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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/10200

Title: Left turn accommodation at unsignalized t-intersections: a case study in Kumasi using VISSIM modelling
Authors: Nyame-Baafi, Eric
Issue Date: 23-Jan-2017
Abstract: The most common type of intersection improvement considered in Ghana is signalization. However, other actions such as the installation of left-turn lanes (left-turn accommodation) have been proven to improve the efficiency and safety of an intersection without the need for signalization in the short term. Warrants which guide the installation of such lanes in Ghana are adopted from elsewhere and as a result do not reflect local traffic flow conditions. This study investigated the use of VISSIM micro simulation tool to establish volume warrants based on a delay threshold to guide the installation of left-turn lanes at unsignalized Tintersections. The VISSIM model was calibrated using traffic flow, delay, average and maximum queue length data obtained from a two-hour video recording of the case study intersection during the morning peak period. After calibration, several scenarios covering a wide range of operational conditions were simulated. Using Level of Service (LOS) C cut off point of 25 s/veh as the maximum acceptable delay to minor road left-turning traffic, an equation has been developed which predicts the threshold minor road left-turn volume above which a minor road left-turn lane may be considered and below which a minor road l eft-turn lane may not be necessary for a range of major road volumes. The critical delay to major road left-turning traffic was found to be 16 s/veh. Major road left-turn lane volume warrants were determined based on this threshold delay value. The approach used in this study can serve as a procedure guide that can be used by metropolitan and municipal road engineers to assess the need for left-turn lanes.
Description: A thesis submitted to the Department of Civil Engineering, College of Engineering, in partial fulfilment of the Requirements for the degree of Master of Science Road and Transportation Engineering, 2016
URI: http://hdl.handle.net/123456789/10200
Appears in Collections:College of Engineering

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