Robert Wall Emerson

Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities

This report is intended to provide practitioners with useful information related to establishing safe crossings at roundabouts and channelized turn lanes for pedestrians with vision disabilities. The specific focus areas of the report provide guidance on: identifying under what conditions pedestrians with vision disabilities may experience problems with crossing performance; tying treatment solutions to specific crossing challenges faced by the visually impaired pedestrian population; conducting pedestrian/vehicle studies that help identify performance problems and appropriate treatment strategies; quantifying pedestrian accessibility at a particular crossing; presenting findings from selective field studies performed through this research; developing approaches for extending research findings to other locations; and discussing implications for the practitioner in terms of treatment selection and facility design. The results of this research will be useful to engineers, the accessibility community, policy makers, and the general public to aid in understanding the specific challenges experienced at these facilities by pedestrians with vision disabilities. It is only through the understanding of the components of the crossing task and the particular challenges involved that solutions can be developed, installed, and evaluated appropriately.

Increased Content Knowledge of Students with Visual Impairments as a Result of Extended Descriptions

The National Center for Accessible Media has developed a technology and protocol for inserting extended, enhanced descriptions of visually based concepts into artificially paused digital video. These “eDescriptions” describe material not fully explained by a narrator and provide analogies and explanation specifically designed for students who are visually impaired. In two experiments, fourth-grade students with visual impairments listened to video clips of narrated, age-appropriate curricular material with eDescriptions inserted along different organizational frameworks, as well as video with only standard narration. Students were first assessed on prior knowledge of the content to be covered in the videos. After three weeks, each student listened to the videos and answered questions assessing content acquired from the presentations. Students performed better on content tests for material that included eDescriptions than for material that only had standard narration. This effect was strongest when eDescriptions were placed prior to relevant material in a video. While the most effective strategy was using descriptions followed by the relevant video, both students and teachers preferred hearing a word first, followed by its definition. Other elements determined important to the creation of effective eDescriptions included selection of developmentally age appropriate vocabulary, length of individual eDescriptions, and overall length of a video when eDescriptions were added. The usefulness of eDescriptions for increasing acquisition of content information points to the need for further research into auditory description.

Impact of adding artificially generated alert sound to hybrid electric vehicles on their detectability by pedestrians who are blind

A repeated-measures design with block randomization was used for the study, in which 14 adults with visual impairments attempted to detect three different vehicles: a hybrid electric vehicle (HEV) with an artificially generated sound (Vehicle Sound for Pedestrians [VSP]), an HEV without the VSP, and a comparable internal combustion engine (ICE) vehicle. The VSP vehicle (mean +/- standard deviation [SD] = 38.3 +/- 14.8 m) was detected at a significantly farther distance than the HEV (mean +/- SD = 27.5 +/- 11.5 m), t = 4.823, p < 0.001, but no significant difference existed between the VSP and ICE vehicles (mean +/- SD = 34.5 +/- 14.3 m), t = 1.787, p = 0.10. Despite the overall sound level difference between the two test sites (parking lot = 48.7 dBA, roadway = 55.1 dBA), no significant difference in detection distance between the test sites was observed, F(1, 13) = 0.025, p = 0.88. No significant interaction was found between the vehicle type and test site, F(1.31, 16.98) = 0.272, p = 0.67. The findings of the study may help us understand how adding an artificially generated sound to an HEV could affect some of the orientation and mobility tasks performed by blind pedestrians.

Ergonomic Factors Related to Drop-Off Detection With the Long Cane: Effects of Cane Tips and Techniques

Objective: This study examined the effect of cane tips and cane techniques on drop-off detection with the long cane. Background: Blind pedestrians depend on a long cane to detect drop-offs. Missing a drop-off may result in falls or collision with moving vehicles in the street. Although cane tips appear to affect a cane user’s ability to detect drop-offs, few experimental studies have examined such effect. Method: A repeated-measures design with block randomization was used for the study. Participants were 17 adults who were legally blind and had no other disabilities. Participants attempted to detect the drop-offs of varied depths using different cane tips and cane techniques. Results: Drop-off detection rates were similar between the marshmallow tip (77.0%) and the marshmallow roller tip (79.4%) when both tips were used with the constant contact technique, p = .294. However, participants detected drop-offs at a significantly higher percentage when they used the constant contact technique with the marshmallow roller tip (79.4%) than when they used the two-point touch technique with the marshmallow tip (63.2%), p < .001. Conclusion: The constant contact technique used with a marshmallow roller tip (perceived as a less advantageous tip) was more effective than the two-point touch technique used with a marshmallow tip (perceived as a more advantageous tip) in detecting drop-offs. Application: The findings of the study may help cane users and orientation and mobility specialists select appropriate cane techniques and cane tips in accordance with the cane user’s characteristics and the nature of the travel environment.

