Blind Pedestrians Research Articles

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.

EmoSense: An Ambulatory Device for the Assessment of ANS Activity—Application in the Objective Evaluation of Stress With the Blind

Analysis of autonomic nervous system activity is a subject of increasing interest in the fields of health care and handicap management, as it provides information on the emotional, sensorial, and cognitive states of the patient. In this context, the simultaneous measurement of several physiological signals using small, discreet, mobile devices is required, in order to unobtrusively obtain such information under real-life conditions. We have therefore developed an ambulatory device which enables the measurement of heart rate, electrodermal activity, and skin temperature with noninvasive sensors. Wireless communication and local data storage on a memory card enables the device to be used during in-situ experiments for the analysis of autonomic nervous system activity. We have used this instrumentation in a study for the objective evaluation of stress in the blind when walking in urban space, through the analysis of electrodermal activity of blind pedestrians who independently followed a charted course involving a range of urban conditions. Experimenting in real-life settings has lead to the definition of novel, more pertinent parameters for the analysis of physiological signals in the study of autonomic nervous system activity. Results from these experiments have identified, for the first time, some rather surprising obstacles or events which give rise to an increased stress for the blind. These results were very encouraging for the use of such ambulatory devices for experiments under real- life conditions.

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.

탑-뷰 변환과 빔-레이 모델을 이용한 영상기반 보행 안내 시스템

본 논문은 야외 환경에서 하나의 카메라를 이용한 시각 장애인을 위한 보행 안내 시스템을 제안한다. 기존의 스테레오 비전을 이용한 보행 지원 시스템과는 다르게 제안된 시스템은 사용자의 허리에 고정된 하나의 카메라를 이용하여 꼭 필요한 정보만을 얻는 것을 목표로 하는 시스템이다. 제안하는 시스템은 먼저 탑-뷰 영상을 생성하고, 생성된 탑-뷰 영상 내 지역적인 코너 극점을 검출한다. 검출된 극점에서 방사형의 히스토그램을 분석하여 장애물을 검출한다. 그리고 사용자 움직임은 사용자에 가까운 지역 안에서 옵티컬 플로우를 사용하여 추정한다. 이렇게 영상으로부터 추출된 정보들을 기반으로 음성 메시지 생성 모듈은 보행 지시 정보를 합성된 음성을 통해 시각 장애인에게 전달한다. 다양한실험 영상들을 사용하여 제안한 보행 안내 시스템이 일반 인도에서 유용한 안내 지시를 제공하는 것이 가능함을 보인다. This paper presents a walking guidance system for blind pedestrians in an outdoor environment using just one single camera. Unlike many existing travel-aid systems that rely on stereo-vision, the proposed system aims to get necessary information of the road environment by using just single camera fixed at the belly of the user. To achieve this goal, a top-view image of the road is used, on which obstacles are detected by first extracting local extreme points and then verified by the polar edge histogram. Meanwhile, user motion is estimated by using optical flow in an area close to the user. Based on these information extracted from image domain, an audio message generation scheme is proposed to deliver guidance instructions via synthetic voice to the blind user. Experiments with several sidewalk video-clips show that the proposed walking guidance system is able to provide useful guidance instructions under certain sidewalk environments.

The Effectiveness of Facility Assembly Devices Concerning the Wayfinding of People with Visual Impairments

The study of more effective methods in terms of environmental cognition to assist visually impaired people in moving about in a space is the primary objective concerning the accessibility of disabled people. Mobility aids supplemented by hearing and echo-location cues have proven to be the most difficult concerning the improvement of mobility in finding a safe path through the immediate environment. How to develop facilities without auditory aids and carriers and to overcome the functional limitation of a single component for blind pedestrians is a necessary issue. A school with continuous space and a simple route and an office composed of open space and a complex route were selected as examples. The procedure of the experiment consisted of four phases; first, wayfinding was processed to evaluate the original environment; second, a tactile map was located at the start of the route; third, handrails were added along the test route, and finally, door signs were placed on doors. Fifteen visually impaired persons were selected for each phase. The results showed that both the tactile map and handrails with Braille landmarks were more effective in regard to wayfinding than were door signs. Handrails and door signs improved upon the limitations of a tactile map, raised the accuracy ratio of wayfinding close to 100%, and were more effective in a complex environment than in a simple environment.

