Summer 2003
Featured Article

The Freedom of the Open Road: Driving and Older Adults

By A. James McKnight

The traffic safety community, as well as the public at large, has long recognized that older adults are at elevated risk of being killed or injured in a motor vehicle crash. The exhortation to "get the old folks off the road" is frequently heard, particularly after a well-publicized incident in which a superannuated driver is clearly at fault.

This concern for the risks that older drivers face--and pose--is magnified by the anticipation that their numbers will increase over the coming decades. As a result of longer life spans and the aging of the baby boom generation, the proportion of Americans age 65 and older is expected to increase by some 60 percent by the year 2030. Also anticipated is an increase in the proportion of this age group who are still driving. Though only two thirds of women age 65 and older are currently licensed, more than 90 percent of the women who will be 65 or older in 2030 now hold driver's licenses. Since women live longer than men, this change will have a disproportionate effect upon the percentage of older adults who are still driving: It is estimated that in 2030 close to 90 percent of adults age 65 and older will be drivers. The combination of these two demographic shifts will lead to an estimated total increase of more than 130 percent in the number of older drivers in the United States (Organization for Economic Cooperation and Development [OECD], 2001).

Is the choice still safety versus independence?

While concern over older-driver safety issues remains high, in recent years concerns over the mobility of older adults also have increased. In particular, the current generation of elders has lived primarily in suburban areas and has been dependent upon the automobile for the satisfaction of its daily transportation needs. Efforts to reduce accident exposure by imposing driving restrictions on older adults have been increasingly tempered by concern for the price that is paid in loss of mobility, a trend facilitated to some extent by the ideas of the community of activists lobbying for people with disabilities. These activists have questioned the choice of safety over independence in design of services and other programs. The two goals of safety and mobility, traditionally seen in social services as antagonistic, now are being blended into a single goal of providing safe mobility for elders and others with mobility difficulties. Agencies concerned with the welfare of older adults have begun to include transportation assistance among their services. This assistance includes efforts to help those with driving problems find ways of overcoming such problems or limiting their effects on driving, as well as efforts to find alternatives to driving. Nevertheless, the risk that older drivers pose to the public will rise over the coming years as their numbers on the highways increase.

Accident Risk of Older Drivers

However, older drivers are not quite the menace to society that public opinion suggests. Their high fatality and injury rates result more from their fragility than from their unsafe driving practices. Older drivers and passengers are far more likely to be killed or injured in an accident than their younger counterparts: The likelihood of being fatally injured at age 70 is more than twice the risk of adults ages 20-50 who are involved in accidents; 80-year-olds are four times more likely than younger accident victims to be fatally injured (Mitchell, 2000). Their per-mile crash rate for noninjury accidents is no greater than that of drivers in the 20-to-24-year-old age group (NHTSA, 2000).

Furthermore, when accidents are analyzed in terms of culpability, older drivers are as likely to be the victims as the driver at fault (Dulisse, 1997). What appears statistically as a progressive rise in per-mile accident likelihood with age is not a universal change within the population as a whole, but rather, an increase in the small proportion of the age cohort who experience the declines that create increased risk. Even among the 75-and-older age group, the majority of drivers present no greater threat to themselves or the public than they ever did.

In summary, although older drivers are significantly more likely to be the victims of accidents causing injury or fatality, their threat to the motoring public at large is no greater than that of any other age group. To the extent that they are at risk, the risk is primarily to themselves.

Unsafe Driving Practices Among Older Adults

Further, without knowing the degree to which drivers in various age groups are exposed to situations calling for specific actions, estimates of risk are only relative. The fact that older drivers have more of their accidents in certain situations may mean that they face those situations more often than do younger drivers rather than that they are more likely to respond in an unsafe way.

Much of the research into the problems of older drivers involves assumptions as to the effect of various physiological declines upon risk rather than any demonstrated relation of those declines to accidents. In many instances, drivers compensate for their deficiencies in ways that prevent them from increasing their risk.

An abundance of research shows that intersections are a relatively greater source of difficulty for older drivers than for younger cohorts. Staplin and colleagues (1998) conducted an extensive review of research on intersection problems encountered by older drivers; it revealed that older drivers are over-represented in accidents involving left turns across traffic, even with some control for exposure (that is, the frequency with which drivers encounter the situation). Other intersection accidents result from acceptance of unsafe gaps between cars in traffic, violations of traffic signals, and stops for no apparent reason. While research shows that virtually all aspects of driving may pose difficulties for older drivers, the most frequent are those performances that involve sharing attention, judging gaps in traffic, visual search, navigation, and motor control.