Analysis of user characteristics related to drop-off detection with long cane.

This study examined how user characteristics affect drop-off detection with the long cane. A mixed-measures design with block randomization was used for the study, in which 32 visually impaired adults attempted to detect the drop-offs using different cane techniques. Younger cane users detected drop-offs significantly more reliably (mean +/- standard deviation = 74.2% +/- 11.2% of the time) than older cane users (60.9% +/- 10.8%), p = 0.009. The drop-off detection threshold of the younger participants (5.2 +/- 2.1 cm) was also statistically significantly smaller than that of the older participants (7.9 +/- 2.2 cm), p = 0.007. Those with early-onset visual impairment (78.0% +/- 9.0%) also detected drop-offs significantly more reliably than those with later-onset visual impairment (67.3% +/- 12.4%), p = 0.01. No interaction occurred between examined user characteristics (age and age at onset of visual impairment) and the type of cane technique used in drop-off detection. The findings of the study may help orientation and mobility specialists select appropriate cane techniques in accordance with the cane users age and onset of visual impairment.

Exploratory Analysis of Crossing Difficulties for Blind and Sighted Pedestrians at Channelized Turn Lanes

This paper presents the findings from a paired comparison study of blind and sighted pedestrians judging crossing opportunities in traffic from the roadside at three channelized turn lane (CTL) locations. It is motivated by the belief that the geometric nature of CTL facilities and the lack of signal control at the pedestrian crossing are factors that may negatively affect the delay and safety for blind pedestrians. Pedestrians waiting at the curb must judge the traffic moving in a circular motion, and they must deal with a significant amount of background traffic (i.e., noise) present at the main intersection. The findings show that crossings at all CTL crossing locations are significantly more difficult for blind pedestrians than for sighted pedestrians. Blind pedestrians tend to face a greater risk and a greater amount of delay. Furthermore, the research shows that conflicting traffic flow in the turn lane has a significant effect on crossing performance for both pedestrian groups; however, the effect of noise-generating background traffic on blind pedestrian crossings is not significant. The study also concludes that for this experiment the location of the crosswalk (in the center of the turn lane or at the downstream end) does not have a significant effect on crossing judgment performance.

Blind and Sighted Pedestrians’ Road-Crossing Judgments at a Single-Lane Roundabout

Objective: The aim of this study was to evaluate the relative risk and efficiency of road crossing experienced by blind and sighted pedestrians at a single-lane roundabout with two levels of traffic volume and at two distances from the roundabout. Background: With the rapid spread of modern roundabouts across the United States, their accessibility to blind pedestrians has become an important concern. To date, accessibility research relevant to blind pedestrians has focused on multilane roundabouts, and single-lane roundabouts have been virtually ignored. Method: Blind and sighted participants made judgments about when they would cross a single-lane roundabout with high and low traffic volumes, at exit and entry lanes, and at the actual crosswalks and at locations farther from the roundabout. Results: Relative to sighted participants, blind participants’ judgments about when to cross were more frequently risky, especially when traffic volume was high. Blind participants also were slower to make crossing judgments and accepted fewer crossing opportunities. Both groups made somewhat safer and more efficient judgments at locations farther from the roundabout. Conclusion: Some single-lane roundabouts may pose greater risk to blind pedestrians than to sighted pedestrians, especially when traffic volume is high. Crosswalk location merits further investigation as a design issue. Application: These findings are relevant to transportation planners and engineers who are responsible for the accessibility of public rights-of-way.

Vehicle surge detection and pathway discrimination by pedestrians who are blind: Effect of adding an alert sound to hybrid electric vehicles on performance

This study examined the effect of adding an artificially generated alert sound to a quiet vehicle on its detectability and localizability with 15 visually impaired adults. When starting from a stationary position, the hybrid electric vehicle with an alert sound was significantly more quickly and reliably detected than either the identical vehicle without such added sound or the comparable internal combustion engine vehicle. However, no significant difference was found between the vehicles in respect to how accurately the participants could discriminate the path of a given vehicle (straight vs. right turn). These results suggest that adding an artificial sound to a hybrid electric vehicle may help reduce delay in street crossing initiation by a blind pedestrian, but the benefit of such alert sound may not be obvious in determining whether the vehicle in his near parallel lane proceeds straight through the intersection or turns right in front of him.

