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10 This report explores concerns about the accessibility of two complex intersection forms to pedestrians who are blind: intersections with channelized turn lanes (CTLs) and mod- ern roundabouts. Crossing challenges for blind pedestrians have been established through research (e.g., Guth et al. 2005, Ashmead et al. 2005, Schroeder et al. 2006) for both types of intersections. The emphasis of this project was on the identi- fication of crossing treatments that can assist blind travelers in accessing these facilities at reasonable risk and with a rea- sonable amount of delay. Channelized turn lanes are a very common intersection treatment, intended to allow heavy right-turning movements to bypass an otherwise signalized intersection. Crosswalks at CTLs are oftentimes unsignalized in the United States, and pedestrians are therefore required to make crossing decisions independently, without assistance from an accessible pedes- trian signal (APS) or other audible device. Modern roundabouts are increasingly being adopted by the transportation community in the United States due to their ability to process balanced and unbalanced traffic patterns, their aesthetic appeal, and most importantly, their documented safety benefits (e.g., Rodegerdts et al. 2007, FHWA 2000, Persaud et al. 2000). Similar to CTLs, there remain concerns about the accessibility of modern roundabouts to certain groups in the pedestrian community. Of particular concern is the accessibility to pedestrians with blindness or low vision (U.S. Access Board 2003). Roundabouts and CTLs, like other unsignalized inter- sections, present challenges that are different from signalized intersections for individuals with blindness and other visual impairments. Roundabouts have relatively free-flowing traf- fic patterns, and they lack the more predictable pattern of traf- fic movement that is associated with signalized intersections. This reduced predictability sometimes makes it difficult to judge when it is safe to cross at roundabout crossings using auditory cues alone. Judging gaps in traffic that afford cross- ing, or determining that vehicles have yielded just upstream of the crosswalk, can be difficult, particularly when other sounds mask the sounds of approaching or yielded vehicles. Another key challenge for roundabouts and CTLs is that they often carry higher volumes than other typical two-way stopped control (TWSC) and all-way stopped control (AWSC) inter- sections, which are also unsignalized. In addition to determining when to cross the road, pedestri- ans with vision impairments must identify where to cross and which way to walk during the crossing, and must determine when they have arrived at their destination curb or island (Guth et al. 1989). These challenges are common to all pedestrian crossings, but are exacerbated at roundabouts and CTLs due to the unexpected, non-perpendicular alignment of the crosswalk. While prior research has demonstrated and documented the crossing challenges for blind pedestrians at these facilities (e.g., Guth et al. 2005, Ashmead et al. 2005, Schroeder et al. 2006), it has failed to develop and test crossing solutions that would improve the accessibility of these facilities. The objec- tive of NCHRP Project 3-78A was to fill that void and evaluate a range of pedestrian crossing treatments in controlled field experiments with the goal of providing decision support to engineers and policy makers. Safety Is Not Synonymous with Access The underlying premise of this research is that while safety and access of a facility are related, the two terms are not syn- onymous. A facility could be considered safe if the crash rate at the facility is low. However, effective access must be judged by the extent to which any individual or group of individuals limits its use of a facility based on a real or perceived belief that the facility is unsafe or extraordinarily difficult to use. The absence of recorded pedestrian crashes, especially those involv- ing older pedestrians, children, or those with visual and/or physical impairments, does not constitute proof that a facil- ity is accessible, nor does the presence of crashes constitute C H A P T E R 1 Introduction
proof that it is inaccessible. Accessibility must be evaluated in terms of direct observation that a facility can be used by all persons, independent of whether they are actually observed using it. For the question of the accessibility of complex inter- sections to pedestrians who are blind, a conventional engineer- ing analysis of pedestrian crashes therefore does not provide the necessary information. Comparing Roundabouts and Channelized Turn Lanes When attempting to cross a CTL or the entry/exit lane of a roundabout, a blind pedestrian must decide, largely on the basis of auditory cues, when it is safe to cross. Both types of facilities share the following common characteristics with respect to the crossing task for blind pedestrians: ⢠Use of (typically) unsignalized pedestrian crossings without an audible device that assists in determining signal status, ⢠Potentially high levels of ambient noise associated with background traffic at the main intersection or roundabout, ⢠Free-flowing traffic at the exit portion of the roundabout crossing and at non-yield-controlled CTLs, ⢠Challenge of curved vehicle paths that differ from more standard orthogonal intersections, ⢠Ambiguity about vehicle trajectories between through/ circulating and turning/exiting traffic, ⢠Lack of information identifying the sites as different from conventional orthogonal intersections, and ⢠Crossings that originate from a refuge island where traffic moves in front of and behind the pedestrian. However, the two types of facilities also exhibit some signif- icant differences that need to be emphasized. Through-vehicle (and potentially turning-vehicle) speeds are expected to be higher in the vicinity of a CTL, resulting in an elevated level of background noise and potentially different behavior in terms of drivers yielding to pedestrians. The difficulty of the auditory discrimination at a CTL will be influenced by a number of factors, such as (a) whether the CTL has a dedicated decel- eration lane and the length of that lane, (b) whether the CTL has a dedicated acceleration lane and the length of that lane, (c) the radius of the channelized lane and the associated design speed, and (d) whether vehicles exiting the channelized lane are able to merge with traffic with or without any reduction in speed. The last point is principally associated with the pres- ence and length of a downstream acceleration lane. For roundabout crossings, a range of different roundabout geometries exist that affect the crossing task. Roundabouts vary in the number of approach lanes, the number of circu- latory lanes, the inscribed circle diameter, crossing point dis- tance from circulating traffic, and most importantly traffic patterns, including volumes, gap distributions, and vehicle classification. Scope of Work The objective of this research was to explore through empir- ical research geometric designs, traffic control devices, and other treatments that will enable safe crossings at roundabouts and CTLs for pedestrians who are blind. The results of this research also will be useful to engineers, the accessibility com- munity, policy makers, and the