Toward Roundabout Accessibility—Exploring the Operational Impact of Pedestrian Signalization Options at Modern Roundabouts

Schroeder, Bastian J; Rouphail, Nagui M.; Hughes, Ronald G.

doi:10.1061/(asce)0733-947x(2008)134:6(262)

Cited by 21 publications

(19 citation statements)

References 5 publications

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“…In fact, relocating the PHB from 20 to 60 feet increased yielding from 68.3% to 85.6% (p-value =0.00010), and relocating the RRFB from 20 to 60 feet resulted in an increase from 51.7% to 73.9% (p-value =0.00001). The combined effects of higher yielding at an increased off-set distance is an important finding, especially since higher off-set distances have previously been linked by research to improved operational performance for vehicles (22), resulting in lower pedestrian-induced impacts on vehicular delay over the standard crosswalk location.…”

Section: Resultsmentioning

confidence: 99%

Simulator Study of Driver Responses to Pedestrian Treatments at Multilane Roundabouts

Salamati

Schroeder

Rouphail

et al. 2012

Transportation Research Record: Journal of the Transportation R

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Previous studies have shown that roundabouts – especially multilane roundabouts - pose accessibility challenges to pedestrians with vision impairments, in part due to a lack of yielding by drivers, especially on multilane roundabout exit legs. In this study, three different treatments are assessed in terms of their propensity for increasing driver yielding rate using a driving simulator. These are stop bar and crosswalk relocation away from the beginning of exit leg, and two types of beacons, namely a Pedestrian Hybrid Beacon (PHB) and a Rectangular Rapid Flashing Beacon (RRFB). The study shows that installation of any kind of beacon (PHB or RRFB) with or without crosswalk relocation increases driver yielding rates significantly. Relocating the crosswalk does not provide a significant increase in driver yielding rate for the base case, but appeared to further enhance the effectiveness of the PHB and RRFB treatments. The results of using an eye tracker on drivers to track their gaze pattern while exiting the roundabout shows that having a beacon installed with crosswalk relocation increases drivers’ attention both on the beacon and the pedestrian along the road. However, a portion of participants failed to see and react to the pedestrian treatments, causing concern about the visibility of these treatments at the roundabout exit leg.

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Section: Resultsmentioning

confidence: 99%

Simulator Study of Driver Responses to Pedestrian Treatments at Multilane Roundabouts

Salamati

Schroeder

Rouphail

et al. 2012

Transportation Research Record: Journal of the Transportation R

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“…With more vehicular arrivals, each pedestrian signal activation produces a more powerful impact on vehicle delays and increases the possibility that yielding queues at entry points will spill back into the circulatory lane(s) (19,20). Second, the likelihood of queue spillback can be diminished by shifting the crosswalk segment on the outbound lane(s) farther away from the circulatory lane(s) (19,20). Since vehicle delay is directly proportional to the display length of the red interval, it was hypothesized that signalization with a shortened red display would reduce vehicle delay.…”

Section: Study Objectivesmentioning

confidence: 99%

“…VISSIM, a microsimulation program, is applied worldwide to model diverse transportation facilities because of its multimodal modeling capability, adequate detector function, self-customizable traffic control algorithm via vehicle-actuated programming, and convenient run-time control interface for external object-oriented programs (21). VISSIM models have been found effective, valid, and credible for traffic studies regarding roundabouts, freeways, urban networks, crosswalks, intersections, and arterials (18)(19)(20)(22)(23)(24)(25). It can mimic vehicle-yielding behaviors at roundabout entries, and its link-connector structure is flexible in modeling unique geometrics.…”

Section: Study Environmentmentioning

confidence: 99%

“…Rouphail et al found the introduction of a pedestrian-actuated (PA) signal adds delay to visually impaired pedestrians compared with sighted pedestrians who cross at unsignalized splitter islands (18). Schroeder et al investigated two signal alternatives at single-and double-lane roundabouts to make these facilities accessible to the visually impaired (19). Simulation results show the impact of signalization was maximized under oversaturated conditions, but vehicle delay and the queuing effect can be alleviated through an innovative signal.…”

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confidence: 99%

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Simulation Study of Access Management at Modern Roundabouts: Treatments of Pedestrian Crosswalks

