The notion of transportation refers to the movement of people and goods across non-trivial geographical distances. Its history is as old as our civilization and its importance and scope are enormous, ranging from people walking on the earth's surface to carts and chariots driven by animals, automobiles, trains, airplanes and ships. To date, the discipline of transportation has experienced two major revolutions. Prior to the discovery of electromagnetic communication, information on the transport of goods and people was propagated along with the transported material and, in essence, their transit speeds were identical. The use of electromagnetic communication, the first major revolution in the discipline of transportation, made the propagation of information about the movement of goods and people significantly faster than the actual transport of the material at limited speeds. This resulted in superior planning as well as tracking of the movement of material through the transportation network. The availability of computing engines fuelled the second major revolution in transportation systems wherein fast and precise computers were exploited efficiently to control and coordinate the transport of goods and people across the system. For a number of reasons, including simplicity and the desire to maintain consistent control, the information and guidance providers of the transportation systems evolved as centralized units. A central control collected information about every entity within a specific transportation system and provided guidance and information to them as necessary. Today, the transportation discipline is on the brink of experiencing the third major revolution and possibly the most complex-the transformation from the centralized paradigm to the asynchronous, distributed paradigm which will integrate fast computers and high-performance computer networks through novel computer algorithms. This paper presents fundamental issues and principles underlying today's and tomorrow's intelligent transportation systems, including railways, highways, air travel, cargo networks and personalized rapid transportation systems. These principles have been utilized successfully in developing systems for railways and vehicles that have been reported in the literature. The paper also presents motivations for further research into the key areas of modelling and simulation and visualization of intelligent transportation systems.
