Janet M Barlow

Directional guidance from audible pedestrian signals for street crossing

Typical audible pedestrian signals indicate when the pedestrian walk interval is in effect but provide little, or even misleading information for directional alignment. In three experiments, blind and blindfolded sighted adults crossed a simulated crossing with recorded traffic noise to approximate street sounds. This was done to investigate how characteristics of signal presentation affected usefulness of the auditory signal for guiding crossing behaviour. Crossing was more accurate when signals came only from the far end of the crossing rather than the typical practice of presenting signals simultaneously from both ends. Alternating the signal between ends of the crossing was not helpful. Also, the customary practice of signalling two parallel crossings at the same time drew participants somewhat toward the opposite crossing. Providing a locator tone at the end of the crossing during the pedestrian clearance interval improved crossing accuracy. These findings provide a basis for designing audible pedestrian signals to enhance directional guidance. The principal findings were the same for blind and sighted participants and applied across a range of specific signals (e.g. chirps, clicks, voices).

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

This paper describes the development and implementation of the conflict-based assessment of pedestrian safety (CAPS) methodology for the evaluation of pedestrian accessibility at complex intersections. Significant research has explored pedestrian access to modern roundabouts and other complex intersections, and a significant focus has been placed on accessibility for pedestrians who were blind. A majority of these studies relied on actual street crossings by study participants under the supervision of a trained orientation and mobility specialist. These crossing studies quantified risk from a measurement of intervention events, in which the orientation and mobility specialist had to physically stop the participant from crossing. Although such studies provide useful data on the crossing risk at a particular intersection, street crossings can be dangerous to the study participants and are time-consuming and expensive to conduct. The CAPS method emphasizes the use of conflict-based safety factors to quantify risk in a framework compatible with indicator studies. This method relates pedestrian crossing decisions to advanced measurements of vehicle dynamics to estimate lane-by-lane conflicts and identifies the grade of conflict on the basis of a five-criterion rating scale. The CAPS framework was applied to a study of crossings by blind pedestrians at a multilane roundabout. The resulting risk scores were calibrated from the actual orientation and mobility interventions observed during the study. The calibrated CAPS framework correctly matched all (high-risk) orientation and mobility intervention events and further identified other (lower-risk) pedestrian–vehicle conflicts. The CAPS framework provides a more efficient, objective, and consistent safety assessment of pedestrian crossings in a research context, without the need for pedestrians to step into the roadway.

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.

Accessible Pedestrian Signals at Complex Intersections: Effects on Blind Pedestrians

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.

CHALLENGES OF UNFAMILIAR SIGNALIZED INTERSECTIONS FOR PEDESTRIANS WHO ARE BLIND: RESEARCH ON SAFETY

Pedestrians who are blind or visually impaired often travel in areas that are unfamiliar to them and cross at signalized intersections. Results are reported of testing street crossing by blind pedestrians at complex, unfamiliar signalized intersections without accessible pedestrian signals. There will be further reports on these results. The focus is on descriptive analysis of broad measures of safety, orientation, and need for assistance in crossing. Objective data on 12 measures of street-crossing performance were obtained at four intersections (two in each of two cities). In each city, 16 blind participants crossed at unfamiliar, complex signalized intersections without accessible pedestrian signals. Results confirm that blind pedestrians have considerable difficulty locating crosswalks, aligning to cross, determining the onset of the walk interval, maintaining a straight crossing path, and completing crossings before the onset of traffic perpendicular to their path of travel. Accessible pedestrian signals will be installed at the four intersections, and postinstallation data will be used to determine recommendations for accessible pedestrian signal characteristics and installation.

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.

Accessible Pedestrian Signals: Effect of Device Features

The U.S. Access Boards Draft Guidelines for Accessible Public Rights-of-Way recommends the use of push-button-integrated accessible pedestrian signals (APSs). This research compared the effect of specific features of push-button-integrated APSs on the ability of blind pedestrians to locate and correctly use push buttons and to cross accurately during the pedestrian phase. A rapid-tick walk signal promoted the fastest onset of crossing compared with speech messages and bird calls and is therefore the preferred signal. However, speech walk indications are needed where two APSs are mounted on the same pole. Although variations in the standard features made little difference to users who were thoroughly familiar with devices, empirical evidence from participants with less knowledge of the devices as well as subjective data lead to the recommendation that APS devices include a push-button locator tone, a rounded push button with an activation tone or message, a tactile arrow incorporated into the push button, responsiveness to ambient sound, and a push-button information message and beaconing in response to an extended button press.

Locator Tones for Pedestrian Signals

The two primary problems experienced by visually impaired persons at pedestrian-actuated intersections are determining whether there is a pushbutton and locating the push button. Many countries use accessible pedestrian signals much more widely than has been done in the United States, and a number of these—including Australia, Hong Kong, Sweden, Denmark, Germany, Belgium, and Austria—routinely require the use of a locator tone. Typically emanating from the push-button housing, a pushbutton locator tone indicates to pedestrians that they are expected to push a button to request a pedestrian phase. It enables visually impaired pedestrians to locate the push button quickly and efficiently. Research was undertaken to determine the effect of locator tone repetition rate on efficiency of pedestrians’ location of the push-button pole. Repetition rates of 1.0 and 1.5 Hz resulted in equal pole location speed, faster than that for the 0.5 Hz repetition rate, and were preferred over the 0.5 Hz repetition rate. Locator tones 2 dB above ambient sound resulted in faster pole location than did tones 5 dB and 10 dB above ambient sound. Push-button locator tones should have a standardized repetition rate between 1.0 Hz and 1.2 Hz so that it may be ensured that visually impaired pedestrians can efficiently locate push buttons. Locator tones need be no more than 5 dB louder than ambient traffic sound.

Guidebook on Pedestrian Crossings of Public Transit Rail Services

This report presents a wide array of engineering treatments to improve pedestrian safety for three types of public transit rail services: light rail, commuter rail, and streetcar. The Guidebook is a resource that addresses key pedestrian safety issues associated with public transit rail services; presents pedestrian crossing issues associated with the National Environmental Policy Act of 1969 and the Americans with Disabilities Act; summarizes readily available decision flowcharts used to make decisions regarding pedestrian treatments at rail crossings; presents information for 34 pedestrian treatments used at rail crossings, grouped into eight appropriate categories; and includes four case studies that examine specific decisions with respect to pedestrian- rail crossings.

Design Guidance for Channelized Right-Turn Lanes

This report documents and presents the results of research to develop design guidance for channelized right-turn lanes. Observational field studies were conducted at 35 intersection approaches in cities to assess pedestrian crossing behavior, motorist yield behavior, and the interaction between pedestrians and motor vehicles at channelized right-turn lanes. Simulation modeling was performed to quantify the traffic operational benefits of channelized right-turn lanes with various types of traffic control and to compare the delay reduction of channelized right-turn lanes and conventional right-turn lanes. Crash data for nearly 400 intersection approaches in Toronto, Ontario, Canada, including intersection approaches with channelized right-turn lanes, conventional right-turn lanes, and shared through/right-turn lanes, were analyzed to compare the safety performance of the three right-turn treatment types. The research results indicate that channelized right-turn lanes have a definite role in improving operations and safety at intersections. However, to achieve these benefits they should have consistent design and traffic control and should be used at appropriate locations. The research provides design guidance for channelized right-turn lanes that addresses geometric elements such as crosswalk location, special crosswalk signing and marking, island type, radius of turning roadway, angle of intersection with cross street, acceleration and deceleration lanes, and traffic control.