Abstract
This paper describes a method for evaluating the effectiveness of the route guidance system, which provides a driver with individual information to accomplish a trip under such objectives as the travel time saving, the fuel saving, the reduced air pollution and the reduced traffic accident etc.. In this paper the travel time saving is chosen as an evaluation criterion of this system. The travel time indicates the time required from a driver's specific origin (O) to his specific destination (D). Multiple routes may be chosen with each specific O-D, owing to his route choice criteria and to his trial and error. The route choice probability is defined, based on a traffic study of a driver's comprehension of road configuration. On the other hand, the travel time along the selected route is affected by the vehicular type, the traffic flow, the traffic regulation, the traffic signal and the weather etc.. In this paper the travel time is defined in terms of a conditional probability density function. The characteristics of the function are examined by a traffic study of travel time using an improved license matching technique.
The probability density function of the travel time in the case of the specific O-D is composed of the route choice probability and the conditional probability density functions, mentioned above. Comparing the probability density function of a guided vehicle with that of a non-guided vehicle, a mathematical formula to calculate the amount of travel time saving is derived.
