International overview of roundabout design practices and insights for improvement of the Italian standard

Abstract

Roundabouts are hastily spreading around the world, mainly because of their good safety performance, and several countries have recently updated their standards and guidelines. However, inconsistencies in design standards and practices are observed. In this paper, a critical review of the Australasian, EU, and US standards and guidelines is performed. As a result, key issues of the existing standards are identified, along with research areas to fill the knowledge gaps and recommendations for improvement in a case study, Italy. These recommendations are mainly based on the concepts of design flexibility and performance based design. Indeed, rigid standards, which do not really take into account safety and operational consequences of the design decisions and the need to balance opposing demands, might produce undesirable outcomes.