Evaluation of the capacity of signalised two lane roundabouts

Taylor, Jarrod Lee (2012) Evaluation of the capacity of signalised two lane roundabouts. [USQ Project]

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Abstract

There has been ever increasing demand in the signalisation of roundabouts with the intention of improving the capacity and safety of the intersection. The signalisation may be
incorporated to reduce reliance on gap acceptance in heavily saturated conditions, control the dominance of a singular heavy leg demand, improve safety for cyclists and pedestrians or control all entry flows into the roundabout intersection.

This report evaluates the capacity of two lane signalised roundabouts under saturated conditions. Computer models were developed in LinSig and Excel to calculate the effective capacity of the intersections up to a level of service F. Models were developed based on differing variables such as inscribed diameters, queue discharge headways, phase sequences and signal cycle times. Relationships between the variables and the impact they had on the capacity of the signalised roundabout intersection were evaluated. The variables used in the capacity models were based on field research conducted under Australian driving conditions and research gathered from around the world. These models were then compared to unsignalised
capacities calculated from previous research across the world.

The conclusions from the project has found that a signalised roundabout using the standard phasing technique is a viable option in replacing an existing un-signalised roundabout that is failing to cater for capacities. This is compounded if the intersection has a high percentage of
right turn movements, pedestrian flows and is located in an urban environment. The installation of signals to an existing roundabout is deemed to be a cost effective solution in improving capacities.


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Item Type: USQ Project
Refereed: No
Item Status: Live Archive
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Agricultural, Civil and Environmental Engineering
Supervisors: Somasundaraswaran, Soma; Stafford, Ray
Date Deposited: 20 Feb 2013 06:04
Last Modified: 20 Feb 2013 06:13
Uncontrolled Keywords: roundabouts; singalised; intersection safety;
Fields of Research : 09 Engineering > 0905 Civil Engineering > 090507 Transport Engineering
URI: http://eprints.usq.edu.au/id/eprint/23039

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