This lecture introduces the course with an example of the evacuation Walcheren in case of flooding and a short introduction to network traffic flow fundamentals. Traffic congestion phenomena, fundamental diagrams, capacity drop, wide moving jams, pedestrian flow congestion and shockwave theory are shortly introduced. Different traffic flow modeling approaches such as microscopic and macroscopic modeling are discussed in this lecture. Different example applications of theory and models will be discussed. This lecture also provides the course scope and overview.  Different traffic flow variables such as time headway, distance headway, traffic intensity, traffic density, local mean speed, instantaneous mean speed are introduced in this lecture.