Attention sharing. Attention-sharing deficiencies show up most often in left turns, where drivers must divide attention between oncoming traffic and vehicular as well as pedestrian traffic on the left side of the vehicle. Crossing an intersection without signals requires sharing attention between cars from each direction. Often drivers will look in both directions, see a car coming from one direction, wait until it passes, and then pull out without a look back in the other direction. Similarly, much of failure to comply with traffic controls such as red lights and stop, one-way, or lane-use signs can be attributed to failure to notice them when attending to traffic and other route signs. Attention sharing becomes a particular challenge for elders traveling in unfamiliar areas, where destination-finding actions compete with operation of the vehicle. Cell phones are a particular distraction for older drivers. Older drivers often resolve the conflict created by inability to attend to different demands on attention or sources of danger by slowing down or stopping, which itself can become a danger.

Judgment about traffic gaps. Deficiencies in the ability to judge gaps in traffic show up primarily in decisions to cross or enter traffic at intersections and access points. Research shows that older drivers have difficulty judging the position of approaching traffic in relation to their ability to accelerate across or into gaps. This difficulty shows up both in accepting inadequate gaps, with the risk of collision, and in passing up acceptable gaps, to the delay and dissatisfaction of those behind.

Visual search. Visual search seems less a concern than gap judgment at intersections, where the special problem of older drivers appears to lie more in what they perceive than where they look. However, elders' physical limitations in head and upper body motion often make looking behind before backing ("backing by sound") more difficult or cause them to fail to check their blind spot before changing lanes. Older drivers can overcome the latter problem by making certain mirror adjustments that largely eliminate the blind spot; however, drivers must be taught these changes and must be willing to make the readjustment.

Navigation. Navigation problems stem primarily from memory lapses and can range from simply missing a turn or taking the wrong turn to becoming lost and ending up far from their place of origin or their destination. Wrong or missed turns appear as a normal part of aging and may have as much to do with the driver's failure to acquire accurate information in the first place rather than with memory problems. More serious cases appear to be manifestations of brain deterioration, most notably Alzheimer's disease. The consequences of navigational shortcomings seem less a matter of safety than of inconvenience to the older driver.

Motor control. Motor-control difficulties show up among older drivers as tendencies to wander back and forth between lanes, cut across lanes, swing too wide in curves and corners, accelerate and brake erratically, and, once in a great while, in misapplication of the accelerator or the shift lever, resulting in crashes with structures or people. Because accidents resulting from these difficulties are often highly publicized, the public is often left with the impression that such accidents happen more often than is the case. Moreover, the risk associated with declines in motor control is greatly offset by traveling a lower speeds.

In summary, age-related shortcomings affecting elders' driving practices can pose a threat to the safety and mobility of the public. Fortunately, this threat is greatly moderated by the willingness of drivers to confine their operation to times, places, and conditions in which the effects of their shortcomings pose the least risk.

Declines in Older Driver Ability

The specific abilities showing declines with age and evidence of unsafe driving include the following:

• Visual ability. Elders experience some decline in their ability to differentiate stimuli clearly under normal conditions; under low illumination (night) and in low-contrast situations; for objects in motion; and in the presence of glare and after removal of glare. In addition, many experience narrowing of the visual field.
• Attention ability. Aging brings about declines in older drivers' ability to attend to important aspects of the driving environment, which includes range of attention as well as ability to attend selectively to specific elements, to share attention among different aspects, and to shift attention quickly.
• Perceptual ability. Older drivers experience declines in their ability to interpret correctly what is sensed: speed of perception, ability to detect motion, and ability to recognize various patterns within the visual field.
• Cognitive ability. The ability to acquire, store, and apply knowledge, including short-term and long-term memory as well as performing mental operations, shows some decline with age.
• Psychomotor ability. Many elders lose some of their ability to respond quickly to the appearance of a stimulus, to respond differently to different stimuli, and to coordinate eye-hand motion.
• Physical ability. Declines in strength, coordination, reach, and range of motion are normal with aging; they affect arms, legs, upper body, and neck. Some elders experience loss of consciousness.

