Crash risk of older female drivers

Monash University Accident Research Centre - Report #245 [2005]

Authors: J. Oxley, J. Charlton, B. Fildes, S. Koppel, J. Scully, M. Congiu & K. Moore

Full report in .pdf format [2.6MB]

Abstract

The majority of the elderly in the population are women and future predictions suggest an increase in this proportion, an increase in the proportion of licensed older women, increased driving by older women drivers, and a subsequent estimated three-fold increase in crash rates in the coming decades without active intervention. It is therefore essential to understand the contributory factors to crash and injury risk in order to develop appropriate and effective countermeasures to reduce this risk.
Two studies are described in this report that aimed to address the crash risk of older female drivers and to determine the contributory factors. The first study used existing data from a recent survey of 673 current older female drivers in the ACT. The survey provided a rich data source in which to examine the relationships between health and driving factors and crash risk. Logistic regression analysis was used to model the ‘at-risk’ older female driver using crash involvement in the last five years as the dependent variable and taking correlations between other variables into account. The second case-control study of 48 crash-involved and 44 non crash-involved older female current drivers in the ACT examined in detail the effect of functional performance, health factors and driving factors on crash risk. Functional performance was examined using four validated tests of skills that are likely to be important in driving such as visual processing, memory and search, scanning strategies, attention span, divided and selective attention, problem-solving, and motor performance.
The survey data analyses revealed that the most ‘at-risk’ older female drivers were those who: i) were the principal driver, ii) were moderately or not at all confident that they were a safe driver; iii) shared driving on long-distance trips; iv) had problems with the driving style of older drivers; and, v) experienced problems driving on unfamiliar roads.
The case-control study confirmed the findings of the survey data analyses and identified a number of additional predictors of crash involvement. Poor attentional, cognitive, executive and motor skills as well presence of multiple medical conditions were associated with crash involvement. In particular, the results suggested that those with more pronounced functional changes and multiple medical conditions were most at risk of crashing possibly due to the effect of functional limitations on the skills necessary for driving performance but also due to the effects on adoption of compensatory strategies. Low confidence, difficulty in some driving situations and principal driver status were also related to increased risk of crash involvement. These findings suggest that older female drivers who become principal drivers, perhaps due to illness or death of a partner, may lack the up-to-date driving experience and associated confidence to drive safely. Further, the findings suggest that this group may be at risk of crash involvement as a result of ‘low mileage’ and a higher propensity to drive on the urban network. The finding that the majority of crash-involved participants were involved in crashes at intersections would support this view.
This information has enhanced our understanding of which drivers are at increased risk, particularly through identifying a small, more precisely defined target group for road safety countermeasures. Recommendations for countermeasures were made and include behaviour and educational resources, improvements to licensing procedures, and improvements to road design and system operation. Recommendations for further research were also made.

Sponsoring organisation - NRMA-ACT Road Safety Trust