Resumen
In Japan, some traffic event is displayed by the graphic symbol with letters on expressway VMS. However, drivers are difficult to comprehend some of them. In order to solve the current situation, we investigated the referent characteristics based on the idea that the suitable referent was needed for the graphic symbol to transmit the message appropriately. We searched for the systematic grasping method using the semantic distance about the concept of road information and the relation among concepts through drivers? analogizing images related event names as a referent. Through these processes, in order to establish the referent of a graphic symbol, we showed that it was possible to systematize with arranging the causal relationship in the context, and that it is important to grasp structurally the causal relationship of the information related traffic event.