Type of Problem Being Addressed
General Description of the Problem
The United States is aging-its older population will double over the next 30 years (Exhibit III-1). By 2030, one in five Americans will be 65 or older. As people age, a decline in sensory, cognitive, or physical function can make them less safe drivers, as well as more vulnerable to injury once in a crash. Yet older Americans depend on automobiles to meet their transportation needs. According to national transportation survey data, 90 percent of trips taken by older adults are by personal vehicle. Of that 90 percent, 70 percent involve the older adult driving the vehicle.
How safe are older drivers? The answer depends upon how “safety” is measured. On a licensed driver basis, older adults are among the safest on the road (Exhibit III-2). The average annual number of crashes in the United States is 68 per 1,000 licensed drivers, while the corresponding rate for drivers aged 65 and older is only 37. The picture changes somewhat when crash rates are calculated on the basis of miles traveled. Using this measure of exposure, older adults are at increased crash risk (Exhibit III-3). The increase in risk is evident for 65-74 year olds, but becomes even more pronounced with increased age. Drivers age 85 and older have about the same high crash rate per mile driven as 20-24 year olds.
The real safety concern for older drivers arises when one takes into consideration their increased likelihood of being injured or killed in a crash. Compared with an overall fatality rate of 2 per 1,000 crashes, persons ages 65-74 have a fatality rate of 3.2. For those 75-84, the rate is 5.3, and at 85 and above it climbs to 8.6. If instead of measuring safety in terms of crashes per licensed driver and crashes per mile traveled, one measures it in terms of fatalities per licensed driver and fatalities per mile traveled, there is clearly cause for concern (Exhibits III-4 and III-5). Both begin to increase by age 55, and the increase is especially dramatic for persons age 85 and older.
The real safety concern for the older driver arises when one takes into consideration their increased likelihood of being injured or killed once in a crash. Compared to an overall fatality rate of 2.0 per 1,000 crashes, persons ages 65–74 have a fatality rate of 3.2. For those ages 75-84, the rate is 5.3, and for those ages 85 and above it climbs to 8.6. If instead of measuring safety in terms of crashes per licensed driver and crashes per mile traveled, we measure it in terms of fatalities per licensed driver and fatalities per mile traveled, there is clearly cause for concern (Exhibit III-4 and Exhibit III-5). Both begin to increase by age 55, and the increase is especially dramatic for persons age 85 and older.
Taken together, the data suggest that the safety problem confronting older adults is as much an issue of crash survivability as it is crash avoidance. This safety problem is not likely to improve in the future without the highway safety community’s broad and concerted efforts.
Specific Attributes of the Problem
Studies have shown that compared with younger drivers, older drivers are more likely to be involved in crashes at intersections, especially when attempting a left-turn maneuver. Drivers 85 and older are more than 10 times as likely as 40-49 year olds to be in fatal multiple-vehicle crashes at intersections. Based on analysis of North Carolina crash data, older drivers are also over-represented in crashes involving right turns, U-turns, backing, starting in the roadway, and parking or leaving a parked position (Reinfurt et al., 2000). The fact that older drivers’ crashes are more likely to involve angle collisions and side impacts than other age groups are likely contributors to older drivers’ higher injury rates, despite the generally low speeds involved (Exhibit III-6).
About 55 percent of people age 85 and older who died in collisions died in angle collisions. This percentage is significantly lower for younger people. Only about 25 percent of people age 16-19 who died in collisions died in angle collisions.
While much attention has been given to older drivers’ higher frequency of intersection crashes, less attention has been given to their considerably lower frequency of single vehicle, run-off-roadway (ROR) crashes. Driving exposure may play an important role in both situations, since older drivers are more likely to crash at intersections and a greater proportion of their driving takes place in cities and on local streets. At the same time, older drivers may be less likely to run off the roadway, as they drive less on rural, two-lane roadways where these types of crashes typically occur.
The likelihood of being at fault in a crash has also been shown to increase with age: nearly 70 percent of drivers 75 and older involved in fatal two-vehicle crashes were at fault, compared with less than 40 percent for drivers 45-64 (Exhibit III-7). Specific crash types where older drivers are increasingly likely to be found at fault include angle collisions (usually involving two vehicles passing through an intersection on perpendicular paths), left and right turns across traffic collisions, and slowing or stopping collisions (Stewart et al., 1999). The fact that all of these collision types typically occur at intersections suggests that intersections pose problems for older drivers and that these problems do not stem merely from older drivers’ being more exposed to intersection situations.
As noted above, declining functional abilities may be responsible for older drivers’ increased risk of crashing. As people age, there is a decline in many of the abilities considered necessary to safely operate a motor vehicle. Older people, as a group, have reduced visual acuity, narrower visual fields, poorer nighttime vision, greater sensitivity to glare, slower reaction times, more attention deficits, reduced muscle strength, reduced flexibility and range of motion, and other declines in visual, cognitive, and psychomotor function that can adversely affect driving. Older people are also more likely to suffer from chronic medical conditions and to rely on medications, both of which can result in temporary or long-term functional losses. Exhibit III-8 identifies some of the key driving-related functional abilities that have been shown to decline with age.