Declines in these abilities appear with the older population as a whole and show small correlations with age as well as with accidents among older drivers. Yet, as with other forms of health risk, it is the small number of older drivers with severe deficits who tend to be involved in accidents. What the wealth of research into the relationship between age and accidents largely fails to determine is which of the many ability deficits actually cause accidents. Most of the research has been confined to examining one or a few abilities at a time. Research obtaining measures for a broad range of abilities within the same drivers shows intercorrelations among the various abilities themselves that generally exceed their correlations with indices of unsafe driving (McKnight and McKnight, 1999). There is hardly an ability whose relationship to unsafe driving cannot be explained by its relationship to other abilities that could be the true causes of accidents. The only sure way of establishing a causal relationship is experimentally, that is, by systematically varying certain abilities and observing changes in driving practices. Unfortunately, few age-related declines in ability are susceptible to experimental variation. Yet the improvement in driving that appears to have been achieved through modification of certain abilities to focus attention is evidence that these abilities play some causal role in safe driving.

Interventions to Address Declines in Ability

Identifying the unsafe. The fact that unsafe drivers make up a minority of the older-driver population creates the need for means of distinguishing the safe from the unsafe driver, one that is both valid and capable of being instituted without imposing an inordinate burden upon the total older-driver population. The responsibility for identifying drivers who are incapable of driving safely falls primarily to the licensing agency of each state. However, the focus of licensing is primarily assuring that new drivers have acquired the requisite ability to drive by assessing their knowledge through written tests, their skill through road tests, and their visual acuity through vision tests. Once the prospective drivers have passed all tests, further measurement is largely limited to vision tests administered as part of the license renewal process. While the frequency of renewal testing increases for older drivers, only two states, Illinois and Indiana, require demonstrations of skill or knowledge.

Police, families, and the medical community, roughly in that order of frequency, initiate the identification of unsafe older drivers primarily through reports to licensing agencies. Most states provide a mechanism through which police can report drivers whose accidents or violations of the law arouse suspicion of an ability deficit. Some states routinely require those reported upon to appear for examination, and other states limit their workload to some degree by requiring an examination only when there is evidence of deficit beyond mere violations or involvement in accidents. Families, principally adult offspring, are invited to report cases in which unsafe driving is accompanied by other observations suggesting deficits, a process encouraged in some jurisdictions by withholding the names of those reporting. Physicians are typically reluctant to report to the police patients with observed deficits, even in states where physicians are required to do so under the law and where they are provided immunity from any resulting lawsuits. However, after Pennsylvania passed a law making failure to report ability deficits a criminal offense and holding physicians liable for any resulting damages, reports reached 40,000 in the first year (1994), and the number continued to increase after that.

The means by which licensing agencies assess the abilities of at-risk older drivers reported to them vary considerably. While some simply readminister written, road, and vision tests, others refer some or all of such drivers to services designed specifically to assess the abilities that are required in driving and are prone to decline with age. Measures are available for assessing and detecting declines in the various skills that have been described. However, before taking any restrictive action, most licensing agencies will administer some form of road test as the ultimate determiner of driving ability.

Actions to reduce risk. The two alternative actions available in dealing with drivers who have dangerous ability deficits are to overcome the deficits and to restrict driving. The first alternative is clearly the most attractive to drivers as well as to the agencies that control driving. Most limitations in visual acuity revealed during license renewal are handled through changes in corrective lenses; advances in optics have eliminated cataracts, and recent research holds hope of overcoming some forms of blindness. Age-related muscular limitations in strength and flexibility range from the relatively minor effects of arthritis to the more severe effects of stroke. Occupational therapists specialize in helping older drivers overcome the deficits where possible and compensate for them where it is not. Developments in vehicle control assists, mirror systems and alignment, seats, and ways of getting in and out of vehicles have reduced the debilitating effects of many physical limitations.

Within the mental realm, there is evidence that certain attention deficits may be amenable to training in compensatory visual search practices. Several measures of attention span have shown a decline in the ability to detect peripheral stimuli lying within the sensory field of view. Instruction aimed at increasing the speed of processing has led to improved performance in on-road and simulator performance tests, although the effects upon everyday driving have yet to be evaluated.

Unfortunately, the progressive nature of ability declines ultimately necessitates restrictions in driving. Restrictions are largely self-imposed; as age increases, drivers tend to limit the amount, times, and locations of driving. Furthermore, when called in for testing, substantial numbers of older drivers fail to show up, allowing their licenses to be suspended. Where restrictions must be imposed, licensing agencies show reluctance to restrict driving any more than necessary, recognizing the importance of independent mobility of an age group largely settled in the suburbs, where personal transportation alternatives are generally limited. Restrictions imposed include operation only in daylight hours for those with visual limitations, operation at certain hours and in locations of sparse traffic for those with attention deficits, and operations in familiar areas for those with attention and memory deficits. Complete suspension tends to be reserved for drivers with very severe deficits that show up in road tests as well as through ability testing.

