###### Abstract  
This work presents the results of the overall design of the first Italian roundabout with jointed plain concrete pavement. The examined case study complies with current international standards and practices for geometry of roundabouts and road pavements. The construction of a concrete pavement in an urban roundabout will better manage and slow down fast vehicular flows, and increase traffic fluidity in an important junction, trafficked by heavy vehicles, where maintenance works should be reduced to avoid queues. The design of the roundabout involved several competences for: defining the geometry of the four-arm junction, designing the thickness of the jointed plain concrete pavement both on the circular crown and the arms, studying the mix design of a high resistance concrete. As regard to the pavement, the result of the study was an un-dowelled concrete pavement composed of square slabs laid on a cement concrete subbase and a granular layer. The shape of the slabs has been designed to optimize the structural performance of their material, which is a high strength concrete mix derived from an extensive laboratory test work. In general, the results summarized approaches typical of different design conditions: urban ones for traffic flow and safety needs; high-traffic ones for the chosen pavement type; airport ones for the absence of dowel and tie bars at the joints. Indeed, the article has highlighted that the design process of a concrete roundabout requires multiple analyses to consider various features and correctly re-design an existing urban junction. Its geometrical design, the structural design of the concrete pavement and the theoretical and experimental design of the concrete mix were the main phases of this process and they needed different competences to conduct comprehensive and appropriate analyses. roundabout; concrete; jointed plain concrete pavement pacs: **10.10. A remarkable advantage of roundabouts is increasing safety for vehicles using the intersection by reducing the fatal crashes and all crashes by a significant percentage [8; 9]. In the USA a study on 23 intersections estimated highly significant reductions of 40% for all crash severities combined and 80% for all injury crashes [10]. Similar reductions were found in some studied performed all over Europe [11; 12]. The design process of a roundabout requires the definition of its geometric characteristics according to the expected traffic demand and the layouts defined by the reference standards. There are many ways to classify a roundabout: according to the yield pattern, its approach lanes, design speed, etc. The typology proposed by the U.S. Federal Highway Administration (FHWA) [13] is maybe the most complete, since it is based on the statement that \"a roundabout is a type of a circular intersection, but not all circular intersections can be classified as roundabouts\". FHWA detects the following types of circular intersection:  
* Roundabouts: circular intersections with specific features as yield control of entering traffic, channelized approaches, appropriate geometric curvature;
* Rotaries: old-style circular intersections, typical of USA roads up to the '60 s, with a large diameter (even > 100 m), and where circulating traffic yields to entering traffic;
* Signalized traffic circle: old-style circular intersections, used in some cities of the USA where traffic signals are used to control one or more entry-circulating point. * Neighborhood traffic circles at intersections of local streets for traffic calming or \"aesthetics\" reasons. FHWA separates the roundabouts into three basic categories according to size and number of lanes:  
1. Mini roundabouts: small roundabouts in low speed urban areas with average operating speed of 50 km/h or less, useful in environments with right of way constraints or with insufficient right of way for compact roundabouts
2.