A system has an architecture.
Stakeholders have interests in the system.
Stakeholders have concerns.
Architecture viewpoints frame concerns, and architecture views address those concerns.
These are the framing concepts behind an architecture and its structure. Interested and budding systems engineers are encouraged to peruse ISO/IEC/IEEE 42010 for the conceptual foundations of system architecture description. ARC-IT, like the CVRIA and National ITS Architecture before it, leveraged stakeholder engagement, both directly and indirectly through the examination of published ITS-related documents (Concepts of Operation, System Requirements, Standards etc.) to provide the basis for architecture concepts.
The architecture forms the basis for a common language definition of both established (legacy) ITS and early C-ITS or connected vehicle deployment concepts. ARC-IT is a reference architecture: it provides the basis for regional and local implementation. Implementers are expected to customize the architecture to their own needs: first by creating a regional architecture describing the long term vision of their region of interest, then defining projects within that regional architecture, and finally by developing detailed project system architectures. ARC-IT's associated tool set provides the tools enabling these activities: RAD-IT provides regional architecture development and project architecture definition functions, while SET-IT takes those project definitions and enables the creation of design-level artifacts.
ARC-IT is a singular architecture composed of four viewpoints: Physical, Functional, Communications and Enterprise. These viewpoints frame the concerns held by ARC-IT stakeholders. The viewpoints are modeled in the form of various diagrams, tables and associated databases. Viewpoints are related through various correspondence rules, and may need to be considered together depending on the user's task. For instance, those interested in regional planning are probably most concerned with content in the physical and enterprise views, while those concerned with project implementation would need to also consider the communications view.