A joint research team from Toyohashi University of Technology, Department of Architecture and Civil Engineering, Toyota Transportation Research Institute, and Daido University has established a method to represent driving behaviors and their changes that differ among drivers in a single statistical model, taking into account the effect of various external factors such as road structure. This method was applied to measure the effectiveness of Intelligent Speed Adaptation (ISA), which controls excessive speed violations. As a result, the research team found that in some cases, it is effective for drivers with a high tendency of frequent excessive speeding, and in other cases, effective only for elderly drivers depending on the style of the ISA. This method can be applied not only to ISA but also to measure the effectiveness of traffic safety management technologies that encourage drivers to change their various driving behaviors.