Toward Roundabout Accessibility—Exploring the Operational Impact of Pedestrian Signalization Options at Modern Roundabouts
Publication: Journal of Transportation Engineering
Volume 134, Issue 6
Abstract
This paper explores the use of pedestrian signalization options for crosswalks at one- and two-lane roundabouts to enable these facilities to be accessible to pedestrians with vision impairments. Motivated by uncertainties about the safety of roundabouts for blind pedestrians, audible pedestrian signals hold promise for safely regulating the interaction of vehicles and pedestrians at these facilities. However, the use of pedestrian signals at roundabouts is controversial because of the potential for queue spillback into the circulating lane and delays to vehicular traffic. The objective of this work is to quantify pedestrian-induced delays and queuing impacts of a pedestrian signal placed at the busiest approach of a modern roundabout. The analysis is performed using a calibrated microsimulation model and includes assessment of innovative solutions for crossing geometry and phasing scheme at one-lane and two-lane roundabouts. The results suggest that the impact of pedestrian signals at roundabouts is greatest as vehicle volumes approach capacity, but that vehicle delay and queuing can be mitigated through innovative signal configurations. The findings are important in light of recent discourse concerning the accessibility of roundabouts to pedestrians with vision impairments that may ultimately move towards a requirement for signalization for certain facility types.
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Acknowledgments
The research leading up to this document was supported by NCHRP 3-78a, “Crossing solutions at roundabouts and channelized turn lanes for pedestrians with visual disabilities.” The opinions expressed in this paper are that of the writers and do not necessarily reflect the opinion of the National Academies of Sciences. The writers would like to thank the National Academies for the opportunity to be involved in the project and for permission to share these results with the transportation research community. They would also like to thank the members of the project panel, who have provided continuous feedback to the research efforts. They are also indebted to the other members of the project team, who have been invaluable in discussing the application of microsimulation models to the project. Finally, the writers would like to thank the NCHRP 3-65 project team for providing operational data and video recordings of the two roundabouts.
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Information & Authors
Information
Published In
Journal of Transportation Engineering
Volume 134 • Issue 6 • June 2008
Pages: 262 - 271
Copyright
© 2008 ASCE.
History
Received: May 22, 2007
Accepted: Nov 5, 2007
Published online: Jun 1, 2008
Published in print: Jun 2008
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