Due to their evident benefits roundabouts are widespread among the congested urban road networks. The primary aims of the roundabouts are to improve safety, traffic and environmental conditions, which derive from their proper design. Vehicle swept path analysis is considered a crucial parameter in the design of a roundabout. The accurate prediction of the vehicle's movement ensures a safe route and identifies the conflict areas, at the entry, exit and along the circulatory roadway especially in a 2-lane roundabout where accidents are over-represented. The purpose of this paper is to investigate vehicle's turning path in 2-lane roundabouts. The large trucks are of particular interest, because they demand more space in their motion. Consequently, the dimensions of the roundabouts are determined by the turning paths of the heavy vehicles and buses. Therefore, in order to perform swept path analysis, the turning paths of different type of large vehicles in roundabouts with different diameter have to be computed. Moreover, the overlap of the turning paths of two vehicles traveling simultaneously in a two- lane roundabout will be investigated. In the recent years, roundabouts have also become increasingly popular in Greece. In fact, in the city of Volos four roundabouts have been constructed in the last two years. The two of them have been chosen to be investigated in terms of geometry and safety based on the preceding analysis.
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