Universal technologies in ICT

This special issue collects the extended and revised versions of the best papers that were presented at the International Conference on Universal Technologies—Unitech 2010 in Oslo, Norway during May 19–20, 2010. The goal of the Unitech conference was to encourage a stronger focus on the underlying technologies that help support achieving the goal of universal accessibility to information and communication technology. Of the 23 papers accepted for presentation at the conference, 6 are included in this issue in addition to one submitted in response to the open call. In the paper ‘‘On the usefulness of off-the-shelf computer peripherals for people with Parkinson’s Disease’’ Miriam Nes Begnum and Kyrre Begnum provide an assessment of the suitability of commercially available third party peripherals for computer users with physical disabilities, where they advocate the benefits of projector based pointing peripherals. Several countries are working toward electronic elections, and this move has several ramifications that even may affect democracy. The paper ‘‘An evaluation of web-based voting usability and accessibility’’ by Kristin Skeide Fuglerud and Till Halbach Rossvoll documents experiences with several electronic voting prototypes, looking at implications in the context of reduced functioning, and concluding that designers lack understanding of accessibility guidelines or chose to not prioritize these. Legislation, standards, guidelines and recommendation are important tools for validating whether systems are universally designed and the W3C WCAG2.0 has received a lot of attention. The paper ‘‘Validating WCAG versions 1.0 and 2.0 through Usability Testing with Disabled Users’’, by Dagfinn Romen and Dag Svanaes, describes a study which assessed the effectiveness of WCAG1.0 and WCAG2.0 as heuristics for website accessibility. The results show that WCAG2.0 is only capable of identifying half of the accessibility problems and that WCAG2.0 only is marginally better than WCAG1.0. Practitioners often speak of how technology needs to be designed to ensure that users with reduced functioning are included, sometimes forgetting the positive sides of new technologies and the unintended but new possibilities that new technologies opens up. In the paper ‘‘Universal Life: The Use of Virtual Worlds among People with Disabilities’’ Kel Smith gives an account of how second life can bring the rest of the world closer to users who are often excluded in the physical world due to their reduced functioning. Two of the papers in this special issue propose concrete technologies that may help achieve universal access. First, Hugo Fernandes, N Conceicao, H. Paredes, A. Pereira, P. Araujo and Joao Barroso, in the paper entitled ‘‘Providing accessibility to blind people using GIS’’, propose a strategy based on geographical information system that provides blind pedestrians enhanced navigation support when moving about outdoors. Second, the paper ‘‘EyeBlink Detection System for Human–Computer Interaction’’ by Aleksandra Krolak and Pawel Strumillo describes an implementation and extensive tests of a system that allows input via eye-blinks for users with physical disabilities who F. E. Sandnes (&) Faculty of Technology, Art and Design, Oslo and Akershus University College of Applied Sciences, Oslo, Norway e-mail: frodes@hio.no

Development and Implementation of Conflict-Based Assessment of Pedestrian Safety to Evaluate Accessibility of Complex Intersections

This paper develops and implements the Conflict-based Assessment of Pedestrian Safety (CAPS) methodology for evaluating pedestrian accessibility at complex intersections. In past years, a significant research has been done on pedestrian access to modern roundabouts and other complex intersection forms, including a significant focus on the accessibility for pedestrians who are blind. A majority of these studies have relied on actual street crossings by study participants under supervision of trained Orientation and Mobility (O&M) Specialist. These crossing studies were used to evaluate risk from a measurement of intervention events, where the O&M specialist had to physically stop the participant from crossing. While providing arguably the most accurate data for the crossing risk at a particular intersection, actual street crossings can be dangerous to the study participants, and are further very time consuming and expensive to conduct. The CAPS method presented in this paper emphasizes the use of conflict-based safety factors to quantify risk. The CAPS method relates pedestrian crossing decisions to advanced measurements of vehicle dynamics to estimate lane-by-lane conflicts. CAPS identifies the grade of conflict based on a score generated on a five-criterion rating scale. Each of these criteria or factors has different severity levels, and when combined, provides an overall risk rating of the crossing decision. The CAPS framework was applied to a study of blind pedestrian crossings at a multi-lane roundabout. The resulting risk scores were calibrated from actual O&M interventions observed during the study to give confidence in the CAPS performance. The calibrated CAPS framework correctly matched all (high risk) O&M intervention events, and further identifies other (lower risk) pedestrian-vehicle conflicts. The resulting method has the potential to allow for a faster and most importantly safer evaluation of complex intersections for pedestrian access. Since all factors are measured prior to the pedestrian stepping into the roadway, this approach is compatible with crossing indicator studies, where the participants merely indicate when they would cross, rather than actually stepping into the roadway. The CAPS framework therefore allows for a more objective and consistent safety assessment of pedestrian crossings in a research context without having pedestrians physically step into the roadway.

