Abstract

The existing Stopping Sight Distance (SSD) and Decision Sight Distance (DSD) design methods for roundabouts are deterministic. This means that all of the design variables are predetermined, fixed values. This study presents a probabilistic method for the determination of SSD and DSD at roundabouts based on the equation recommended by the American Association of State Highway and Transportation Officials (AASHTO 2011). The reliability-based method considers all design parameters as random variables. Three types of SSD (SSD for approaches, SSD along the circulatory lane, and SSD for exiting vehicles to the pedestrian crosswalk) were considered in this study. DSD was considered for roundabout approaches. The First-Order Second-Moment and Advanced First-Order Second-Moment methods were used to model SSD and DSD. Once the required SSD and DSD were determined, the lateral clearance requirements at every point of the roundabout were calculated.

Highlights

  • AUTHOR’S DECLARATION I hereby declare that I am the sole author of this thesis

  • This study presents a probabilistic method for the determination of Stopping Sight Distance (SSD) and Decision Sight Distance (DSD) at roundabouts based on the equation recommended by the American Association of State Highway and Transportation Officials (AASHTO 2011)

  • In reality, all design variables are random variables and some are correlated with one another, there is a need to calculate stopping and decision sight distance values based on the randomness of the design variables

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Summary

Introduction

AUTHOR’S DECLARATION I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I authorize Ryerson University to lend this thesis to other institutions or individuals for scholarly research. I further authorize Ryerson University to reproduce this thesis by photocopying or by other means, in total or in part, at the request of other institutions or individuals for the purpose of scholarly research. The existing Stopping Sight Distance (SSD) and Decision Sight Distance (DSD) design methods for roundabouts are deterministic. This means that all of the design variables are predetermined, fixed values. I would like to thank Dr Kaamran Rahimifar and Dr Essam Dabbour for their helpful suggestions. Circular intersections were less favorable due to traffic delays and major safety concerns. Safety and traffic delays are two major problems associated with traffic circles

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