Jeremy T. Bidwell, SFASU, Spring 2000
Return to Perception, Spring 2000 frontpage
With dramatic increases in the number of motor vehicles on public roadways in this century, driving safety is an issue that affects every one of us. Most Americans rely on the use of personal motor vehicles as their primary means of transportation, and must put themselves at risk every day. The risk of a motor vehicle accident increases when our perceptive skills are degraded in any way. Such is the case with alcoholic intoxication, impairment from the use of narcotics, and loss of perceptual accuracy due to any biological reason. One of the many issues in current debate with regards to motor vehicle safety is that of the growing numbers of elderly drivers on public roadways and the perceptual problems they may encounter with age. Age-related vision loss is becoming a more prevalent issue in roadway safety. Most states require a simple form of vision testing in order to become a licensed driver. These tests are rapidly being seen as inadequate, and in need of revision. Some states do not at all require a vision test to become licensed to drive. Currently, the states not requiring vision tests for license renewal include: Alabama, Connecticut, Kentucky, Mississippi, New Jersey, Oklahoma, Pennsylvania, Tennessee, Vermont, and West Virginia. These states could cut the accident rate in people over age 60 by 12 percent, if they would simply utilize testing procedures (N.S., 1999). In this paper, issues facing the aging driver, and possible solutions to ensure safe roadways for the public as a whole, will be explored.
The average driverís age is steadily increasing. Census estimates show that by the year 2020, approximately 50 million people over the age of 65 will be eligible to drive on public roadways (Cobb & Coughlin, 1998). With a significant increase in the number of people likely to be affected by age-related vision loss, society may need to re-evaluate vision standards for license testing. It is standard practice for a motor vehicle bureau to test only visual acuity. This practice does not take into consideration perceptually impairing factors encountered in driving such as glare or fog (Voelker, 1999). The lack of adequate visual testing is commonplace in all states that test vision ability. It has been found however, states that at least test for visual acuity during license renewal have approximately 12 percent less automobile accident deaths among older drivers (Voelker, 1999). One study showed that visual acuity is less powerful in measuring the likelihood of a crash than useful field of vision testing, suggesting a need for change (Owsley et al., 1998).
One of the largest problems that face aging drivers are cataracts. Because they often form over an extended time period, some symptoms may go initially unnoticed. A study at the University of Alabama at Birmingham found that people who develop cataracts were two and a half times more likely to be involved in a motor vehicle accident than those who do not (Voelker, 1999). A similar study showed that the same percentage of drivers with cataracts would be involved in at-fault accidents (Owsley, Stalvey, Wells, & Sloane, 1999). Cataracts are likely to affect glare sensitivity, contrast sensitivity, and acuity in a negative way. Fro example, contrast sensitivity loss can lead a person to become eight times more likely to be in an accident (Voelker, 1999). Cataracts affect a large number of people in the population, about half of those over seventy-five years of age (Owsley et al, 1999). Today, cataract surgery is more common than any other surgery claimed by Medicare beneficiaries, representing 12 percent of the entire budget allocated by Medicare (Owsley et al, 1999). Perhaps if the people with cataracts could be identified during license renewal through more comprehensive vision testing, they could be deferred for proper medical care prior to licensing.
Another problem facing the older driver is that current highway and roadway design was not created with their deteriorating perceptual systems in mind. Any decrease in visual acuity can seriously affect oneís ability to read standard street signs. The current standard for street sign legibility set by the U.S. Department of Transportation uses visual acuity of 20/25. This is higher than the standard set for licensing in most states, which on average is 20/40, and also exceeds the visual capability of forty percent of drivers over age 65 (Alicandri, Robinson & Penney, 1999). Reduced contrast sensitivity is particularly hazardous in detecting pedestrians present when illumination is insufficient, also contributing to a difficulty with seeing worn lane dividing lines (Alicandri et al, 1999). These characteristics of roadways are problems that can potentially be repaired, but the need is not great until one looks at the problems associated with aging drivers. Testing standards, both perceptual and motor, are aimed at testing the driver under ideal circumstances. However, roadway conditions, as well as environmental factors usually place every driver in less than ideal conditions. To ensure safety, testing must be modified to account for factors encountered in less-than-ideal driving conditions. Teaching one to parallel park between cones in an empty parking lot is not sufficient for real-world application. Using the same logic, measuring oneís simple visual acuity in a high contrast setting is not practical for what is encountered during driving on public roadways. People that have age-related vision deficits may have acuity suitable enough to pass a driving test. In many cases, however, when driving conditions worsen, their visual ability diminishes at an accelerated rate.
Adding to the above motioned problems is the need for independence felt in our society. Unfortunately, as age increases, often times so does the need to provide transportation independently. Between 1969 and 1990, the number of elderly drivers increased by more than fifty percent (Cobb & Coughlin, 1998). Accompanying the lack of adequate highway design for the elderly is a general lack of public transportation. In densely populated areas, public transportation is common, but not widely available in smaller communities. Many people choose to leave these urban areas after retirement, and become vastly reliant on private modes of transportation. It is a simple matter of statistics. The more people there are on the roadways that are likely to have age-related vision problems, the more accidents will occur.
Solutions for this problem are complex. There is a struggle to balance personal liberty, an idea cherished in American society, with public safety. If vision standards are raised, more people will inevitably be deprived of their freedom to drive. The American government cannot at the present time provide the public transportation necessary to provide our older citizens the freedom to travel as they see fit. Improving roadway conditions is a small step in the right direction. Better lighting at night, larger signs with more contrast, and wider lanes on roadways can help to decrease the number of accidents caused by elderly drivers. The automotive industry has already made significant changes in instrument design, and other human factors considerations to assist the older generation of consumers. Until public awareness and interest is high enough to affect the actions of legislators and public safety administrators, condition improvements may be slow. The aging segment of drivers is a growing group of people, and will soon be large enough to warrant the attention of society at large.
References
Alicandri, E., Robinson, M., & Penney, T. (1999, May). Designing highways with older drivers in mind. Public Roads, 62, 18-23.
Cobb, R. W., &
Coughlin, J. F. (1998). Are elderly drivers a road hazard?: Problem
definition and political impact.
Journal of Aging Studies, 12,
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N.S., (1999, October 16). Car safety tied to
vision testing, clarity. Science
News, 156, 255.
Owsley, C., Ball, K., McGwin, G., Sloane, M. E., Roenker, D.
L., White, M. & Overly, T., (1998). Visual processing impairment
and risk of motor vehicle crash among older adults.
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1083-1088.
Owsley, C., Stalvey, B., Wells, J. &
Sloane, M. E. (1999). Older drivers and cataract: Driving habits and
crash risk. Journals of Gerentology:
Series A, Biological Sciences and Medical Sciences, 54
(4), 203-211.
Voelker, R. (1999). Crash risk among older drivers studied. Journal of the American Medical Association. 282, (17), 1610.