Auditory Detectability of Hybrid Electric Vehicles by Blind Pedestrians

Hybrid electric vehicles (HEVs) in low-speed operation may introduce a safety issue for pedestrians. This study compares the auditory detectability of HEVs and internal combustion engine vehicles among pedestrians who are legally blind. Independent travelers, with self-reported normal hearing, listened to binaural audio recordings of two HEVs and two internal combustion engine vehicles in three operating conditions and two different ambient sound levels. The operating conditions include approaching at a constant speed (6 mph), backing out at 5 mph, and slowing from 20 to 10 mph (as if to turn right). The ambient sound levels simulated a quiet rural [31.2 dB(A)] environment and a moderately noisy suburban [49.8 dB(A)] environment. Overall, participants took longer to detect HEVs (operated in electric mode). Vehicle type, ambient level, and operating condition had a significant effect on response time. Candidate countermeasures are discussed in terms of types of information provided (direction, rate of speed change), useful range of detection of vehicles by pedestrians, warning time, acceptability, and barriers to implementation.

Fusion of Data from Inertial Sensors, Raster Maps and GPS for Estimation of Pedestrian Geographic Location in Urban Terrain

Fusion of Data from Inertial Sensors, Raster Maps and GPS for Estimation of Pedestrian Geographic Location in Urban TerrainAn electronic system and an algorithm for estimating pedestrian geographic location in urban terrain is reported in the paper. Different sources of kinematic and positioning data are acquired (i.e.: accelerometer, gyroscope, GPS receiver, raster maps of terrain) and jointly processed by a Monte-Carlo simulation algorithm based on the particle filtering scheme. These data are processed and fused to estimate the most probable geographical location of the user. A prototype system was designed, built and tested with a view to aiding blind pedestrians. It was shown in the conducted field trials that the method yields superior results to sole GPS readouts. Moreover, the estimated location of the user can be effectively sustained when GPS fixes are not available (e.g. tunnels).

Acoustic Characteristics of Hybrid Electric Vehicles and Safety of Blind Pedestrians

Quieter cars, such as electric vehicles and hybrid electric vehicles (HEVs), may reduce auditory cues used by pedestrians to assess the state of nearby traffic and, as a result, their use may have an adverse impact on pedestrian safety. To document differences in the sound levels of HEVs and internal combustion engine (ICE) vehicles, the authors measured the sound pressure levels in one-third octave bands of three HEVs and three corresponding ICE vehicles for the following operating conditions: idle, backing up at 5 mph, approaching at a constant speed (6, 10, 20, 30, and 40 mph), accelerating from stop, and slowing from 20 to 10 mph at 3.28 ft/s2. Sound level results comparing the HEVs with the ICE vehicles are presented. In general, HEVs have lower sound levels than ICE vehicles for operating conditions below 20 mph; but above 20 mph, the sound from road–tire interactions dominates and the sound levels of the two vehicle types converge.

“Just go straight ahead”

ABSTRACTSpace is not a given. Rather, space is constructed through subjective experience and social interaction. This paper draws on the phenomenology of Schütz and Merleau-Ponty, the ethnomethodology of Garfinkel, autoethnography and the emergent field of the sociology of the senses to arrive at an account of how space is constructed and lived differently by blind and sighted individuals. Once having mapped the sensory and social infrastructures of the blind and sighted “styles of perception”, the paper considers how a blind pedestrian might try to elicit route descriptions from sighted strangers. Over 300 encounters were recorded. The transcripts of these encounters, most of which involved failures of communication, are analyzed for what they reveal about the lack of congruency between the two aforementioned styles of perception. The paper concludes by suggesting some adjustments to the social model of disability that comes out of Disability Studies, and offering some guidelines for the education of the senses that would substantially enhance the prospects for the meaningful communication of directions between blind and sighted persons.

