Evaluation of Older Driver Fitness-to-Drive Metrics and Driving Risk Using Naturalistic Driving Study Data

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Date
2015-07-28
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Volume Title
Publisher
National Surface Transportation Safety Center for Excellence
Abstract

In this study, we evaluated the relationship between older drivers’ fitness assessment profiles and their driving risk, represented primarily by crash and near-crash (CNC) rate, and secondarily by high g-force (HGF) event rate, all recorded during a naturalistic study of senior drivers. Due to the relatively small sample size in this pilot investigation (20 primary drivers), principal component analysis was used for dimension reduction and classification of the 60 total fitness profile metrics. Negative binomial regression models were employed to model the CNC and HGF events. The results indicated that contrast sensitivity measures were significantly associated with CNC rate. The greater the sensitivity, the lower the CNC rate, as would be the expected nature of that association. In the HGF event analysis, we found that CNC rate was positively related to HGF rate. The fitness metric contrast sensitivity was also related to HGF event rate. In addition, two metrics related to metacognition, a measurement of one’s perception of one’s own cognitive status, were associated with HGF event rate. Higher HGF rates were associated with greater self-rating of cognitive status as well as greater disparities between that same self-rating and an objective metric of cognitive status. The results of this study provide crucial information on the metrics and protocols which could be applied by motor vehicle departments, physicians, occupational therapists, Certified Driving Rehabilitation Specialists, and others for whom determining seniors’ fitness to drive is an important component of their work. Further, these results can be further investigated and validated using the much larger database of senior driver data collected in the Second Strategic Highway Research Program (SHRP 2) Naturalistic Driving Study.

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Keywords
Fitness-to-drive, Older drivers, Crash risk, naturalistic driving studies
Citation