Traffic Circulation Efficiency of Elliptical Roundabouts

Hardi S. Fathullah; Hirsh M. Majid; Chro H. Ahmed; Sulleyman H. Sourkan; Karzan S. Ismael; Balen Z.  Abdulsamad

doi:10.14500/aro.11150

Hardi S. Fathullah 1 Department of Engineering, Kurdistan Institution for Strategic Studies and Scientific Researches, Sulaimani, 46001, Kurdistan Region – F.R. Iraq https://orcid.org/0000-0002-1114-7417
Hirsh M. Majid Department of Civil Engineering, College of Engineering, University of Sulaimani, Sulaimani, Kurdistan Region – F.R. Iraq https://orcid.org/0000-0002-4225-9788
Chro H. Ahmed Department of Civil Engineering, College of Engineering, University of Sulaimani, Sulaimani, Kurdistan Region – F.R. Iraq https://orcid.org/0000-0002-6371-6888
Sulleyman H. Sourkan Sulaimani Polytechnic University - Digital Cultural Heritage Research Group, Kurdistan Region – F.R. Iraq https://orcid.org/0000-0002-4356-6253
Karzan S. Ismael Department of City Planning Engineering, Technical College of Engineering, Sulaimani Polytechnic University, Kurdistan Region – F.R. Iraq https://orcid.org/0000-0002-3735-6225
Balen Z. Abdulsamad Department of Geotechnical Engineering, Faculty of Engineering, Koya University, Koya KOY45, Kurdistan Region – F.R. Iraq https://orcid.org/0000-0002-5656-9947

Keywords: Circular roundabout, Elliptical roundabout, Heavy vehicle percentage, Performance evaluation, Traffic simulation

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.

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Author Biographies

Hardi S. Fathullah, 1 Department of Engineering, Kurdistan Institution for Strategic Studies and Scientific Researches, Sulaimani, 46001, Kurdistan Region – F.R. Iraq

Hardi S.Fathullah is a Lecturer and researcher at the Kurdistan Institution for Strategic Studies and Scientific Research. He got a B.Sc. degree in Civil Engineering/Building Construction and M.Eng. degree in Civil-Transportation and Highway Engineering. His research interests are; Traffic Simulation, Transportation Planning, Pavement Evaluation, and Transport facility operational performance evaluation. Hardi is a member of the Kurdistan Engineer's Union.

Hirsh M. Majid, Department of Civil Engineering, College of Engineering, University of Sulaimani, Sulaimani, Kurdistan Region – F.R. Iraq

Hirsh M. Majid is an Assistant Prof. at the Department of Civil Engineering, College of Engineering, Sulaimani University. He got the B.Sc. degree in Building and Construction Engineering, the M.Sc. degree in Highway Engineering and the Ph.D. degree in Computer and Control Engineering. His research interests are in intelligent transportation system (ITS), traffic control system, traffic management, and transportation planning. Dr. Hirsh is a consultant member of Kurdistan Engineers Union.

Chro H. Ahmed, Department of Civil Engineering, College of Engineering, University of Sulaimani, Sulaimani, Kurdistan Region – F.R. Iraq

Chro H Ahmed is an Assistant Prof. at the Department of Civil Engineering, College of Engineering, Sulaimani University. She got the B.Sc. degree in Building Construction Engineering, the M.Sc. degree in Highway Engineering and the Ph.D. degree in Transportation Engineering. Her research interests are in Transportation Planning, Traffic Impact Analysis and Traffic Management. Dr. Ahmed is a consultant member of Kurdistan Engineers Union.

Sulleyman H. Sourkan, Sulaimani Polytechnic University - Digital Cultural Heritage Research Group, Kurdistan Region – F.R. Iraq

Sulleymam H. Sourkan is a Lecturer at the Department of Energy and Petroleum Engineering, College of Engineering, Sulaimania Polytechnic University. I got the B.Eng. Degree in Civil Engineering, the M.Sc. Degree in Structural Engineering. My future research interests are in Civil and Structural Engineering in General and Concrete Design in Specific. I am “Sulleyman Sourkan” a member of IStructE.

Karzan S. Ismael, Department of City Planning Engineering, Technical College of Engineering, Sulaimani Polytechnic University, Kurdistan Region – F.R. Iraq

Karzan S. Ismael is a Lecturer at the Department of City Planning Engineering, Technical College of Engineering, Sulaimani Polytechnic University (SPU). He got a B.Sc. degree in Engineering Urban Planning at SPU, an M.Sc. degree in Transport Engineering and Planning at the University of Salford/ Manchester-UK and currently pursuing a Ph.D. degree in Transportation Engineering and Vehicle Engineering at Budapest University of Technology and Economics, Hungary. His research interests are in urban and transport planning, travel behaviour analysis and emerging transport. Mr. Karzan has been an active and excellent reviewer for several reputable journals in Elsevier, Springer, IEEE and MDPI.

Balen Z. Abdulsamad, Department of Geotechnical Engineering, Faculty of Engineering, Koya University, Koya KOY45, Kurdistan Region – F.R. Iraq

Balen Z. Abdulsamad is a Lecturer at the Department of Geotechnical Engineering, Faculty of Engineering, Koya University. He got the B.Sc. degree in Geotechnical Engineering, the M.Sc. degree in Infrastructural engineering of transport and geotechnics. His research interests are in Road pavement, Infrastructure development and using waste material to improve subgrade layers. Mr. Balen is a member of American Concrete Institute.

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