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

This study examined the effect of cane tips and cane techniques on drop-off detection with the long cane. 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. 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. 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. 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. 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.

Mixed-Priority Pedestrian Delay Models at Single-Lane Roundabouts

This paper presents an approach for developing mixed-priority pedestrian delay models at single-lane roundabouts using behavioral crossing data. Mixed-priority refers to crosswalk operations where drivers sometimes yield to create crossing opportunities, but where pedestrians sometimes have to rely on their judgment of gaps in traffic to cross the street. The models use probabilistic behavioral parameters measured in controlled pedestrian crossings by blind pedestrians as part of NCHRP project 3-78a. While blind pedestrians clearly represent a special population of pedestrians, the developed delay model is structured to be applicable to any pedestrian population. Delay is predicted as a function of the probability of encountering a crossing opportunity in the form of a yield or crossable gap, and the probability of utilizing that opportunity, which are combined to produce an overall probability of crossing. The paper presents the theoretical approach to estimating the probability parameters and uses a multi-linear log-transformed regression approach to predict the average pedestrian delay. The final delay model explains 64% of the variability in the observed data and therefore represents a reasonable model for predicting pedestrian delay at single-lane roundabouts. The paper concludes with a discussion of how agencies can estimate the underlying probability parameters for existing or proposed roundabouts using empirical and theoretical approaches, and how pedestrian crossing treatments can be used in the context of the model to reduce average pedestrian delay. The research is important in light of the ongoing debate of the accessibility of modern roundabouts to pedestrians who are blind.

Detection of warning surfaces in pedestrian environments: The importance for blind people of kerbs, depth, and structure of tactile surfaces

Purpose. The overall purpose was to study whether and how persons with blindness detect warning surfaces with a long white cane in a real pedestrian environment after following a natural guidance surface to the warning surfaces. Of particular interest was the importance of kerb, depth, and structure of the warning surfaces.Method. A concurrently mixed methods approach, with a combination of observation using a structured form together with ‘think aloud’ and a structured interview, was used. It was done with well-defined samples and study sites in an inter-disciplinary research context.Results. The results show that the most important design characteristic for detection of the warning surfaces with a white cane is the structure of the surface, while the depth of the surface and availability of a kerb do not have any impact on the detection. A precondition was that there is a distinct natural guidance surface leading up to the warning surface.Conclusions. The probability among pedestrians with blindness to detect a tactile surface is not higher if the design solution has a kerb. This study also confirms the complexity of being a blind pedestrian in the traffic environment. The results can be used for evidence-based physical planning. The study also has implications for development of more efficient vision rehabilitation.

시각 장애인 보행안내를 위한 장애물 분포의 3차원 검출 및 맵핑

In walking guide robot, a guide vehicle detects an obstacle distribution in the walking space using range sensors, and generates a 3D grid map to map the obstacle information and the tactile display. And the obstacle information is transferred to a blind pedestrian using tactile feedback. Based on the obstacle information a user plans a walking route and controls the guide vehicle. The algorithm for 3D detection of an obstacle distribution and the method of mapping the generated obstacle map and the tactile display device are proposed in this paper. The experiment for the 3D detection of an obstacle distribution using ultrasonic sensors is performed and estimated. The experimental system consisted of ultrasonic sensors and control system. In the experiment, the detection of fixed obstacles on the ground, the moving obstacle, and the detection of down-step are performed. The performance for the 3D detection of an obstacle distribution and space mapping is verified through the experiment.

Working Concept of Accessibility

This research presents an analysis framework and associated performance measures for quantifying the accessibility of pedestrian crossings at modern roundabouts for pedestrians who are blind. The measures, developed under two ongoing national research projects, NCHRP Project 3-78A and a bioengineering research grant from the National Institutes of Health-National Eye Institute, attempt to isolate the components of the crossing task for a blind pedestrian into computable and replicable quantities that allow the comparison of accessibility across individuals or sites. The framework differentiates between crossing opportunities in the form of yields and crossable gaps and the utilization of these opportunities by the pedestrian. It further accounts for the amount of delay and risk involved in the crossing. The analysis framework and measures are demonstrated for two single-lane roundabouts in North Carolina evaluated under the aforementioned research projects. The application shows that the accessibility of a pedestrian crossing to a blind pedestrian is characterized by a combination of different measures and further depends on crossing geometry, traffic volume, driver behavior, and the travel skills and risk-taking behavior of the individual. With successful demonstration at roundabout crosswalks, the analysis framework is hypothesized to have broader application to unsignalized pedestrian crossings, including midblock locations.

