The basic concepts in the transportation and traffic operations field that should be understood by every transportation professional are presented here in a thorough, coherent, and self-contained way. Introductory chapters on "tools" cover topics such as graphical methods, optimization, probability, stochastic processes, statistics and simulation; these are complemented by application chapters on traffic dynamics, control, observation, and scheduled modes, where the fundamental ideas are presented in depth. A key element of the author's approach is that only that material is presented which is definitely known and correct. At the same time, an effort has been made to point out various pitfalls and common errors so that they can be avoided. The result is an invaluable source of reliable, well grounded and clearly explained ideas, tools and techniques for the transportation professional.