Design of the First Italian Roundabout with Jointed Plain Concrete Pavement

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.

Risk Analysis and Safer Layout Design Solutions for Bicycles in Four-Leg Urban Intersections

“…The counter-clockwise circulation forces bicyclists to reduce their dispersion of paths, lengthens their trajectories, and provides drivers with more reaction time. Indeed, this layout enables the collection and distribution of all bicyclists that access and egress the intersection, from the different legs, on the same trajectory [25]. In order to obtain the three-phase signal system of L7 and L8, we added a third phase dedicated to bicyclists' movements.…”

Jointed Plain Concrete Pavements in Airports: Structural–Economic Evaluation and Proposal for a Catalogue

“…The large experience of the IAF has helped to collect data on design, construction, and maintenance of runways over more than 80 years. With regard to concrete pavements, Jointed Plain Concrete Pavements (JPCP) without dowel and tie bars are the most frequent solution because of simple and rapid execution, lower cost than other concrete solutions (the presence of bars involves an increase in expenditure varying from 8% to 20%, while a continuous reinforcement involves a higher initial expense of 50% or more) [6], good monitored performances [7][8][9][10][11], and simple maintenance works [12,13], the latter with potential applications to other facilities, where regular maintenance might lag behind [14][15][16]. The absence of reinforcement requires a double foundation layer: a bottom one composed of a granular mixture and a top one composed of a cement-stabilized mixture.…”