on a three point scale in terms of whether they were “good” messages, that is, messages they thought had the necessary information and that would be understood correctly. (1=poor; 3=good) The number of sample messages for each of these eight items, representing three situations in which walk messages were used and five situations in which pushbutton messages were used, ranged from two to eight. For these questions in which the response was a rating, means were computed for each sample message by groups, blind (totally blind and low vision), orientation and mobility (O & M) specialists, and transportation engineers, for the three large groups. Selected planned comparisons were then performed for the three items having six or eight sample messages, to determine whether observed differences in mean ratings between the highest rated sample message in each group and other messages in that group were significant; that is, whether there was less than .05 probability that the observed differences were attributable to chance. (Seven planned comparisons were performed for each of two items and five were performed for one item.)
In five items, respondents were asked to mark a choice that indicated their understanding of walk interval or pushbutton messages. There were three choices, a choice that the authors are calling the correct choice (that is, the way speech messages have typically been configured on APS), an incorrect choice, and “I’m not sure.” Frequencies were computed, by major respondent group, for each of these questions.
Respondents were also asked whether they thought it was best to have the pushbutton message come on only after the button is pushed for a minimum number of seconds. Responses were “Yes,” “No,” or “No opinion.” Frequencies were computed by major group, and Chi Square tests performed.
Respondents were given the opportunity to indicate particular wordings they thought were good or did not think were good, and to suggest alternative wordings.
Following statistical analysis, the Expert Panel convened by teleconference to interpret the results, combining the results for preference with those for accurate understanding of the message, respondents’ additional suggestions, and their own expertise.
In each of the first two questions, respondents were asked to rate each of eight sample messages intended to convey that the walk sign was on to cross the street in front of them (the perpendicular street). In the first question, respondents were to rate sample messages for their use at a crossing where it would be obvious from the location of the pushbutton, or the nature of the intersection, such as a mid-block crossing, which crosswalk would have the walk signal when a walk message was heard. In the second question, respondents were asked to rate the same eight sample messages for use at a corner where it might not be obvious which of two crosswalks had the walk signal when a walk signal came on, such as when there are two pushbuttons mounted on the same pole, serving two different crosswalks. Mean responses of those participants who rated all eight messages in each group can be seen in Table 1.
Table 1. Mean ratings of sample walk signal messages for locations where it would be obvious which crosswalk had the walk interval and for locations where it would not be obvious which crosswalk had the walk interval The highest mean rating for each situation, for each respondent group, is indicated by an asterisk. Means in bold type did not differ significantly from the highest mean for that situation and group.
|
Sample Walk Messages |
Blind |
O&M Specialists |
Engineers |
|
|
Mean |
Mean |
Mean |
|
At a signal where
it is obvious which crosswalk has the walk signal. |
N=135 |
N=26 |
N=25 |
|
Walk sign. |
1.70 |
1.65 |
1.44 |
|
Walk sign is on. |
1.99 |
1.73 |
1.68 |
|
Howard Street, Walk sign. |
2.33* |
2.35 |
1.64 |
|
Walk sign is on to cross Howard Street. |
2.24 |
2.12 |
2.52* |
|
Howard Street, Walk sign is on. |
2.29 |
2.39* |
2.08 |
|
Walk sign, Howard Street. |
2.13 |
2.19 |
1.96 |
|
Walk sign on, Howard Street. |
2.14 |
2.15 |
1.92 |
|
Howard Street, Walk sign on. |
2.25 |
2.35 |
1.96 |
|
|
|
|
|
|
At a signal where
it is not obvious which crosswalk has the walk signal. |
N=131 |
N=24 |
N=24 |
|
Walk sign. |
1.18 |
1.13 |
1.21 |
|
Walk sign is on. |
1.35 |
1.08 |
1.25 |
|
Howard Street, Walk sign. |
2.25 |
2.42* |
1.71 |
|
Walk sign is on to cross Howard Street. |
2.44 |
2.13 |
2.58* |
|
Howard Street, Walk sign is on. |
2.47* |
2.29 |
1.96 |
|
Walk sign, Howard Street. |
2.12 |
2.00 |
1.83 |
|
Walk sign on, Howard Street. |
2.22 |
2.13 |
1.83 |
|
Howard Street, Walk sign on. |
2.44 |
2.38 |
1.88 |
For both types of intersections, respondents in all groups rated walk messages that included the name of the street to be crossed higher than messages that did not include the street name. There was a tendency across blind respondents and orientation and mobility specialists to rate messages beginning with the street name higher than messages beginning with “Walk sign,” although most differences were not statistically significant. Traffic engineers rated the message that was the most complete grammatical sentence significantly higher than all other messages.
