National Institute on Disability and Rehabilitation Research

Remote Infrared Signage Developmen to Address Current and Emerging Access Problems for Blind Individuals

Part I

Smith-Kettlewell Research on the Use of Talking Signs®
at Light Controlled Street Crossings

METHODS

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.

Subjects

Participants were recruited by word of mouth through agencies and service providers in the blindness system and through referrals by friends and colleagues who are also blind. Participants had to be independent travelers who were visually impaired and unable to see pedestrian signals or painted crosswalk lines, or to visually identify the curb line. They ranged in age from 21 to 62. There were 15 males and 5 females. Most participants considered themselves to be good to excellent travelers. Two participants considered themselves to be fair to poor travelers but did travel some familiar outdoor routes independently. Two participants used dog guides as their preferred travel aid, and 18 traveled with a long cane. Four of the 20 participants had mild to moderate hearing loss; one of these used a dog guide.

Materials

The experiment took place at one crosswalk at each of four intersections in San Francisco's Civic Center area. Three of the intersections were plus-shaped (four-way), and one was T-shaped (3-way). All four of the intersections had fixed timed traffic lights. (See Figure 3.)

Figure 3. Twenty-nine Talking Signs units were installed atop pedestrian crossing signals in the Civic Center area of San Francisco.

One plus-shaped intersection (at Grove and Larkin Streets), was 89 feet wide, and characterized by variable amounts of traffic, much of which turned. The curb ramp was not well aligned with the direction of the crosswalk. The crosswalk was straight ahead (10 degrees deviation). The auxiliary message was: "This is a plus shaped intersection. It is controlled by a fixed timed traffic light in which the walk phase begins with the onset of traffic on Grove. Larkin has two-way traffic on this side of Grove, but one-way traffic coming toward you on the opposite side of Grove. The San Francisco Public Library is across Larkin, and has entrances on both Larkin and Grove."

Another plus-shaped intersection (at Grove and Polk streets), was 79 feet wide, and the crosswalk involved in the experiment angled to the right, 10 degrees away from the center of the intersection, as the parallel street widened beyond the center of the intersection. The curb ramp was not well aligned with the direction of the crosswalk. The auxiliary message was: "This is a plus shaped intersection. It is controlled by a fixed timed traffic light in which the walk phase begins with the onset of traffic on Polk. Polk is one way coming towards you. The crosswalk is angled away from Polk. Grove is 6 lanes wide."

The third plus-shaped intersection (at Market and Hyde streets), had a boarding platform in the street that the participant was facing. Participants were asked just to get to this platform, which was immediately to the left of the crosswalk, and beyond the first lane of traffic perpendicular to their direction of travel. The curb ramp was well aligned with the direction of the crosswalk, but to locate the boarding platform, participants had to be searching well to the left of straight ahead as they crossed the street. The auxiliary message was: "This is an irregular intersection. Hyde ends at Market, intersecting it from the left. On the other side of Market, 8th begins, perpendicular to Market. This intersection is controlled by a fixed timed traffic light in which the walk phase begins with the onset of traffic on Hyde. Hyde is one way with traffic going in the direction you are facing. Market is four lanes wide. On this corner, to your left, is a Muni/BART entrance with steps going down parallel to Market. There is a boarding platform in Market between the 1st and 2nd lanes, for the Muni F, 6, 7, 9, 66, 71 and L and N buses. The boarding platform begins along the side of the crosswalk farthest from the intersection. There is a curbside bus stop for the Muni 21 just to your left, on Market."

At the T-shaped intersection (at Hyde and Fulton Streets) participants crossed from the top of the T to the stem of the T, at a marked crosswalk. The top of the T was 53 feet wide, and restricted to one-way vehicular traffic coming from the participant's right. There was little traffic on the stem of the T, and the curb ramp was not well aligned with the direction of the crosswalk. The crosswalk was angled 20 degrees away from the intersection. The auxiliary message was: "This is a T-shaped intersecton. You are at the top of the T facing the stem. This intersection is controlled by a fixed timed traffic light in which the walk phase begins with the onset of traffic on Fulton. Hyde is one way with traffic coming from your right. The crosswalk is angled away from Fulton. The San Francisco Public Library is across Hyde and has a mid block entrance on Fulton. A buzzer at the library indicates that cars are exiting the library parking lot, onto Hyde."

Although some participants had previously traveled in the area of the experiment, care was taken to provide minimal opportunity for participants to become aware just which intersections they were crossing. They were guided from one intersection to the next by circuitous routes.

