Are Older Drivers At Risk?

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Why Driving Gets More Dangerous

As one ages, specific functions related to driving skills may be impaired. These functions include vision, hearing, sensation, and cognitive and motor abilities.

Motor abilities that decline as people age include peripheral vision, which may affect the ability to pass approaching vehicles safely; and the decreased range of motion, which may impair the ability to look behind when backing up. In addition, reaction time decreases by almost 40 percent on average from age 35 to 65.

The aging process may affect cognitive skills too. Short-term memory loss, for instance, can impair driving skills by interfering with a person's ability to process information efficiently when merging with traffic or changing lanes. Such difficulties are magnified when the older driver performs these driving skills under stressful conditions. The higher incidence of cognitive impairment, particularly dementia, among older adults produces an increased risk of accident involvement.

The surrounding driving environment may also interfere with the safety of older persons when they drive. For instance, the design and location of modern roadways can be intimidating to older drivers. Transportation planners have given little consideration to designing roads in ways that accommodate the increasing number of drivers with reduced vision or reaction time. Highways separate residential areas from commercial areas, thereby increasing both the complexity and distance involved in reaching necessary services.

Many traffic signs have not been designed for an aging population. Lettering is often small, signs with a large amount of information may be confusing, and the spacing of the letters may create a reading problem even for a person with a mild vision impairment.

According to the Federal Highway Administration, a decrease in visual acuity can cause difficulty in reading signs. The current standard for sign legibility -- 50 feet (15.24 meters) of legibility distance for each inch (2.54 centimeter) of letter height -- presumes visual acuity of 20/25. This is not only higher than the visual acuity standard for licensing in most states, which is usually 20/40, but exceeds the visual capabilities of 40 percent of drivers older than 65. Reductions in contrast sensitivity start at around 40 years of age.

Reduced contrast sensitivity can affect the detection of pedestrians in low-light situations and the detection of worn lane lines. Glare sensitivity makes driving at night or entering and exiting tunnels very difficult, and this condition is exacerbated by cataracts.

Cognitive changes (attention and reaction time) are perhaps the most varied with age. Working memory, selective attention, and processing speed are most often affected in normative aging. Deteriorating working-memory functions make it difficult to process information if the density of signs is excessive. Memory issues also make phased variable message panels harder to interpret. Selective attention problems make it difficult for older drivers to pick out the most critical information when they are confronted with a wide array of signs. Processing speed affects perception-reaction time, particularly in situations where the response requires choosing between alternatives (i.e., brake or steer).

• At-grade intersections.
• Interchanges.
• Roadway curvature and passing zones.
• Construction/work zones.

The FHWA older driver program is reaching out to practicing traffic engineers and highway designers to provide them with the knowledge of the wide variety of countermeasures that can be implemented to better meet the needs of older road users. While the guidelines are specifically geared toward improving the safety and mobility of older drivers, the benefits of these changes will be experienced by the entire driving public.

There are several approaches to increasing safety for people who rely on the automobile as their major source of mobility. Transportation experts are seeking ways to improve the driver, the vehicle, and the driving environment.

Improving the Driver

Transportation experts at universities and in state and federal offices are conducting research and developing ways to improve driver assessment, so that impairments of driving skills can be accurately identified. A 1996 study shows that simulators can both identify impaired skills and teach the driver how to compensate for the impairment. Other research is attempting to develop predictive screening methods using both performance in skills tests and driving records.

Some states have enacted laws that use age as a screening tool to identify risky drivers. These states require special testing for renewal such as knowledge tests, vision tests, or road tests. However, researchers do not currently know whether age-based requirements result in removing unsafe drivers from the roads or in simply reducing the number of older drivers, whether they are safe drivers or not.

State licensing policies can also extend the period during which a person with minor limitations can drive safely. Sixteen states have enacted graduated licensing laws. These laws enable the state to identify driving conditions under which a particular driver might be unsafe and then to issue a graduated license that restricts the person from driving under those unsafe conditions. Holders of graduated licenses might be licensed to drive only under specific conditions relating, for example, to time of day, destination, or type of vehicle.

In addition, driver retraining courses are available. AARP has developed a driver education program called the 55 ALIVE/Mature Driving program, which is completed by about 640,000 older drivers annually. Thirty-four states and the District of Columbia have laws that require insurance premium discounts or reductions in infraction points for older people who take an approved driving course like 55 ALIVE.

Older drivers can also adopt different travel patterns for safety, such as driving shorter distances, driving less at night, and avoiding rush hours, major highways, and bad weather conditions.

Improving the Vehicle

Safety experts are giving special consideration to enhancing the safety of vehicles for older drivers. These changes can benefit all drivers. For instance, automobiles are being designed with special adaptations to make driving easier, such as wide-angle rear-view mirrors. In addition, new technologies such as crash avoidance alarms and night vision enhancement systems are being developed to supplement functions needed for driving.