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1 ABSTRACT 2 Previous studies have shown that roundabouts – especially multilane roundabouts - pose accessibility 3 challenges to pedestrians with vision impairments, in part due to a lack of yielding by drivers, especially on 4 multilane roundabout exit legs. In this study, three different treatments are assessed in terms of their 5 propensity for increasing driver yielding rate using a driving simulator. These are stop bar and crosswalk re-6 location away from the beginning of exit leg, and two types of beacons, namely a Pedestrian Hybrid Beacon 7 (PHB) and a Rectangular Rapid Flashing Beacon (RRFB). The study shows that installation of any kind of 8 beacon (PHB or RRFB) with or without crosswalk relocation increases driver yielding rates significantly. 9 Relocating the crosswalk does not provide a significant increase in driver yielding rate for the base case, but 10 appeared to further enhance the effectiveness of the PHB and RRFB treatments. The results of using an eye 11 tracker on drivers to track their gaze pattern while exiting the roundabout shows that having a beacon 12 installed with crosswalk relocation increases drivers’ attention both on the beacon and the pedestrian along 13 the road. However, a portion of participants failed to see and react to the pedestrian treatments, causing 14 concern about the visibility of these treatments at the roundabout exit leg. 15 INTRODUCTION 16 Several studies (1-4) have shown that roundabouts pose accessibility challenges for pedestrians who are 17 blind or visually impaired. Although geometric elements of a roundabout are designed to promote speed 18 reduction within the circle (5), drivers have higher speeds when they are exiting the roundabouts, compared 19 to when entering (4, 6). As a consequence, studies have shown that driver yielding rates to pedestrians 20 standing at the exit leg of roundabouts are lower compared to the entry (7). The purpose of this work is to 21 test the effect of different treatments aimed at increasing driver yielding rates to pedestrians at the exit leg of 22 roundabouts. The focus on the exit leg of two-lane roundabout is justified in an effort to focus study 23 resources on the crosswalk location that is documented to pose the greatest accessibility challenges (4, 6). 24 The paper is organized as follows. We first present the background and literature on pedestrian accessibility 25 to modern roundabouts, findings on drivers’ yielding process to the pedestrians, and the effects of potential 26 treatments on increasing driver yielding rate. The next section presents the objective of the research. The 27 methodology section describes the process for designing the driver simulation experiment, sample size 28 calculations, subject population attributes and challenges. Next, findings and results of driving simulator and 29 eye tracker data are discussed. We conclude by providing conclusions and recommendations for future work. 30 BACKGROUND AND LITERATURE REVIEW 31 Title II of Americans with Disabilities Act (ADA) requires that “ … new and altered facilities constructed 32 by, on behalf of, or for the use of state and local government entities be designed to be readily accessible to 33 and usable by people with disabilities (28 CFR 35.151)” (1). Various studies have shown that roundabouts 34 (multi-lane) are not readily accessible to visually impaired and blind pedestrians (2, 3). While design speeds 35 vary based on the geometric design, roundabouts are intended to promote speed reduction in the circulating 36 lanes. However, when exiting a roundabout, drivers are accelerating, thus reducing their propensity to yield 37 at the exit legs relative to entry (8). Geruschat and Hassan (6), among others, found drivers are more likely to 38 yield to pedestrians at the entry than exit. The results from NCHRP report 674 also indicate the probability 39 of a pedestrian encountering a yield is higher on the entry lane than on the exit lane, for one roundabout the 40 yielding rate for entry verses exit is 90% to 58% respectively.(4). 2 TRB 2012 Annual Meeting Paper revised from original submittal.
