Driving Ability Index: an instrument for assessing elderly people’s performance

Aging causes the decline of driving related skills, so accident rates are higher for older drivers. However, being able to use the car motivates older people to maintain an active life and participate in social activities. When deprived of their driving licence, the elderly often suffer from isolation and depression so this phenomenon also has social implications. For these reasons it is necessary to recognize drivers who are potentially risky, because they no longer have the skills required to drive, from those who are still able to drive and be independent. The aim of this study is to develop an easy to manage tool for objectively evaluating the driving ability of elderly drivers, for identifying the premature signs of any decline in physical ability and cognitive skills and for identifying devices best suited to help them to overcome their deficits and to improve their driving abilities and stay safe behind the wheel for longer. Driving Ability Index (DAI) questionnaire has been proposed (Meloni, 2014) in order to evaluate ability to drive into four quality levels: excellent, good, moderate and poor. With the aim to verify the effectiveness of the Driving Ability Index, road tests and simulator tests were conducted, and the driving performances have been evaluated. In the study 31 drivers have been involved in the on road study and 12 drivers have been involved in the simulator tests. The performances obtained in both tests (on-road test and simulator) have been compared with the scores obtained in the questionnaire, through Kendall’s tau c test. This analysis shows that only for women the level of driving ability estimated by the questionnaire reflects their real driving ability. This result may be due to the greater capacity to self-evaluate that women have, they sometimes tend to underestimate their abilities, in fact they do not renew their licence when they are still able to drive safely, and in the questionnaire there are many questions that require self-evaluation, both in general and in relation to their physical and cognitive abilities. So in order to predict driving ability in elderly people and to identify the most significant variables in the DAI questionnaire, a factorial analysis and a linear regression have been performed. The relation proposed is simple to apply and requires a limited amount of input information (five variables), so it may be used when renewing driving licences to identify elderly people with poor driving skills, who may put others and themselves at risk every time they get behind the wheel. And it also identifies drivers with moderate driving ability and therefore still able to drive, though with some difficulty. These drivers could benefit from in-vehicle assistance systems, which are suitable for the compensating for the deficits (indicated in section 3 of the questionnaire).