Accessibility of modern roundabouts and channelized turn lanes to pedestrians with vision disabilities has been a focus of recent and ongoing research. Initial research results documenting the crossing challenges for pedestrians with vision disabilities at these facility types motivated the original NCHRP Project 3-78A research effort and had an influence on language in the Proposed Accessibility Guidelines for Pedestrian Facilities in the Public Right-of-Way (draft PROWAG) published by the U.S. Access Board in 2011. That document provides technical specifications for making sidewalks and intersections in the public rights-of-way compliant with the American with Disabilities Act (ADA). Specifically, the provision of a pedestrian-actuated signal with an Accessible Pedestrian Signal (APS) fulfills accessibility requirements for multi-lane approaches at roundabouts and channelized turn lanes in the draft PROWAG. However, ADA regulations allow the use of alternative treatments, if those treatments provide facilities (crosswalks) that are “accessible to and usable by" individuals with disabilities (called equivalent facilitation in ADA regulations). The draft PROWAG does not specifically discuss crossing treatments for single-lane approaches on these facilities. With the impending publication of PROWAG and its expected adoption by the U.S. Department of Justice and U.S. Department of Transportation, municipalities and state DOTs need more specific guidance on what may constitute equivalent facilitation to pedestrians with vision disabilities at these facility types.
NCHRP Project 3-78A was tasked with exploring crossing solutions for single-lane and multi-lane crossings. The research was based on the premise that other treatments exist besides an APS-equipped signal that can establish access to these facilities to pedestrians who are blind, while reducing installation cost and impact to vehicular traffic. In particular, the NCHRP Project 3-78A work (published in NCHRP Report 674: Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities) tested two treatments at a two-lane roundabout that showed promise in terms of reducing pedestrian delay and risk. The work accomplished during NCHRP Project 3-78A sets the stage for continuing research. First, the research developed a framework for quantifying pedestrian accessibility, thus enabling a direct comparison of the accessibility impacts of two or more conditions (for example, evaluation of pre-post treatment effect; comparison of two test sites; or contrast of different pedestrians at a site). Second, the NCHRP Project 3-78A research tested several crossing treatments that showed potential for improving pedestrian access to two-lane crossings (e.g., raised cross walk (RCW) and pedestrian hybrid beacon (PHB)), and others that left pedestrians with significant challenges when attempting to cross at single-lane channelized turn lane crosswalks. The research found that effectiveness of crossing treatments varied depending on the site characteristics, and that more research at additional sites is needed to strengthen the results. Third, the research developed ways to extend the research to other sites, geometries, and traffic volume patterns through mathematical delay models and through modeling in a micro-simulation environment.
Combined, these three aspects provide a sound experimental and practical base for follow-up research that help address issues and questions that confront municipalities and state DOTs: Which (if any) are the most cost-effective, site-specific treatments that successfully establish equivalent facilitation to pedestrians with vision disabilities under prevailing geometric and operational conditions, while balancing the impact to the traveling public? The completed NCHRP Project 3-78A effort devoted a large portion of time to developing a short list of treatments, to identifying treatment locations, and to defining an analysis framework and performance measures for pedestrian accessibility. With those pieces in place, and with the initiative taken by agencies across the country, there is significant momentum for continued research leading towards decision support for state and local governments in this area.
The objective of this research is to develop guidelines for the installation of pedestrian crossing solutions at roundabouts and channelized turn lanes that address accessibility for pedestrians with vision disabilities. Specifically, guidelines need to consider multiple alternatives for a range of geometric and traffic operational conditions. The guidance needs to focus on solutions that can be incorporated in designs now and can be installed and fully activated when the roundabout is opened to the public.
The research will efficiently extend field work by capitalizing on the findings from NCHRP Project 3-78A and on initiatives taken by agencies across the country in installing solutions. The field work will cover selected channelized turn lanes, single-lane roundabouts, and two-lane roundabouts at a greater sample size than NCHRP Project 3-78A, that will be made possible by a condensed and well-targeted data collection protocol that reduces the number of participants per site, while maintaining statistical power. Further, each proposed case will include multiple (up to three) crosswalks in close proximity for added sample size. The research will further be supported by extension of the research results to other geometries and traffic patterns through mathematical modeling and simulation. The goal of this effort is to define as accurately as possible the operational conditions under which certain solutions are thought to establish accessibility. The final report will provide engineers and others with more specific guidance for when (and if) a particular solution is recommended.
Task descriptions are intended to provide a framework for conducting the research. The NCHRP is seeking the insights of proposers on how best to achieve the research objective. Proposers are expected to describe research plans that can realistically be accomplished within the constraints of available funds and contract time. Proposals must present the proposers' current thinking in sufficient detail to demonstrate their understanding of the problem and the soundness of their approach.
NCHRP Project 3-78A, “Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities,” was completed in May 2010 following 4 years of research. The final project report identified research needs, including additional data collection and analysis at channelized turn lanes, single-lane roundabouts, and multi-lane roundabouts, in order to generate a sufficiently large sample size of observations to guide future policy decisions on questions of accessibility. In Phase I of Project 3-78B, the focus is on site selection and development of a research plan and data collection schedule.