Providing Alternative Modes of Travel

• Coordination. Paratransit in most communities is furnished by a number of independent providers, serving a varied clientele. Coordination of services through a single agency permits more effective and economical use of available resources.

• Financial support. Providing highly responsive transit services at affordable prices requires substantial subsidization by local and state agencies. However, thise financial support is instrumental in coordinatingion of services.

• Ride-sharing. The ability to provide demand-responsive travel at affordable prices requires consumers to shareing of rides. While clients can go where and when they want, they will travel with others users, who are to be picked up and dropped off along the way. However, tThis aspect of paratransit has not proven a barrier to its use by an older clienteleconsumers.

• Advanced scheduling. Transporting clients from different locations to different destinations while minimizing travel time and distance involves complicated scheduling and routing. Most systems require that requests for rides be made well in advance. Some paratransit systems will gear charges to the degree of advance notice provided.

• Eligibility. Most communities have established eligibility requirements for subsidized transportation. Requirements include age, need for transportation, physical capability, and financial need.

Summary

Of course, there are notable exceptions, and the licensing process is called upon to take action when drivers show true cause for concern. While some deficiencies can be overcome through medical or instructional interventions, most cannot, necessitating imposition of driving restrictions ranging from specification of acceptable times and places to complete cessation of driving. Unfortunately, elders' need for mobility does not diminish with the inability to drive, and the focus of attention in recent years has shifted from getting older adults off the road to finding other ways of getting them around. This has proven to be a formidable task. Of the many alternative travel modes available, few are well suited to the needs of the elderly. Paratransit systems have not generally provided a means of transporting the elderly where and when they wish to go. However, with greater recognition of their travel needs have come more demand-responsive paratransit systems. These systems rely heavily upon coordination at the local level, financial support, ride-sharing, and advanced scheduling of rides.

A. James McKnight is president, Transportation Research Associates, Annapolis, Md.

References

Burkhardt, J. E. 2000. Coordinated Transportation Systems. Washington, D.C.: AARP.

Dulisse, B. 1997. "Older Drivers and Risk to Other Road Users." Accident Analysis and Prevention 29(5): 573-82.

Janke, M. K. 1994. "Mature Driver Improvement Program in California." Transportation Research Record 1438:77. Washington, D.C.: Transportation Research Board, National Research Council.

McKnight, A. J., and McKnight, A. S. 1996. Age Diminished Characteristics and Traffic Safety. Landover, Md.: Pacific Institute for Research and Development. Prepared under a grant from the Centers for Disease Control and Prevention, Atlanta, Ga.

McKnight, A. J., and McKnight, A. S. 1999. "Multivariate Analysis of Age-Related Driver Ability and Performance Deficits." Accident Analysis and Prevention 31(3): 337-46.

Miller, L., and Dimling, J. A., Jr. 1969. Driver Licensing and Performance, vol. 1, Research Review and Recommendations. Lexington, Ky.: Spindletop Research, Inc.

Mitchell, C. G. B. 2000. Some Implications for Road Safety of an Ageing Population. Transport Trends. London: Department of the Environment, Transport and the Regions, the Stationary Office.

National Highway Traffic Safety Administration (NHTSA). 2000. Traffic Safety Facts: 1999 Motor Vehicle Crash Data from FARS and GES. Washington, D.C.: NHTSA.

Organization for Economic Cooperation and Development (OECD). 2001. Ageing and Transport: Mobility Needs and Safety Issues. Paris: OECD Publications.

Owsley, C. 2002. "Driver Capabilities." In Proceedings of Transportation in an Aging Society: A Decade of Experience. Washington, D.C.: Transportation Research Board, National Research Council, The National Academies.

Staplin, L., et al. 1998. Intersection Problems of Older Drivers, vol. 2, Background Synthesis on Age and Intersection Driving Difficulties. Alexandria, Va.: The Scientext Corporation, performed under contract to the National Highway Traffic Safety Administration (contract DTNH -93-C-06237).

From Generations Summer 2003 issue, 27(2): 25-31. © 2003 American Society on Aging

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