Route guidance in vehicular roadways has become an important and emerging method of congestion alleviation. The proliferation of low cost electronics such as sensors, wireless communication, and computing equipment has now made large scale vehicle navigation practical. The advanced computational equipment available has made performing complex algorithms in real time possible, the key to the operation of vehicle route guidance systems. While route guidance systems fundamentally strive for similar optimum operation, several important differences exist in the design of these systems. This paper presents an investigation of some of the main distinctions between these systems. Much work has been done in this field in the past, which is presented here as a classification and comparison of such systems