Transportation Technology Center, Inc. (TTCI), through a program sponsored by the Federal Railroad Administration (FRA), developed the architecture and core requirements for a Positive Train Control (PTC) Track Database Auditing System (TDAS), including system, subsystem, and interface requirements that can be used to develop and test prototype solutions in future phases of the program. TDAS aims to support the development of specifications, in the form of standards and/or best practices, for subsystems of an auditing system designed to support flexible implementation and increased automation of auditing functions.