Regardless of preferences for message types, it is essential that walk signal messages correctly convey to users which crosswalk has the walk signal. APS are required by the MUTCD (4E.06) and the recommendations of PROWAAC (X02.5.2.2A) to provide unambiguous information about which crosswalk has the walk interval. Respondents were therefore asked two questions to determine the relative importance to understanding the walk signal message, of complete phrasing versus more concise phrasing. Frequency of responses to each question can be seen in Table 2.
Table 2. Understanding of sample walk interval messages. Number of respondents in each group who provided each response. The meaning the APS message would be intended to convey to pedestrians (the correct response) is indicated in bold print.
|
Sample Messages, and Responses |
Blind |
O & M Specialist |
Engineer |
|
|
|
|
|
|
Mess: “Walk sign is on to cross Howard St.” |
|
|
|
|
Resp. A. Howard St. is the street parallel to the crossing. |
5 |
0 |
0 |
|
Resp. B.
Howard St. is the street to be crossed. |
155 |
26 |
29 |
|
Resp. C. I'm not sure. |
7 |
0 |
0 |
|
|
|
|
|
|
Mess: “Howard St. Walk sign.” |
|
|
|
|
Resp. A. Howard St. is the street parallel to the crossing. |
9 |
0 |
2 |
|
Resp. B.
Howard St. is the street to be crossed. |
135 |
23 |
17 |
|
Resp. C. I'm not sure. |
23 |
3 |
10 |
For the walk message “Walk sign is on to cross Howard St., 92.8% of blind respondents correctly understood that Howard St. was the street to be crossed. For the walk message “Howard St. Walk sign,” only 80.8% of blind respondents correctly understood the message to mean that Howard St. was the street to be crossed, that is, the street for which the walk sign now says WALK.
Twelve respondents spread across all groups stated that more concise messages are better, however one blind respondent stated that the best messages were “more phrase like.” This expressed preference for more concise messages does not correspond with the preference ratings or the data on understanding messages, however.
In considering the walk interval messages, the Expert Panel recognized that despite comments to the contrary, participants not only rated the more completely phrased messages more highly than the more concise messages, but were also more likely to understand the more completely phrased messages correctly. However, Expert Panel members were concerned that 7.2% of blind respondents interpreted the most accurately interpreted message incorrectly or found it ambiguous.
Another reason Expert Panel members preferred the more fully phrased walk signal message was that it was consistently interpreted by traffic engineers in the same way as it was intended to be interpreted by pedestrians who are visually impaired. Having this agreement in interpretation will facilitate correct installation of APS having speech messages.
Additionally, Panel members were strongly of the opinion that the street name should come first in the message. This is because users are primed to hear “Walk sign,” and may incorrectly assume that the street they desire to cross is the one that has the walk sign, and begin their crossing without waiting to be sure which street is being signaled. Users who are familiar with speech signals at a particular intersection will not be delayed in their crossing by having the name of the street first, and users who are unfamiliar with speech signals at a particular intersection, or who are careless at a particular time, will have the information first that is critical to life safety. This is consistent with the high ratings given by blind respondents and orientation and mobility specialists to sample messages in which the street name comes first.
