This manual provides instruction in the fundamentals of communications systems as they apply to traffic engineering and management. The subject matter encompasses networks, interconnecting trunks, and switching systems. The manual also introduces the principles of traffic engineering and management as they apply to military communications systems, including both circuit-switched and message-switched networks. Finally, the manual provides descriptions and step by-step instructions for traffic engineering and management of specific military communications systems for which the Army has responsibility. This manual includes the mathematical formulas and the traffic engineering tables and graphs which are required in traffic engineering processes.