Blind pedestrians and quieter vehicles: How adding artificial sounds impacts travel decisions

This research examined the influence “quiet” (e.g., hybrid and electric) vehicles may have on the ability of blind pedestrians to perform common orientation and mobility tasks under low vehicle speed conditions. The research involved blind participants detecting forward approaching vehicles and approaching backing vehicles, deciding whether a vehicle coming from behind or from the front but across an intersection would continue to go straight or turn across the intended path of travel of a pedestrian seeking to cross a street (i.e., a pathway discrimination task), and taking parallel and perpendicular alignment from passing traffic. Participants included some with normal hearing and some with impaired hearing.Testing was conducted on a public roadway and a parking lot in Kalamazoo, Michigan under ambient sound conditions consistent with a typical urban travel environment. Conditions involved evaluating internal combustion engine (ICE) Chevrolet Malibu and a set of hybrid Chevrolet Volts capable of operating in a “quiet” mode (referred to as Electric Mode or EM) or operating in EM but augmented with one of five different artificially-generated sounds emanating out of a front-bumper mounted speaker.All of the artificial sounds generally performed better against the baseline the Chevrolet Volt EM than the Chevrolet Malibu. This suggests that, to some extent, putting any one of these artificial sounds on a hybrid or electric vehicle may improve pedestrian performance on the measures examined relative to not adding any sound at all. One sound (sound 5) did not outperform against the Chevrolet Malibu in any measure and had the fewest instances of outperforming the Chevrolet Volt EM. Of the remaining 4 sounds, two sounds outperformed both the Chevrolet Malibu and the Chevrolet Volt EM on several measures. Against the Chevrolet Malibu, sound 2 was slightly better in detection distance and crossing margin while sound 4 was better in the path discrimination tasks. The two sounds were equivalent on the alignment tasks.The pathway discrimination task reflects one of the more potentially threatening situations in which a blind pedestrian might encounter a quiet vehicle (e.g., turning to cross the pedestrian’s path). Sound 4 performed much better than sound 2 on this measure, making it the most effective of all the artificial sounds examined. While these two sounds were equitable in the right-straight task, sound 4 showed almost half as many missed vehicle surges (i.e., forward movement from a stop) and 1/4 the rate of missed paths and incorrect judgments. Vehicle sound condition did not impact participants’ alignment. Normal hearing participants performed significantly better than hearing impaired participants on this task, but not as well as would be expected based on previous data [1].These results support the potential for artificially-generated sounds to improve the ability of blind pedestrians to detect approaching vehicles relative to what is being achieved with ICE vehicles. Regression analysis of the detection data supports previous results that sound energy in the 500 to 1000 Hz range is important for detection. However, the analysis indicates it is not that energy in this region that makes the signal more noticeable, but that energy in this region in the ambient environment hinders detection. Previous findings in low ambient conditions showing a predictive value for the amplitude modulation of an artificial sound were not supported in these data.Copyright

Drop-off detection with the long cane: effect of cane shaft weight and rigidity on performance

Abstract Most travellers who are blind rely on a long cane to detect drop-offs on their walking paths. We examined how different cane shaft materials affect drop-off detection performance through providing different vibrotactile and proprioceptive feedbacks to the cane user. Results of the study showed a significant interaction between cane shaft weight and how the cane is used. A heavier cane was advantageous for detecting drop-offs when the individual used the ‘constant contact technique’ – cane tip stays in contact with the walking surface at all times – but not when he used the ‘two-point touch technique’ – cane tip is rhythmically tapped on the surface. In addition, a more flexible cane was advantageous for detecting drop-offs when the two-point touch technique was used but not when the constant contact technique was used. It is recommended that, when blind individuals select a cane shaft material, they consider which long cane technique they use more often. Practitioner Summary: Long cane shaft material affects how well a blind individual can detect drop-offs. A heavier shaft was advantageous when using the constant contact technique (cane tip stays in continuous contact with the surface), while a more flexible shaft was better when using the two-point touch technique (cane tip rhythmically taps the surface).