Therefore Panel members concluded that the recommended wording for walk messages should follow the model “Howard. Walk sign is on to cross Howard.” They recommended that the designations “Street,” “Avenue,” etc. should not be used unless necessary to distinguish between roadway names that are similar in a particular geographic area.
Respondents were asked to rate six sample pushbutton messages which could be available from a speaker at the pushbutton during the don’t walk and flashing don’t walk intervals. The messages were intended to identify the intersection and to identify the particular street whose walk signal would be actuated by the pushbutton. PROWAAC recommends requiring (X02.5.1.4 A) that unambiguous information be provided at pushbuttons indicating which walk signal is requested by that pushbutton. The MUTCD says that unambiguous information should be provided (MUTCD 4E.08). PROWAAC (X02.5.1.4 C) also recommends requiring intersection identification information at each APS. Mean ratings of those participants who rated each of the six sample messages in this item are presented in Table 3.
Table 3. Mean ratings of sample pushbutton messages providing intersection identification. The highest mean rating for each group is indicated by an asterisk. Means in bold type were not significantly different from the highest mean for that group.
|
Sample Pushbutton messages Providing Intersection Identification |
Blind N=118 |
O&M Specialists N=26 |
Engineers N=25 |
|
Mean |
Mean |
Mean |
|
|
Pushbutton for Howard St. at Grand Ave. Wait. |
1.98 |
2.08 |
1.72 |
|
Requesting Howard St. at Grand Ave. Wait. |
1.92 |
1.62 |
1.40 |
|
Request for Howard St. at Grand Ave. Wait. |
1.97 |
1.81 |
1.48 |
|
Request to cross Howard St. at Grand Ave. Wait. |
2.44 |
2.23 |
2.20 |
|
Wait to cross Howard St. at Grand Ave. |
2.54* |
2.54* |
2.28 |
|
Requesting to cross Howard St. at Grand Ave. Wait. |
2.14 |
2.00 |
2.36* |
Both blind respondents and orientation and mobility specialists rated the message “Wait to cross Howard St. at Grand Ave.” the highest, but not significantly higher than “Request to cross Howard St. at Grand Ave. Wait.” Most messages that began with “Request” or “Requesting,” or that did not contain the words “to cross,” were rated lower. Traffic engineers again rated most highly the message that was the most grammatically complete, but this was not significantly different from the ratings of the two messages most highly rated by blind respondents and orientation and mobility specialists.
Respondents were also asked to respond to three items to determine their understanding of the intersection identification messages. Regardless of preference for a particular wording, if many people misunderstand the wording or are unclear about its meaning, it is not a good message. Frequency of response to each item is shown in Table 4.
For the message “Wait to cross Joy St. at Central Ave.” 82.8% (135) of blind respondents correctly understood the message to mean they had pushed the button to cross Joy St. For the message “Requesting Central Ave. at Joy St. Wait.” 70.6% (120) of blind respondents correctly understood the message to mean that they had pushed the button (put in a request to the signal controller), to cross Central Ave. For the street identification message “Pushbutton for Joy St. at Central Ave. Wait.” Only 70.4% (119) of blind respondents correctly understood the message to mean that they had pushed the button to cross Joy St.
Table 4. Understanding of sample pushbutton messages providing intersection identification. Number of respondents in each group who provided each response. The response designated as correct is indicated in bold print.
|
Sample messages,
and responses |
Blind |
O & M Specialist |
Engineer |
|
|
|
|
|
|
Mess: “Wait to cross Joy St. at Central Ave.” |
|
|
|
|
Resp. A. You have pushed the button to cross Central Ave. |
14 |
0 |
1 |
|
Resp. B. You have pushed the button to cross Joy
St. |
135 |
26 |
27 |
|
Resp. C. You don't know. |
14 |
0 |
1 |
|
|
|
|
|
|
Mess: “Requesting
Central Ave. at Joy St. Wait.” |
|