The objective of this research was to develop and confirm the validity of a simulation model incorporating fuzzy logic that could be used in analyzing the mechanism involved in the occurrence of accidents in right turns. This model is applicable to accidents occurring at intersections in which a vehicle making a right turn collides with an oncoming vehicle traveling straight ahead. Such accidents can be traced to driver error stemming from ambiguous recognition and judgment. The model is capable of analyzing separately and quantitatively each factor involved in the mechanism causing such accidents. It can be also used to evaluate the risk involved in the execution of right turns. It was noted that older drivers tend to underestimate the speed of oncoming cars. Right turn simulations were conducted with the model reflected this recognition characteristic. The results of the simulations revealed that for older drivers the time allowance for executing a right turn was shorter by a maximum of 1.0 second in comparison with younger drivers. In addition, evaluations were also made for oncoming cars and motorcycles and for differences in the perception of oncoming vehicle speeds and the perception of distance under daytime and nighttime driving conditions.