Traffic engineering is essential for designing efficient transportation systems. Explain the principles of traffic flow theory, including traffic volume, density, and speed. Discuss the factors influencing traffic flow, such as roadway geometry, traffic control devices, and driver behavior, highlighting their impact on traffic operations and safety. Additionally, describe the methods used in traffic engineering, such as traffic impact studies, capacity analysis, and traffic simulation models, emphasizing the importance of data$-$driven decision$-$making in optimizing transportation systems.