Abstract
This paper describes a longitudinal study on elderly drivers car-following behavior. Field experiments in which the elderly drivers participated using AIST instrumented vehicles were conducted twice, in 2003 (call “first experiments”) and in 2008 (call “second experiments”). AIST instrumented vehicles were equipped with various sensors and a driving recorder system for measuring the vehicle velocity and for detecting the relative distances and speeds to leading and following vehicles. The driving behavior data of non-elderly drivers were collected by the same procedures as the elderly drivers. We compared the time headways to leading and following vehicles of the elderly and non-elderly participants determined in the first experiments with those determined in the second experiments. The results suggested that the time headway to the leading vehicle was longer in the second experiments than in the first experiments. This tendency was found in the elderly participants, but was not found in the non-elderly participants. The time headway to the following vehicle in the second experiments was similar to that in the first experiments, indicating no differences in traffic flow on the analyzed road. The longer time headway to the lead vehicle implies a compensatory behavior of elderly drivers due to agerelated functional changes. We finally investigated the influences of age-related declines of cognitive and physical functions on the longitudinal changes of the car-following behavior using a questionnaire on self-awareness changes in cognitive and physical functions while driving. The results reveal that the ability to assess traffic conditions influences the elderly drivers compensatory behavior when following a leading vehicle.
Keywords: elderly driver, car following behavior, instrumented vehicle, longitudinal study, cognitive aging