An Operation and Safety Assessment Study of Roundabout Types

회전교차로 형태별 운영 및 안전성 평가에 관한 연구

Jang, Ki-Hun;Lee, Sang Soo

  • Received : 2015.08.31
  • Accepted : 2015.10.01
  • Published : 2015.10.15


PURPOSES: The aim of this study is to analyze and compare the operational effectiveness and safety of three different types of roundabout found in the literatures using a VISSIM and SSAM program. METHODS : The three types roundabout tested are the 2-lane roundabout (2R), the Turbo roundabout (TR), and the Flower roundabout (FR). For each scenario, three roundabout types and traffic conditions such as traffic volume and movement ratio were applied to VISSIM in order to compute the average delays. In addition the total conflict was calculated through SSAM by using trajectory data from VISSIM. RESULTS: From the analysis results, the average delay in TR and FR type was higher than the 2R. Regardless of the roundabout types, the average delay was reduced as the right-turn vehicles increased. The total conflict in TR was fewer than 2R for all traffic conditions. CONCLUSIONS : The results of this study can be used in the planning and design process of roundabout deployment. The data also provides some numerical justifications in transition from at-grade intersection to roundabout.


Conflict;Delay;SSAM;Turbo-Roundabout;Flower Roundabout


  1. Bared, J.G., Afshar, A.M., Using Simulation to Plan Capacity Models by Lane for Two- and Three-Lane Roundabouts, Transportation Research Record, Vol. 2096, pp. 8-15, 2009.
  2. Corriere, F., Guerrieri, M., Performance Analysis of Basic turbo-Roundabouts in Urban Context, Procedia-Social and Behavioral Sciences, Vol. 53, pp. 622-632, 2011.
  3. Engelsman, J.C., Uken, M., Turbo Roundabouts as An alternative to Two Lane Roundabouts, The 26th Annual Southern African Transport Conference 9, pp. 581-589, 2007.
  4. Flannery, A., Geometric Design and Safety Aspects of Roundabouts, Transportation Research Record, Vol.1751, pp. 76-81, 2001.
  5. Fortuijn, L. G, Turbo Roundabouts Design Principles and Safety Performance, Transportation Research Record, Vol. 2096, pp. 16-24, 2009.
  6. Isebrands, H., Crash Analysis of Roundabouts at high-Speed Rural Intersection, Transportation Research Record, Vol. 2096, pp. 1-7, 2009.
  7. Majed N. Al-Ghandour, Schroeder, B.J., Williams, B.M., Rasdorf, W.J., Conflict Models for Single-Lane Roundabout Slip Lanes from Microsimulation, Transportation Research Record, Vol. 2236, pp. 92-101, 2011.
  8. Mauro, R., Branco, F., Comparative Analysis of Compact Multilane Roundabouts and Turbo-Roundabouts, Jounal of Transportation Engineering, Vol. 136, Issue 4, pp. 316-322, 2010.
  9. Ministry of Land, Infrastructure and Transport, Korean Roundabout Design Guideline, 2010.
  10. Saccomanno F. F., Flavio Cunto, Giuseppe Guido, and Alessandro Vitale, Comparing Safety at Signalized Intersections and Roundabouts Using Simulated Rear-End Conflicts, Transportation Research Record, Vol.2078, pp. 90-95, 2008.
  11. Song K. S., Evaluation and Application of Turbo Roundabout as an Alternative to Two-lane Roundabouts, Ajou University, Master's thesis, 2011.
  12. The Minister of Land, Infrastructure and Transport, Korea Highway Capacity Manual, 2013.
  13. Tollazzi, T., Rencelj, M., Turnsek, S., New Type of Roundabout : Roundabout with "Depressed" Lanes For Right Turning - "Flower Roundabout", Promet - Traffic&Transportation, Vol.23, No.5, pp. 353-358, 2011.
  14. Transportation Research Board, NCHRP Report - 572 : Roundabouts in the United States, 2007.
  15. TRB, Highway Capacity Manual, National Research Council, Washington D.C., TRB, 2010
  16. Vasconcelos, L., Seco, A.B.A., Safety analysis of turbo-roundabouts using the SSAM technique, CITTA 6th Annual Conference on Planning Research, pp. 1-15, 2013.
  17. Yin, D., Qiu, T.Z., Comparison of Macroscopic and Microscopic Simulation Models in Modern Roundabout Analysis, Transportation Research Record, Vol. 2265, pp. 244-252, 2011.


Supported by : 한국연구재단