Geometric Characteristics of Roundabouts with Offset and Skewed Approaches
Publication: Journal of Transportation Engineering, Part A: Systems
Volume 149, Issue 7
Abstract
Roundabouts are a superior solution to traffic operation issues at intersections with complex geometry, such as skewed and offset approaches where there are property constraints or where realigning approaches is costly. Although roundabouts with offset, skewed approaches are unavoidable, the current design standards are typically established based on standard roundabouts having radial approach alignments and perpendicular approaches. This work aimed to (1) examine the geometric characteristics of roundabouts with offset or skewed approaches or both, (2) establish the relationships of the design parameters with the approach offset and angle, (3) develop geometric optimization models, and (4) recommend geometric design guidelines for inscribed circle radius, entry curve radius, and exit curve radius. The approach or intersection angle ranges are also recommended for single-lane and two-lane roundabouts under urban and rural conditions. Design graphs and tables of the minimum required radii were developed. They not only help highway designers and engineers to select the appropriate parameters and reduce trial-and-error efforts during design, but also offer a guide to property needs during the planning stage.
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Data Availability Statement
Some or all data, models, or codes that support the findings of this study are available from the corresponding author upon reasonable request.
Acknowledgments
The authors are grateful to three anonymous reviewers for their thorough and helpful comments. This research was financially supported by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada.
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© 2023 American Society of Civil Engineers.
History
Received: Aug 1, 2022
Accepted: Mar 1, 2023
Published online: May 12, 2023
Published in print: Jul 1, 2023
Discussion open until: Oct 12, 2023
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