Guan

Noyce

2011

Transportation Research Record: Journal of the Transportation R

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The widespread emergence of modern roundabouts in North America has kindled a controversy about pedestrian access. Almost uninterrupted traffic streams, ambient noises, and urban settings make it difficult for the visually impaired to perceive safe crossing gaps when only auditory cues are used. In 2005, the U.S. Access Board released a revised draft guideline calling for the provision of a “pedestrian-activated traffic signal … for each segment of the crosswalk” to ensure access for vision-impaired pedestrians. The Access Management Manual prescribes major transportation actions encompassing multimodal streets with sidewalks and adequate pedestrian refuges, but the manual does not address the issue of pedestrian access at roundabouts. In North America few roundabouts have been outfitted with pedestrian signals. Little research has explored signalizing roundabouts for pedestrian access improvements. This simulation study quantitatively assessed the performance of four pedestrian signals placed at roundabouts with a wide spectrum of test scenarios resulting from varied crosswalk layouts, installation schemes, and operational conditions. A two-stage installation scheme was found more operationally efficient than a one-stage scheme; with the two-stage scheme, no significant differences existed between three layouts. When a one-stage scheme operated, a distant layout reduced vehicle delay and queue length because of enlarged storage space. High-intensity activated crosswalk signals induced minimum vehicle delay, and pedestrian user-friendly interface signals minimized pedestrian delay while fully protecting pedestrians. The findings provide an objective basis for identifying crosswalk treatments to improve roundabout accessibility and are informative for transportation policy makers, planners, and practitioners in the access management community who work at enhancing roundabout accessibility for pedestrians.

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“…Previous studies on roundabouts are mainly based on single-lane and double-lane roundabouts. There is much literature concerning safety [4][5][6][7][8][9][10][11][12][13], operational analysis [14][15][16][17][18][19][20][21] and environmental impacts [22][23][24][25]. By contrast, very few publications are devoted to developing new-style traffic control solutions.…”

Section: Introductionmentioning

confidence: 99%

Multi‐level traffic control at large four‐leg roundabouts

Zhang

2016

J of Advced Transportation

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Summary Yield control and full signalization are typical traffic control solutions that can be used at large roundabouts. In the face of increasing congestion issues, it is preferred to use yield control during off‐peak periods and full signalization during peak periods. To automatically accommodate time‐varying vehicular demands, a multi‐level traffic control (MTC) is developed to implement hybrid yield control and fully actuated control at large four‐leg roundabouts. With new application of traffic control devices and traffic detection system, the right‐of‐way can be assigned to entering and circulating vehicles in three modes. The ‘all entering’ mode is equivalent to a yield control. The ‘no entering’ and ‘concurrent entering’ modes are equivalent to a fully actuated control. On the basis of time headways and occupancy times that are detected on the entry and circulatory roadways, the mode of right‐of‐way assignment can be changed in response to actual traffic conditions. For a specific mode of right‐of‐way assignment, traffic signal operation is managed by some detectable traffic events that are happening. The results of the simulation experiments conducted by VISSIM indicated that: (i) MTC was stabilized at the ‘all entering’ mode during off‐peak periods and at the ‘concurrent entering’ mode during peak periods; (ii) MTC would typically change the mode of right‐of‐way assignment according to actual traffic conditions as vehicular demands increased from off‐peak to peak or decreased from peak to off‐peak; and (iii) statistically speaking, MTC inherited the operational advantages of yield control and fully actuated control, and could be effective in improving the operational performance of large four‐leg roundabouts for all hours of the day, regardless of the level of left‐turn ratios. Copyright © 2016 John Wiley & Sons, Ltd.

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Toward Roundabout Accessibility—Exploring the Operational Impact of Pedestrian Signalization Options at Modern Roundabouts

Cited by 21 publications

References 5 publications

Simulator Study of Driver Responses to Pedestrian Treatments at Multilane Roundabouts

Simulator Study of Driver Responses to Pedestrian Treatments at Multilane Roundabouts

Simulation Study of Access Management at Modern Roundabouts: Treatments of Pedestrian Crosswalks

Multi‐level traffic control at large four‐leg roundabouts

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