This project was conducted to provide an objective measure of the relationship between older adults’ scores on a set of driving assessment tools and their (serious point) violations and crashes over a period of 18 months following the assessments. An additional objective was to compare alternative methods of measuring driver exposure. The assessments were performed on 692 participants age 70 and older who visited one of four Maryland Motor Vehicle Administration (MVA) field offices between September 2008 and June 2009, under NHTSA contract DTNH22-05-D-05043, Task Order 10. The assessments emphasized cognitive performance domains, specifically visuospatial ability, speed of (visual information) processing, divided attention, visual search, working memory, and response planning or “executive function.” Contrast sensitivity was also measured, as well as simple and choice brake reaction time. The functional assessments examined in this research were computer-based and designed to be self-administered, although the assistance of a test administrator was always available and was required for some measures. Univariate and multivariate analyses examined the relationships between functional assessment scores and safety indicators. The measure of “executive function” (maze performance) was highlighted as a significant predictor of crash risk in the study results. This may be of interest to occupational therapy/driving rehabilitation providers as a potentially valuable tool to support clinical evaluations of fitness to drive; and, to developers of screening tools for early warning of driving impairments, and of products meant to educate older drivers and their families about age-related changes that impact safe driving. A subsample of 10 drivers participated in a naturalistic study, driving their own cars for a 1-month period with instrumentation installed by the research team. Data collected included the date and time of each trip taken, monitored via the vehicle’s OBD-II port; self-reported driving habits obtained via a Driving Preferences Instrument (DPI); and the date, time, and other characteristics for each trip as recorded using a paper-and-pencil trip log. The results showed a very strong (r > 0.90), significant correlation between trip log entries and OBD data; whereas DPI responses, that relied on memory and estimation, were only weakly correlated with the objective OBD record, and included both over- and under-reporting of driving exposure. These results reinforce a growing concern about the reliability of self-reported exposure data in traffic safety research. (Author/publisher)
Abstract