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.
Get full access to this article
View all available purchase options and get full access to this article.
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.
References
Akcelik, R., and Troutbeck, R. (1991). “Implementation of the Australian roundabout analysis method in SIDRA.” Highway capacity and level of service, Brannolte, ed., Balkema, Rotterdam, The Netherlands, 17–33.
Ashmead, D., Guth, D., Wall, R., Long, R., and Ponchillia, P. (2005). “Street crossing by sighted and blind pedestrians at a modern roundabout,” J. Transp. Eng., 131(11), 812–821.
Federal Highway Administration (FHwA). (2000). Roundabouts: An informational guide, FHWA-RD-00-067, Turner Fairbank Highway Research Center, McLean, Va.
Federal Highway Administration (FHwA). (2003). Manual of uniform traffic control devices (MUTCD), McLean, Va., ⟨http://mutcd.fhwa.dot.gov/⟩ (April 12, 2007 ).
Guth, D., Ashmead, D., Long, R., Wall, R., and Ponchillia, P. (2005). “Blind and sighted pedestrians’ judgments of gaps in traffic at roundabouts.” Hum. Factors, Summer 2005, 47(2), 314–331 (AN 18006375).
Inman, V., and Davis, G. (2007). “Synthesis of literature relevant to roundabout signalization to provide pedestrian access.” Final Rep., FHwA, McLean, Va., ⟨http://www.access-board.gov/research/roundabouts-signals/report.pdf⟩ (April 30, 2007 ).
Kittelson and Associates. (2008). “Roundabout/traffic circle inventory database.” Portland, Ore., ⟨http://roundabouts.kittelson.com/InvMain.asp⟩ (March 31, 2008 ).
Mahmassani, H., and Sheffi, Y. (1981). “Using gap sequences to estimate gap acceptance functions.” Transp. Res., Part B: Methodol., 15B, 143–148.
National Cooperative Highway Research Program (NCHRP). (2006). “Project 3-65: Applying roundabouts in the United States.” Kittelson and Associates Inc., Washington, D.C., ⟨http://www4.nationalacademies.org⟩ (July 26, 2006 ).
National Cooperative Highway Research Program (NCHRP). (2007). “Roundabouts in the United States. Rep. No. 572, Transportation Research Board, Washington, D.C.
National Cooperative Highway Research Program (NCHRP). (2008). “Project 3-78. Crossing solutions at roundabouts and channelized turn lanes for pedestrians with vision disabilities.” Institute of Transportation Research and Education, Raleigh, N.C., ⟨http://www4.nationalacademies.org⟩ (July 26, 2006 ).
PTV. (2005). VISSIM 4.10 user's manual, Karlsruhe, Germany.
Rouphail, N., Hughes, R., and Chae, K. (2005). “Exploratory simulation of pedestrian crossings at roundabouts.” J. Transp. Eng., 131(3), 211–218.
Schroeder, B., and Rouphail, N. (2007). “A framework for evaluating pedestrian-vehicle interaction at unsignalized crossing facilities in a microscopic modeling environment.” Proc., 86th Annual Meeting of the Transportation Research Board, Washington, D.C., Transportation Research Board, in press.
Tucson DOT. (2006). Pedestrian traffic signal operations, City of Tucson Department of Transportation, ⟨http://dot.ci.tucson.az.us/traffic/tspedestrian.cfm⟩ (July 31, 2006 ).
U.S. Access Board. (2005). Revised draft guidelines for accessible public rights-of-way, ⟨http://www.access-board.gov/prowac/draft.htm⟩ (July 29, 2006 ).
Wall, R., Long, R., Guth, D., Ashmead, D., and Ponchillia, P. (2005). “Roundabouts: Problems of and strategies for access.” Int. Congress Series, Sep 2005, 1282, 1085–1088 (AN 18745105).
Information & Authors
Information
Published In
Copyright
© 2008 ASCE.
History
Received: May 22, 2007
Accepted: Nov 5, 2007
Published online: Jun 1, 2008
Published in print: Jun 2008
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.