Intersection Sight Distance Characteristics of Turbo Roundabouts

Journal Article (2021)
Authors

Akshay Salwan (Toronto Metropolitan University)

Said M. Easa (Toronto Metropolitan University)

Narayana Raju (Transport and Planning)

Shriniwas S. arkatkar ( Sardar Vallabhbhai National Institute of Technology)

Affiliation
Transport and Planning
Copyright
© 2021 Akshay Salwan, said easa, Narayana Raju, shriniwas arkatkar
To reference this document use:
https://doi.org/10.3390/designs5010016
More Info
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Publication Year
2021
Language
English
Copyright
© 2021 Akshay Salwan, said easa, Narayana Raju, shriniwas arkatkar
Affiliation
Transport and Planning
Issue number
1
Volume number
5
Pages (from-to)
1-18
DOI:
https://doi.org/10.3390/designs5010016
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Abstract

A turbo roundabout uses spiral circulatory roads for effectively counteracting the problems faced in modern multilane roundabouts. First developed in 1996, the turbo roundabout has an advantage over the conventional roundabout regarding capacity and safety. Turbo roundabouts are still in the developing phase in North America, but even in the European subcontinent where they exist in large numbers, reliable analytical studies on the critical parameters of roundabout visibility are lacking. Visibility (sight distance) helps to shape the geometry of the intersection and aids in safety. This paper presents the mathematical characteristics of the intersection geometry and intersection sight distance (ISD) of the turbo roundabout. Mathematical formulas are presented for the sight distance from the approaching vehicle to the conflicting-entering and circulating vehicles. The maximum lateral clearances to the conflicting vehicles are derived using mathematical optimization. The developed analytical method is verified graphically using AutoCAD. To assist in practical applications, design aids for the maximum lateral clearance are presented. The presented method and design aids should aid in promoting safety at turbo roundabouts.