ADVANTEC was selected by LA Metro to update the Los Angeles County Regional Intelligent Transportation Systems (ITS) Architecture. This essential planning tool fosters coordination among over 90 stakeholders, including cities, Caltrans, ports, transit agencies, and emergency responders. Originally developed in 2004, the architecture serves as a framework for promoting interoperability, guiding ITS project planning, and supporting integration across jurisdictional boundaries. With advancements in connected vehicle (CV) and automated vehicle (AV) technologies, LA County's leadership in Smart City initiatives, and a growing focus on non-motorized mobility, the update modernizes the architecture using ARC-IT and integrates elements of the Connected Vehicle Reference Implementation Architecture (CVRIA). ADVANTEC’s update addresses long-standing deficiencies, aligns with regional sustainability policies, and supports future CV/AV deployments. Additionally, it will develop a user-friendly website to make the architecture accessible for planning, design, and procurement. This project re-establishes the Regional ITS Architecture as a living resource that supports the next generation of transportation innovation in LA County.