As part of FTA’s effort to promote continuous safety improvement in the public transit industry, these Guidelines for Performing Rail Transit Agency Accident Investigations were developed to provide rail transit agencies leading transit industry practices for performing investigations. The supporting Rail Transit Accident Investigations—Background Research provides a comprehensive examination of each SMS element to broaden the reader’s understanding of how each component complements the others. The recommended practices described in this document and emphasized through the background research are not intended to be prescriptive in nature. Each public transit agency is responsible for tailoring its event investigation processes to its unique operating environment, the complexity of the operation, and the transit modes provided. These locally-developed processes should correspond to a transit agency’s existing Standard Operating Procedures (SOPs) or emergency plan.