Contribution of the IATSS research projects to disseminating modern roundabouts in Japan.

Until early 2000s, modern roundabouts (RABs) were poorly understood in Japan and were not fully recognized as a form of at-grade intersections. The RAB research projects of the International Association of Traffic and Safety Sciences (IATSS), which began in 2009, started with examining the applicability of RABs in Japan and have steadily progressed to various stages of field experiments, social implementation, and dissemination promotion activities. These RAB research projects, which lasted for approximately seven years, are considered to have played a significant role in the practical application of RAB in Japan. This paper provides a chronological overview of the history, content, and development status of these projects and records and discusses the role that IATSS research projects played in the early days of RABs in Japan. • Triggers for breakthroughs at modern roundabouts in Japan • Chronological overview of the history and content of the IATSS roundabout projects • Archive from applicability examinations and field experiments to practical deployment. [ABSTRACT FROM AUTHOR]