Toward Roundabout Accessibility—Exploring the Operational Impact of Pedestrian Signalization Options at Modern Roundabouts

This paper explores the use of pedestrian signalization options for crosswalks at one- and two-lane roundabouts to enable these facilities to be accessible to pedestrians with vision impairments. Motivated by uncertainties about the safety of roundabouts for blind pedestrians, audible pedestrian signals hold promise for safely regulating the interaction of vehicles and pedestrians at these facilities. However, the use of pedestrian signals at roundabouts is controversial because of the potential for queue spillback into the circulating lane and delays to vehicular traffic. The objective of this work is to quantify pedestrian-induced delays and queuing impacts of a pedestrian signal placed at the busiest approach of a modern roundabout. The analysis is performed using a calibrated microsimulation model and includes assessment of innovative solutions for crossing geometry and phasing scheme at one-lane and two-lane roundabouts. The results suggest that the impact of pedestrian signals at roundabouts is greatest as vehicle volumes approach capacity, but that vehicle delay and queuing can be mitigated through innovative signal configurations. The findings are important in light of recent discourse concerning the accessibility of roundabouts to pedestrians with vision impairments that may ultimately move towards a requirement for signalization for certain facility types.

Accessible Pedestrian Signals at Complex Intersections

Pedestrians with vision impairments often have to cross streets at unfamiliar signalized intersections. The results are reported of research on crossings by blind pedestrians at complex intersections before and after the installation of accessible pedestrian signals (APS) and again following the installation of innovative device features. Objective data on measures of street crossing performance by 56 participants were obtained at four intersections, two each in Charlotte, North Carolina, and Portland, Oregon. The analysis includes broad measures of crossing timing, wayfinding, and independence. After APS installation, delay in starting to cross was reduced by approximately 2 s, and there was significant improvement in independently determining a safe time to cross, beginning to cross during the “Walk” signal, and completing crossings before the onset of perpendicular traffic. Some measures of wayfinding and related measures of independence also improved in Portland. Additional device features introduced after the first postinstallation testing session led to additional improvements in wayfinding during a second postinstallation test in Charlotte.

WAYFINDING BEHAVIOR AND SPATIAL COGNITION

The purpose of this research is to clarify the spatial cognition of the visually impaired in model courses. Experimental courses were a straight course without any obstructions, and 6 kinds of bent course. Subjects were 5 totally blind pedestrians, 5 eye-masked pedestrians, and 5 normal sighted pedestrians. The results are as follows. (1) In the case of the blind subjects, the wider the angle of the corner is, the lower the rate of the independent walk is. (2) The behavior of losing the way of the eye-masked is 2 times as much as that of the blind. The incidence of losing the way at the corner is 85 %. (3) In the correct answer for sketch map, the score of the blind is 90 points, while that of the eye-masked is 50 points. Even if the angle of the corner changes, the blind can draw the sketch map correctly. (4) At the destination, the difference of the direction angle of the blind is 19° and that of the eye-masked is 51°.

Variability in stepping direction explains the veering behavior of blind walkers.

Walking without vision results in veering, an inability to maintain a straight path that has important consequences for blind pedestrians. In this study, the authors addressed whether the source of veering in the absence of visual and auditory feedback is better attributed to errors in perceptual encoding or undetected motor error. Three experiments had the following results: No significant differences in the shapes of veering trajectories were found between blind and blindfolded participants; accuracy in detecting curved walking paths was not correlated with simple measures of veering behavior; and explicit perceptual cues to initial walking direction did not reduce veering. The authors present a model that accounts for the major characteristics of participants' veering behavior by postulating 3 independent sources of undetected motor error: initial orientation, consistent biases in step direction, and, most important, variable error in individual steps.