This report examines the effects of age on the driving habits of the elderly, using the 1990 Nationwide Personal Transportation Survey (NPTS). Elderly is defined as persons 65 years or older. Six aspects are considered: the amount of daily driving exposure, driving by time of day, driving speed, driving by type of roadways, vehicle size and the number of passengers carried. The scope of analysis is limited to the content of the 1991 NPTS and those aspects of driving habits that are hypothesized to have safety implications for the elderly. The scale of analysis is limited to urban residents. Regression is used to isolate the effects of being elderly while holding constant a set of personal, household, and location characteristics of the drivers, as well as a set of trip characteristics. Elderly drivers show an increased effort of self-protection in their driving habits relative to mid-aged drivers (persons between the ages of 25 and 64 years). Being elderly not only makes elderly drivers reduce daily driving exposure, avoid driving at night, avoid driving during peak hours, and avoid driving on limited-access highways, but also make them drive at lower speeds, drive larger automobiles, and carry fewer passengers. Despite their effort of selfprotection, however, the elderly still show a higher risk of crash and injury per unit of exposure than the mid-aged. If policies induce the elderly to further adjust their driving habits to offset the external risks of ther driving, their risk of crash and injury would be reduced and society as a whole would be better off. The elderly, however, are likely to be worse off as a consequence of reduced mobility. The challenge to policy-makeing is to balance these consequences of any policy concerning the mobility and traffic safety of the elderly. (A)
Abstract