Traffic Circulation Efficiency of Elliptical Roundabouts

Fathullah, Hardi S. and Majid, Hirsh M. and Ahmed, Chro H. and Sourkan, Sulleyman H. and Ismael, Karzan S. and Abdulsamad, Balen Z. (2023) Traffic Circulation Efficiency of Elliptical Roundabouts. ARO-THE SCIENTIFIC JOURNAL OF KOYA UNIVERSITY, 11 (2). pp. 65-72. ISSN 2410-9355

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Abstract

This paper investigates the impact of geometry of central island of roundabout on operational performance in terms of delay and capacity measures. A roundabout with an elliptical central island having major and minor axes of 63 and 44m respectively was selected as a case study. Using SIDRA Intersection software two simulation models are developed while considering two geometric shapes of central island; one with an elliptical shape and the other with a circular shape. The peak traffic volume of each approach was assigned to both models as a preliminary simulation then twelve scenarios were generated by assigning identical lane volumes starting from a value that gave level of service A and increasing gradually to level of service F. In each scenario 100% of the volume assigned to an approach while the other was assigned with 75% of it and this process was reversed for every run. The results revealed that at high degree of saturation, the elliptical roundabout generally possessed a higher performance especially in term of delay and capacity compared to the circular roundabout. Furthermore, a parametric study was carried out through running eight more simulation scenarios to examine the impacts of heavy vehicle percentage (HV%) on the roundabout operational performance. The (HV %) started from 2% and increased to 12% with alternate approach virtual volume, and the results showed that performance of the elliptical roundabout was higher than the circular roundabout. However it was more susceptible to increase of HV% in term of control delay and capacity.

Item Type:	Article
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Uncontrolled Keywords:	Circular roundabout, Elliptical roundabout, Heavy vehicle percentage, Performance evaluation, Traffic simulation
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Divisions:	ARO-The Scientific Journal of Koya University > VOL 11, NO 2 (2023)
Depositing User:	Dr Salah Ismaeel Yahya
Date Deposited:	25 Sep 2023 09:45
Last Modified:	25 Sep 2023 09:45
URI:	http://eprints.koyauniversity.org/id/eprint/410

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