(1). Conduct a national outreach to identify test locations, pre-existing treatments or solutions, and agencies that are installing treatments or solutions for testing in the short term. The focus of NCHRP Project 3-78B is on additional data collection at existing sites, i.e., those already having some form of pedestrian crossing treatment(s) or solution(s) installed. There are many such installations across the country, but a thorough inventory of such locations to match facility types is needed. In Task 1, the research team will contact state and local agencies to compile an inventory of potential test sites. (2). Develop a data collection plan for field work. NCHRP Project 3-78A research applied a statistically rigorous data collection protocol that focused on in depth, or detailed observations at a limited number of sites, rather than evaluating a breadth of locations. This initial focus was necessary to fully understand inter-participant variability and obtain results with high statistical power. With this prior protocol in place, a more condensed data collection protocol is needed that will allow for the evaluation of many sites more efficiently. While an assessment of select treatments in NCHRP Project 3-78A showed potential for some solutions, a broader sample size is needed to build confidence in their measured effectiveness. In Task 2, the research team will develop an appropriate data collection protocol that maximizes collection efficiency, while assuring that the results are statistically meaningful. (3). Develop a detailed Phase II research plan and data collection schedule, based on the Task 1 identification of test locations and the Task 2 data collection protocol. The Phase II research plan will consider geographical diversity of test locations and other characteristics in order to lay out a detailed schedule. At a minimum, the work plan should include the geometric and operational conditions under which each potential solution selected is expected to be appropriate, the number of field sites required for testing, a list of potential sites, the research methodology, and the evaluation criteria. It is acceptable to identify multiple crossing solutions to be tested at a given location.(4). Submit an interim report, within 6 months, to document the results of Tasks 1 through 3 for review by the NCHRP. The contractor will be expected to meet with the NCHRP approximately 1 month later. A PowerPoint presentation provided at the interim meeting should be suitable, after revision, for use by panel members and others in describing the research and for posting on the project website. The research agency shall not proceed to Phase II without NCHRP approval of the interim report and the updated work plan. (5). Revise the interim report (following the panel meeting) in an accessible format suitable for publication on the NCHRP website.
(6). Execute the Phase II research plan, including the field experiments, in accordance with the approved work plan. (7). Analyze the new data and combine the results with existing data, with an emphasis on establishing operational guidelines for accessibility, to include: (a) identification of crossing locations (e.g., crosswalks) by drivers; (b) identification of crossing locations by pedestrians with vision disabilities; and, (c) identification of crossable gaps in traffic by pedestrians with vision disabilities. (8). Extend field results through modeling and simulation to cover a broader range of geometries and operational conditions. (9). Develop cost estimates for the solutions that are proposed. The estimates should include initial implementation costs as well as operation and maintenance costs over the life-cycle of the solutions. These cost estimates should apply only to solutions at newly constructed roundabouts and channelized right turn lanes, not to retrofits.(10). Develop guidelines for treatment installation to establish accessibility. Recommend treatments and/or changes that could potentially be incorporated into existing transportation procedures and practice documents, including the AASHTO Policy on Geometric Design of Highways and Streets and the FHWA Manual on Uniform Traffic Control Devices.(11). Submit a final report that documents the entire research project. At a minimum, the report should include a summary of all tasks completed, details of the work conducted to select the crossing solutions evaluated in Phase II, complete documentation of the experiments performed in Task 6, accessibility guidelines proposed in Task 7, a summary of the cost information developed in Task 9, and any changes in recommended transportation engineering procedures or practices resulting from this research. Where appropriate, the report should include appendices with recommended language for potential inclusion in the AASHTO Policy on Geometric Design of Highways and Streets; the AASHTO Guide for the Planning, Design, and Operation of Pedestrian Facilities; the AASHTO Guide for the Development of Bicycle Facilities; the FHWA Manual on Uniform Traffic Control Devices; the Traffic Control Devices Handbook; and other appropriate documents.
STATUS: Complete. Publication is pending for a guidebook as NCHRP Report 834. TRB's National Cooperative Highway Research Program (NCHRP) Web-Only Document 222: Guidelines for the Application of Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities supplements NCHRP Report 834: Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrian with Vision Disabilities – A Guidebook. The Report 834 guidebook provides guidance to engineers and planners on the design of roundabouts and channelized turn lanes for accessibility. This web-only document 222 supplements the guidebook with additional documentation and background on the underlying research.
The accessibility of modern roundabouts and intersections with channelized turn lanes is an important civil rights challenge in the United States that has broad potential implications for engineering practice in this country. NCHRP Report 834 and web-only document 222 build on the results of NCHRP Report 674: Crossing Solutions at Roundabouts and Channelized Turn Lanes for Pedestrians with Vision Disabilities. It provides a framework for empirical study and analysis of accessibility performance, documents field testing of several treatments, and provides a research extension through modeling and simulation to expand the results beyond the field-tested sites.