MODERN SUBURBAN ROUNDABOUTS IN CROATIA – FLOWER AND TURBO ROUNDABOUTS

Turboroundabouts are specially designed multilane roundabouts with spiral circulatory roadway and physically separated traffic lanes. This roundabout layout was developed in the late nineties of the last century with the aim of increasing the traffic safety and capacity at classic multi-lane roundabouts. However, the experience has shown that turbo roundabouts have certain deficiencies – due to its complex geometry and large outer diameters, the reconstruction of existing less safe multi-lane roundabouts into turbo roundabouts is financially very demanding. In that case, a construction of so called flower roundabout is much better solution. Namely, unlike in the case of turbo roundabouts, it is possible to adjust the existing multi-lane roundabouts into flower roundabouts without moving any of the outer road curbs. Within the scope of this study, geometric design and performances of these two modern roundabout types are analyzed. Their advantages and disadvantages in regard to performances of classic multi-lane roundabouts are discussed, examples from Croatian design practice are presented, and recommendations for their planning and designing are provided.

Authors

  • Tamara Dzambas
  • Vesna Dragcevic
  • Dominik Benci

Keywords

  • comparison
  • flower roundabout
  • geometry
  • performances
  • suburban roundabouts
  • turbo roundabout