The FTA’s State Safety Oversight (SSO) regulation establishes definitions and minimum notification thresholds for safety events. The SSO final rule defines a “safety event” and requires a rail transit agency (RTA) to notify its State Safety Oversight Agency (SSOA) and the FTA within two hours of any safety event that meets certain thresholds. This Two-Hour Notification Guide is designed to help RTAs identify those events and notify FTA. This document updates prior guidance, issued on September 24, 2021, to incorporate the changes adopted in FTA’s SSO final rule, which published on October 18, 2024.