Jeremy T. Bidwell, SFASU,Spring 2000
Return toPerception, Spring 2000 frontpage
With dramatic increasesin the number of motor vehicles on public roadways in this century,driving safety is an issue that affects every one of us. MostAmericans rely on the use of personal motor vehicles as their primarymeans of transportation, and must put themselves at risk every day.The risk of a motor vehicle accident increases when our perceptiveskills are degraded in any way. Such is the case with alcoholicintoxication, impairment from the use of narcotics, and loss ofperceptual accuracy due to any biological reason. One of the manyissues in current debate with regards to motor vehicle safety is thatof the growing numbers of elderly drivers on public roadways and theperceptual problems they may encounter with age. Age-related visionloss is becoming a more prevalent issue in roadway safety. Moststates require a simple form of vision testing in order to become alicensed driver. These tests are rapidly being seen as inadequate,and in need of revision. Some states do not at all require a visiontest to become licensed to drive. Currently, the states not requiringvision tests for license renewal include: Alabama, Connecticut,Kentucky, Mississippi, New Jersey, Oklahoma, Pennsylvania, Tennessee,Vermont, and West Virginia. These states could cut the accident ratein people over age 60 by 12 percent, if they would simply utilizetesting procedures (N.S., 1999). In this paper, issues facing theaging driver, and possible solutions to ensure safe roadways for thepublic as a whole, will be explored.
The average driverís age is steadily increasing. Censusestimates show that by the year 2020, approximately 50 million peopleover the age of 65 will be eligible to drive on public roadways (Cobb& Coughlin, 1998). With a significant increase in the number ofpeople likely to be affected by age-related vision loss, society mayneed to re-evaluate vision standards for license testing. It isstandard practice for a motor vehicle bureau to test only visualacuity. This practice does not take into consideration perceptuallyimpairing factors encountered in driving such as glare or fog(Voelker, 1999). Thelack of adequate visual testing is commonplace in all states thattest vision ability. It has been found however, states that at leasttest for visual acuity during license renewal have approximately 12percent less automobile accident deaths among older drivers (Voelker,1999). One study showed that visual acuity is less powerful inmeasuring the likelihood of a crash than useful field of visiontesting, suggesting a need for change (Owsley et al., 1998).
One of the largest problems that face aging drivers arecataracts. Because they often form over an extended time period, somesymptoms may go initially unnoticed. A study at the University ofAlabama at Birmingham found that people who develop cataracts weretwo and a half times more likely to be involved in a motor vehicleaccident than those who do not (Voelker, 1999). A similar studyshowed that the same percentage of drivers with cataracts would beinvolved in at-fault accidents (Owsley, Stalvey, Wells, & Sloane,1999). Cataracts are likely to affect glare sensitivity, contrastsensitivity, and acuity in a negative way. Fro example, contrastsensitivity loss can lead a person to become eight times more likelyto be in an accident (Voelker, 1999). Cataracts affecta large number of peoplein the population, about half of those over seventy-five years of age(Owsley et al, 1999). Today, cataract surgery is more common than anyother surgery claimed by Medicare beneficiaries, representing 12percent of the entire budget allocated by Medicare (Owsley et al,1999). Perhaps if the people with cataracts could be identifiedduring license renewal through more comprehensive vision testing,they could be deferred for proper medical care prior tolicensing.
Another problem facing the older driver isthat current highway and roadway design was not created with theirdeteriorating perceptual systems in mind. Any decrease in visualacuity can seriously affect oneís ability to read standardstreet signs. The current standard for street sign legibility set bythe 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 offorty percent of drivers over age 65 (Alicandri, Robinson &Penney, 1999). Reduced contrast sensitivity is particularly hazardousin detecting pedestrians present when illumination is insufficient,also contributing to a difficulty with seeing worn lane dividinglines (Alicandri et al, 1999). These characteristics of roadways areproblems that can potentially be repaired, but the need is not greatuntil one looks at the problems associated with aging drivers.Testing standards, both perceptual and motor, are aimed at testingthe driver under ideal circumstances. However, roadway conditions, aswell as environmental factors usually place every driver in less thanideal conditions. To ensure safety, testing must be modified toaccount for factors encountered in less-than-ideal drivingconditions. Teaching one to parallel park between cones in an emptyparking lot is not sufficient for real-world application. Using thesame logic, measuring oneís simple visual acuity in a highcontrast setting is not practical for what is encountered duringdriving on public roadways. People that have age-related visiondeficits may have acuity suitable enough to pass a driving test. Inmany cases, however, when driving conditions worsen, their visualability diminishes at an accelerated rate.
Adding to the above motioned problems is theneed for independence felt in our society. Unfortunately, as ageincreases, often times so does the need to provide transportationindependently. Between 1969 and 1990, the number of elderly driversincreased by more than fiftypercent (Cobb &Coughlin, 1998). Accompanying the lack of adequate highway design forthe elderly is a general lack of public transportation. In denselypopulated areas, public transportation is common, but not widelyavailable in smaller communities. Many people choose to leave theseurban areas after retirement, and become vastly reliant on privatemodes of transportation. It is a simple matter of statistics. Themore people there are on the roadways that are likely to haveage-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 inAmerican 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 publictransportation necessary to provide our older citizens the freedom totravel as they see fit. Improving roadway conditions is a small stepin the right direction. Better lighting at night, larger signs withmore contrast, and wider lanes on roadways can help to decrease thenumber of accidents caused by elderly drivers. The automotiveindustry has already made significant changes in instrument design,and other human factors considerations to assist the older generationof consumers. Until public awareness and interest is high enough toaffect the actions of legislators and public safety administrators,condition improvements may be slow. The aging segment of drivers is agrowing group of people, and will soon be large enough to warrant theattention of society at large.
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?: Problemdefinition and political impact.Journal of Aging Studies, 12,411
N.S., (1999, October 16). Car safety tied tovision testing, clarity. ScienceNews, 156, 255.
Owsley, C., Ball, K., McGwin, G., Sloane, M. E., Roenker, D.L., White, M. & Overly, T., (1998). Visual processing impairmentand risk of motor vehicle crash among older adults.Journal of the American MedicalAssociation, 279 (14),1083-1088.
Owsley, C., Stalvey, B., Wells, J. &Sloane, M. E. (1999). Older drivers and cataract: Driving habits andcrash 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 MedicalAssociation. 282, (17), 1610.