Analysis of Single-Lane Roundabout Slip Lanes Using SIDRA
Publication: Transportation and Development Institute Congress 2011: Integrated Transportation and Development for a Better Tomorrow
Abstract
Roundabout intersections, increasingly used in the U.S., sometimes incorporate slip lanes to facilitate right-turning traffic flow and reduce delay, thereby increasing capacity and safety. Performance of a single-lane roundabout with an adjacent slip lane is modeled with the SIDRA Intersection analysis tool for three types of slip lane: free-flow, yield, and stop, and is compared to having no slip lane. The gap acceptance-based assessment considers four experimental traffic percentage distribution matrices representing flow scenarios. SIDRA results confirm that average delay and circulating conflict volumes in a roundabout with a slip lane are related exponentially to slip lane volumes. A free-flow slip lane exit type helps to reduce total average delay in the roundabout and the slip lane approach. Both yield and stop slip lane exit types also reduce roundabout total average delay but to a lesser degree than a free-flow slip lane. Finally, theoretical capacity threshold values for slip lane volumes are estimated to range from 150 to 350 vehicles per hour for traffic volume distribution scenarios.
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© 2011 American Society of Civil Engineers.
History
Published online: Apr 26, 2012
ASCE Technical Topics:
- Flow (fluid dynamics)
- Fluid dynamics
- Fluid mechanics
- Free flow
- Highway and road management
- Highway transportation
- Highways and roads
- Hydrologic engineering
- Infrastructure
- Intersections
- Traffic analysis
- Traffic capacity
- Traffic delay
- Traffic engineering
- Traffic flow
- Traffic management
- Traffic safety
- Transportation engineering
- Water and water resources
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