Blind Pedestrians Access to Roundabouts and Other Complex Intersections
The Institute for Transportation Research and Education (ITRE) is centrally involved in research addressing questions and concerns of pedestrian accessibility to roundabouts and complex intersections. The focus of this ITRE research branch is on accessibility concerns at modern roundabouts and signalized intersections with channelized right turn lanes. Both types of facilities pose challenges to pedestrians who are blind, including:
- Presence of free‐flowing traffic (typically) not controlled by a signal
- Elevated levels of background noise generated by other movements at the intersection
- Curved vehicle trajectories that make it difficult to discern traffic patterns
- Lack of reliably auditory cues that can be used to identify crossing opportunities
- Mixed‐priority crossing challenges, where pedestrians can cross either in a large gap between vehicles, or in front of a stopped (yielding vehicle)
- Unreliable driver behavior, where only some proportion of traffic yields to pedestrians
- Inconsistent use of wayfinding cues that can help the pedestrian to find the intended crossing location
The crossing challenges are recognized by the accessibility community and are an increasing focus of engineering studies as well. More specific requirements for accessibility are currently being drafted and reviewed by the United States Access Board. ITRE's research involvement in this area is plays an important role in the considerations of the US Access Board, and provides a service to pedestrians with vision disabilities.
The research in this area is being supported by an ongoing Bioengineering Research Partnership by the National Eye Institute of the National Institutes of Health (NIH, 1), and National Cooperative Research Program project NCHRP 3‐78a (2). More recently, ITRE has been asked to assist the Road Commission of Oakland County, Michigan with the evaluation of several treatments to assist blind pedestrians to cross at two busy multi‐lane roundabouts (3).
The NIH project (1) is currently in its second phase of funded research and represents a partnership between ITRE and Western Michigan University (PI), Johns Hopkins University, Vanderbilt University, Boston College, and Accessible Design for the Blind. The first phase (2001‐2006) of the project performed extensive work on identifying crossing challenges of pedestrians who are blind at complex intersections and established the fundamental research in this area. The focus areas were
- modern roundabouts and channelized turn lanes,
- design and placement of audible pedestrian signals,
- challenges for pedestrians with low vision, and
- research on the auditory environment at these crossing locations.
In the ongoing second phase of the grant (2007‐2012), the focus has shifted to more advanced challenges, such as
- technologies to detect driver yielding events using video‐based detection technologies
- research on the challenges posed by quiet cars and hybrid vehicles
- simulation of the auditory crossing environment at roundabouts
- evaluation of crossing alignment and wayfinding treatments.
This research is funded through 2012.
Automated Yield Detection System
As part of this project, ITRE has conceptualized, developed and field‐evaluated a system to automatically detect the presence of yielding vehicles. The Automated Yield Detection System (AYDS) uses video‐based sensing algorithms in combination with a traffic signal controller and audible pedestrian signals to assist blind pedestrians to cross at otherwise unsignalized crossing locations.
The system was successfully field‐tested in April 2008 and showed promised for further development. The system is portable on ITRE's instrumented data collection trailer and features wireless video and detection communications technology to allow deployment in a variety of settings.
The following videos show how AYDS works.
- This video presents an overview of the Automated Yield Detection System and demonstrates how the experimental accessibility technology can assist pedestrians who are blind to cross at modern roundabout intersections. The fully portable AYDS uses video-based algorithms, a 40-foot telescoping mast arm, wireless technology, and signal control hardware to detect when a vehicle yields to a pedestrian and to auditorily relay this information to a pedestrian who is blind.
View video (WMV, 5 minutes)
- This video clip shows the operations of the AYDS algorithm as seen by the research team. A total of four time-synchronized video views are shown.
- The top left video shows a street-level view of the pedestrian crosswalk at the roundabout.
- The top right video shows a view of the detection hardware used for trouble shooting.
- The bottom left and right views show the detection algorithms for exit and entry lane of the roundabout, respectively.
In the video, the AYDS successfully detects a yielding vehicle in the exit lane (approximately 55 seconds into the clip), which prompts the system to send an auditory signal to the waiting blind pedestrian.
View Video (WMV, 1 minute)
NCHRP Project 3‐78 (2) specifically focuses on the identification and evaluation of infrastructure-based treatments that can assist pedestrians who are blind to cross at roundabouts and channelized turn lanes. In this ITRE‐led project, the research team has tested and evaluated various treatments ranging from low-cost flashing beacons and audible sound strips, to raised crosswalks and Pedestrian Hybrid Beacons, which are also known as HAWK signals. ITRE is partnering with Western Michigan University, Boston College, Kittelson and Associates, Inc., and Accessible Design for the Blind on this important project. The final project report is forthcoming in 2010.
ITRE is further partnering with Western Michigan University in the evaluation of pedestrian crossing treatments at two three‐lane roundabouts in Oakland County, Michigan (3). The treatment installation and study were prompted by a law suit, in which the plaintiffs challenged the accessibility of these busy roundabouts. The evaluation includes study of advanced Pedestrian Hybrid Signals and Rectangular Rapid Flashing Beacons. The study will be completed at the end of 2010.
Interactive Crossing Visualizations
Computer-generated graphics showing various crossing solutions intended to assist blind pedestrians to cross the street at roundabouts and other complex intersections are presented as visualizations. The visualizations were created as part of National Cooperative Highway Research Program (NCHRP) Project 3-78a, and were generously donated by the New York State Department of Transportation to assist the project team.
The visualizations show accessibility treatments including pedestrian signage, pedestrian-actuated flashing beacons, raised crosswalks, sound strips, and pedestrian hybrid beacons (also known as "HAWK" signals).
All treatments are visualized for different crosswalk geometries (proximal, offset, and distal) and are shown from overhead, pedestrian, and driver vantage points. The visualizations are intended to convey what these crossing solutions look like to engineers, planners, policy-makers, and the general public.
Dr. Bastian Schroeder, Assistant Director, Highway Systems Group
919-515-8565 | firstname.lastname@example.org