TRAFFIC SIGN TAXONOMIES IN COOPERATIVE, CONNECTED, AND AUTOMATED MOBILITY ENVIRONMENTS

Abstract

The progressive deployment of automated driving and connected vehicle technologies within modern transportation systems has intensified the need for consistent and machine-interpretable representations of roadside traffic signage. Within the framework of Cooperative, Connected, and Automated Mobility (CCAM) and its implementation through Cooperative Intelligent Transport Systems (C-ITS), traffic signage functions not only as a physical roadside infrastructure element but also as a structured information source supporting infrastructure–vehicle interaction. Advancement of vehicle automation questions adequacy of existing conventional traffic sign taxonomies and classification schemes. This narrative review focuses on taxonomies related to roadside traffic signage in the context of automated driving and connected vehicles. It synthesizes existing approaches to traffic sign classification, semantic structuring, and functional categorization as discussed across scientific, industrial, and regulatory literature over the past decade. Based on review findings, areas of convergence and divergence among proposed traffic signage taxonomies, as well as conceptual gaps affecting interoperability between vehicle systems and roadside infrastructure, are presented. The analysis indicates that, while technological capabilities for automated and connected mobility continue to evolve, the development of harmonized and future-oriented traffic signage taxonomies remains fragmented. The paper outlines current research directions and highlights open issues that may point the way of evolution of classification frameworks for traffic signage toward unification within cooperative and automated transportation systems.