Comparative analysis of four new alternative types of roundabouts: “Turbo”, “flower”, “target” and “four-flyover” roundabout

Abstract

Analysis of literature shows that “modern roundabouts” nowadays exist in all European countries, as well as in more than 60 countries elsewhere in the world. Nowadays, a growing number of studies, presented in scientific and professional literature, point out a poor traffic safety characteristics of “standard” two-lane roundabouts and lower capacity then was expected. These problems are resolved in more ways in different countries; however the solution, whereby the number of conflict spots is diminished has proven to be the most successful. Lower number of conflict spots is one of characteristics of the alternative types of roundabouts. The alternative types of roundabouts are usually more recent and implemented only in certain countries. It is typical for them that they differ from “standard” one- and two-lane roundabouts in one or more design elements, while the purpose of their implementation is also specific. This paper illustrate four relative new alternative types of roundabouts - “turbo”, “flower”, “target” and “four flyover” roundabouts and their comparison from designing, capacity and traffic - safety point of view.