Design Guidelines For Turbo Roundabout Based on Intersection Sight Distance to Circulating Conflicting Vehicle

Turbo Roundabout is a roundabout provided with spiral circulatory roadways for effectively counteracting the problems of modern multilane roundabout. This roundabout has an edge over modern roundabouts regarding capacity and safety and was first developed by Professor Fortujin in 1996.Turbo roundabouts are present in large percentage in Europe and is still in developing phase in North-America. Although in all the guidelines nothing has been mentioned about one important parameter of roundabout i.e. visibility. Visibility or Sight distance helps us to shape the geometry of intersection and aids in safety. In this paper sight distance analysis is going to be analysed on turbo roundabouts with a focus on Intersection Sight Distance to circulating conflicting vehicle. The traditional graphical approach has been supplemented with the analytical solution consisting of derivation of generalized mathematical equations for intersection sight distance for conflicting circulating vehicle at turbo roundabout.