general public to aid in under- standing the specific challenges experienced by pedestrians who are blind at these facilities. It is only through understand- ing the components of the crossing task and the particular challenges involved that solutions can be developed, installed, and evaluated appropriately. The focus of this research was on people who are blind, and therefore the term âblind,â rather than âvisually impaired,â will be used throughout this document. In this context, peo- ple who are blind are defined as those who have only light- perception or less vision and who are therefore unable to identify traffic patterns, signs, markings, or signal displays. The research clearly has implications for other pedestrians with vision impairments, which includes those with limited or low vision. But all studies performed through this research involved only pedestrians who are blind according to the definition above. The guidance in this report is intended to provide practi- tioners with useful information related to establishing safe crossings at roundabouts and CTLs for pedestrians who are blind. The specific focus areas are to provide guidance on: ⢠Identifying when a pedestrian crossing problem may be present, ⢠Tying treatment solutions to specific crossing challenges faced by the pedestrian population, ⢠Conducting pedestrian/vehicle studies that help identify appropriate treatment strategies, ⢠Quantifying the accessibility performance 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. This report is not intended to provide practitioners with requirements of when to install specific treatments, which is a policy decision. Instead, the team provides useful information on the concept of accessibility and how to provide improved crossing environments based on the pedestrian crossing task at hand. 11
The research results do serve to introduce a structured and measurable framework for quantifying the chief operational parameters of accessibility (Schroeder et al. 2009) and to estab- lish decision support through empirical research results. How- ever, the results do not provide a comprehensive evaluation of all potential treatments and all variations of sites. Such effort is considered well beyond the scope and budget of a single project. The authors do hope, however, that the reader will find the research findings and discussions in this document useful and that the results provide a common baseline for dis- cussion of questions of accessibility at these locations. The establishment of a common language between the engineer- ing, accessibility, and policy communities is an important first step in approaching a common challenge. This report hopes to provide this language. Content of This Report The basic outline of this report follows the sequence of study used by the team to conduct the research. After an ini- tial review of the literature and pre-existing knowledge base, the availability of actual treatments is discussed. This includes a process for narrowing down a long list of treatment alterna- tives to a succinct and well-targeted short list of solutions that maximize the efficiency of limited project resources. Following treatment identification, test sites were selected from a data- base of sites available for treatment installation. The geometry, traffic volumes, availability of resources (team and municipal), and team judgments based on experience were applied in deciding which locations should be used for treatment instal- lations. Field trials were conducted using a focused experimen- tal design approved by the Institutional Review Board (IRB) of Western Michigan University that used blind study partic- ipants at various locations. Field results were analyzed using a newly developed analysis framework that highlights the differ- ent aspects of the crossing task and allows for a targetâs appli- cation and evaluation of treatment effects. Finally, the results were interpreted and extended to other applications using sta- tistical modeling and discussion of simulation-based analysis approaches. The report is organized as follows: After the general intro- duction in this chapter, Chapter 2 gives an overview of the literature and background information on the question of pedestrian accessibility to complex intersections. Chapter 3 presents a methodology for identifying potential treatment solutions and discusses the data collection approach used in this research. It further presents the process used to select treatment sites and provides narrative descriptions of these locations. Chapter 4 presents an analysis framework for quan- tifying pedestrian accessibility. This framework guides the analysis in this document and is generally applicable to other studies. Chapter 5 presents the results of the field studies per- formed under the auspices of this project. Chapter 6 presents efforts to extend the field results to other locations and geome- tries through statistical modeling and simulation-based analy- sis approaches. Finally, Chapter 7 presents an interpretation of the results and conclusions of the research effort. The report further contains significant supplemental materials in sev- eral appendices. The reader is referred to this supplemental material directly from the discussion in the different chap- ters. In total, fourteen appendices are provided: ⢠Appendix A presents detailed analysis results for all field studies conducted through NCHRP Project 3-78A. ⢠Appendix B provides additional detail on the long list of treatments considered in this research. ⢠Appendix C provides results of the internal team treat- ment survey that was used to narrow the initial long list of treatments to a short list of treatments recommended for field testing. ⢠Appendix D gives details on site selection, including pho- tographs of other locations considered for this research. ⢠Appendix E presents details on treatment installations and further descriptions of the NCHRP Project 3-78A test sites. ⢠Appendix F gives specific details on the pedestrian hybrid beacon (PHB) installation at the two-lane roundabout in Golden, CO, including signal timing plans and other tim- ing details. ⢠Appendix G includes the blank participant survey forms used for participant questionnaires following each study. ⢠Appendix H presents details on a team-internal-conflict survey of crossing events at the CTL location intended to verify the viability of the orientation and mobility (O&M) intervention safety measure. ⢠Appendix I presents further details on the simulation analy- sis framework in the form of a paper presented by members of the research team. ⢠Appendix J presents details on development of the accessi- bility measures used in the analysis framework in the form of a paper presented by members of the research team. ⢠Appendix K presents details on the development of pedes- trian delay models in the form of a paper presented by members of the research team. ⢠Appendix L presents details on a simulation-based evalu- ation of roundabout signalization treatments in the form of a paper presented by members of the research team. ⢠Appendix M discusses the use of visualization techniques in NCHRP Project 3-78A in the form of a paper presented by members of the research team. ⢠Appendix N presents the completed and signed IRB approval forms for this research along with the blank consent forms signed by all participants. 12
