Architecture Reference for Cooperative and Intelligent Transportation

The communications view The physical view The functional view The enterprise view

ARC-IT 9.0 includes all views of the National ITS Reference Architecture - Enterprise, Functional, Physical and Communications views; as well as 150 service packages that present slices of the architecture to show how ITS could be deployed to solve real transportation needs. The Architecture Use section describes ways to apply the architecture in support of transportation planning and ITS project development.


September 2021 – Both RAD-IT and SET-IT have been updated with bug fixes and performance improvements. See below for details.


RAD-IT 9.0 adds new fields on the Start tab and new sort capabilities to the Interfaces and Comm tab. RAD-IT has been updated to correct known performance issues for project architectures and to support conversion from previous versions. Read more...


SET-IT 9.0 adds new fields on the Overview screen and a new Update Diagram tool. SET-IT has been updated to correct known issues and to support conversion from previous versions. Read more...


July 2021 – The Security / Device Class pages have been updated with new material based on a FHWA Vehicle to Infrastructure (V2I) Cybersecurity effort. This analysis of the V2I environment led to the selection of security controls that apply to Connected Vehicle Roadside Equipment, ITS Roadway Equipment, and all variations of Vehicle OBEs. Read more...



The Architecture Reference for Cooperative and Intelligent Transportation (ARC-IT) provides a common framework for planning, defining, and integrating intelligent transportation systems. It is a mature product that reflects the contributions of a broad cross-section of the ITS community (transportation practitioners, systems engineers, system developers, technology specialists, consultants, etc.).

ARC-IT is a reference architecture: it provides common basis for planners and engineers with differing concerns to conceive, design and implement systems using a common language as a basis for delivering ITS, but does not mandate any particular implementation. ARC-IT includes artifacts that answer concerns relevant to a large variety of stakeholders, and provides tools intended for transportation planners, regional architects and systems engineers to conceive of and develop regional architectures, and scope and develop projects.

To get started, begin with the menu bar above:

  • Architecture contains links to all of the content inside the architecture, and describes the structure of the architecture. In particular:
    • Service Packages represent slices of the architecture that address a specific service like traffic signal control and provide the most straightforward entry into ARC-IT content.
    • Views and its sub-menus provide view-specific content; if for example you are looking for a particular information flow, or a particular communications profile, browse the relevant physical and communications sections here.
    • Methodology and its sub-menus describe the structure of the architecture: how it is built, how the artifacts within are inter-related.
    • The Security section describes how security is addressed throughout the architecture and provides links to cross-cutting security content.
  • Architecture Use describes how to use ARC-IT, from the perspective of a regional architect, transportation planner or project systems engineer.
  • Architecture Resources provides access to all ARC-IT content in user-downloadable forms. Notably this also includes access to our tools: RAD-IT and SET-IT, that provide you with means to manipulate the architecture according to models' rules, customizing the reference architecture to your regional or project needs.
  • Architecture Terminology provides those definitions that permeate these pages.
  • Contact the Architecture Team gives you a direct line to the source. We want to hear from you! If you have questions, concerns or find an error (say it isn't so!) we'd like to know about it!