In order to access the additional messages, a talking signs receiver was modified so that participants could select the functional equivalent of a "second channel" of information. The Auxiliary Message was stored in a palm-sized unit which participants carried on a waist strap. If such a second channel were to be implemented by Talking Signs, that information would be transmitted from the same source (on ped heads) as the conventional messages. Alternatively, this auxiliary message could be stored and transmitted along with the more specific orientation message previously described (direction of travel, block number, etc.)
A protocol and data sheets were the only additional materials. (See Appendix.)

Procedure

Participants completed the experiment individually, in sessions lasting approximately 90 minutes. Before completing the experimental procedure, participants received approximately 10 minutes of training in using Talking Signs at a crosswalk that was not subsequently used in the experiment. During the training, participants practiced obtaining information from both the primary and secondary channels as they crossed at the practice crosswalk at least two times. All procedures were completed between 9:00 am and 8:00 PM under prevailing vehicular and pedestrian conditions.

Three experimenters were with participants at all times. L. Myers provided all guidance, assistance and instruction to participants, and was the orientation and mobility specialist most responsible for participant safety. B. Bentzen recorded all data. W. Crandall provided technical support to assure consistency and reliability of the systems employed.

During the experiment, participants were guided by an experimenter to a starting location 25 to 50 feet from the street to be crossed. For both Talking Sign and no Talking Sign conditions, for the two plus-shaped intersections, the only instruction participants received from the experimenter was "Cross the street that's in front of you." For the T intersection, participants were instructed to "Find a mid-block crossing and cross the street on your right." For the fourth intersection, for both Talking Sign and no Talking Sign conditions, participants were asked to "Go to the boarding platform that is in the street in front of you."

During the experiment, in the Talking Signs conditions, participants were required to always listen for identifying information as they approached the intersection. When they reached the intersection and decided that they were well positioned at the crosswalk, they switched to the secondary channel and listened to the Auxiliary message, finally they switched back to the primary channel and kept the on button depressed until they received a message saying "Walk sign, (name) Street." They then listened for traffic to be sure the way was clear, and initiated their crossing. Participants were asked to not use their Talking Signs receiver while they were in the street.

After each crossing in both conditions, participants were asked what information they used to determine their heading, what information they used to determine when it was safe to cross, what the shape of the intersection was, and what the traffic control system was at that intersection. They were given no feedback regarding their crossing. They were guided immediately, by a circuitous route, to the next crosswalk.

Participants were divided into two groups, balanced as nearly as possible for reported travel ability, additional disability, and use of a cane vs. a dog guide for travel. The order of the trials was counterbalanced to minimize practice effects; one group completed crossings of two intersections with Talking Signs first and then crossings of the other two intersections without Talking Signs. Then the two crossings which had been completed using Talking Signs were completed without Talking Signs and the two crossings which had been completed with Talking Signs were completed without Talking Signs. The other group completed crossings in the reverse sequence. Participants were asked to make each crossing as if no experimenters were present who would assure their safety. That is, if, after arriving at a crossing and considering the information available, they determined that they would normally request assistance for that particular unfamiliar crossing, they were to request assistance. In the interest of reducing stress and fatigue on participants, they were asked to request assistance from an experimenter rather than a passerby. They could request assistance with any aspect of the crossing, such as finding the crosswalk, aligning to face the destination curb, identifying the onset of the walk interval, or being guided across the street. The experimenter did not offer assistance in locating the crosswalk or initiating the crossing. However, participants were assured that an experimenter would intervene during a crossing if there was risk of injury.

During each street crossing the following types of data were collected by an experimenter. Numbered items were subsequently subjected to statistical analysis. Other items were used for descriptive analysis (See Appendix).

Safety

1. During what part of the signal cycle did the participant start the crossing?
Under what traffic condition/s did the participant start the crossing?

Precision

2. Where did the participant begin the crossing, relative to the cross walk and curb ramp?

3. In what direction was the participant aligned when he/she began the crossing, relative to the crosswalk and the parallel street?

4. Where did the participant end the crossing, relative to the cross walk and the desired corner?

Independence

5. Did the participant request assistance to find the crosswalk?

6. Did the participant request that the experimenter tell him/her when it was safe to begin crossing, or did the experimenter provide this information after the participant had failed to initiate a crossing during three successive walk intervals?

7. Did the participant request assistance crossing the street, or did the experimenter intervene to prevent possible injury?

After each crossing participants were asked the following questions:

8. What information did you use to align yourself before you crossed the street?

9. How did you know when it was safe to cross the street?

10. What shape do you think the intersection was?

11. What kind of traffic control do you think the intersection had?

12. What other information did you find useful or necessary in planning this crossing?

After completing all crossings, subjective data were obtained from particpants regarding their evaluation of the usefulness of different features of the system. (See Appendix)