David Guth

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.

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.

Effectiveness of Audible and Tactile Heading Cues at Complex Intersections for Pedestrians Who Are Blind

This research extends the results of laboratory research on wayfinding at intersections for pedestrians who are blind. Standard accessible pedestrian signals (standard APS), a prototype beaconing APS, and a raised guide strip were evaluated for their ability to assist in establishing and maintaining a heading for street crossings. Experiments were conducted at large, complex signalized intersections in Alpharetta, Georgia; Austin, Texas; and Towson, Maryland. Both the guide strip and the beaconing APS resulted in more accurate street crossing performance than standard APS with respect to alignment (i.e., initial heading) accuracy, rates of being within the crosswalk, distance from the center of the crosswalk at various points during crossing, and the likelihood of being well outside the crosswalk [6 ft (2 m) or more]. For the most part, performance with the guide strip or the beaconing APS was equivalent. Limitations and additional concerns with respect to these two treatments are discussed.

Space saving statistics: An introduction to constant error, variable error, and absolute error.

Abstract Research results in the field of orientation and mobility (O&M) and in related fields are increasingly being reported in terms of subjects’ constant error, variable error, and absolute error. These three descriptive statistics are used to quantify fundamentally different characteristics of distributions of spatially directed behavior. This article introduces the three statistics, illustrates them with examples, and argues that their use in O&M research and practice is a positive development for the field.

Wayfinding Problems for Blind Pedestrians at Noncorner Crosswalks: Novel Solution

To travel independently, pedestrians with visual impairments must be able to locate crosswalks and align accurately for crossing streets. This action is especially challenging where crossings are not located at street corners and cues for locating the crosswalk and aligning to cross in the direction of travel on the crosswalk may be inadequate. This research compared midblock and roundabout crossings with curb ramps and detectable warnings but no other consistent cues for locating the crosswalk and no cues specifically intended to provide alignment and heading information, with the same crossings with the addition of a 24-in.-wide prototype surface of raised bars oriented perpendicular to the direction of travel on the crosswalks. This treatment was installed beside the detectable warnings and extended across the sidewalk. It was hypothesized that this surface would assist with both locating the crosswalk and establishing accurate alignment with the crosswalk. Sixteen participants having little or no vision failed, on average, to locate the crosswalk on the initial approach on 2.4% of their attempts for crosswalks having the guidance surface, while without the guidance surface, participants failed to locate the crosswalk on the initial approach on an average of 17.9% of their crossing attempts. With the guidance surface, participants aligned correctly on average on 77.3% of their trials, while without the surface the rate of correct alignment was 52.1%.