The document provides an introduction to highway engineering, including definitions and classifications of transportation systems and highways. It discusses the history of road development from ancient footpaths to modern paved highways. It also provides an overview of the development of roads in Ethiopia, from early trails to the current network of over 100,000 km of roads, including the construction of expressways. The classifications of highways are described according to factors such as ownership, surface type, design, traffic volume, location, and the Ethiopian Roads Authority system.