As society ages, the safe mobility of older people will be an increasingly vital area of research. The head of the National Highway Traffic Safety Administration's older driver research program, John Eberhard, is one of the foremost researchers in the field. In response to questions, he provided Status Report with his perspective.
STATUS REPORT: Are older drivers a significant public health problem?
JOHN EBERHARD: They are not a serious threat to the health and safety of other motorists. They kill fewer motorists and pedestrians than drivers of any other age group. They have the lowest crash involvement rates per licensed driver, the lowest rates of alcohol impairment, and the highest rates of seat belt use among adults. The real public health issue is the health and safety of older drivers and occupants themselves. ... There are more older occupants dying each year in crashes than there are occupants of all ages killed in rollovers or in crashes attributed to distracted driving — two high-profile areas that receive a great deal of public attention and funding. What is a problem for older drivers is their increasing exposure and the reduced ability to protect frail occupants in a crash. Since there will be more older people licensed and driving than ever before, they will be in more fatal crashes.
SR: Which older drivers are at highest risk?
JE: The healthiest and wealthiest probably are the ones most likely to get into crashes. They drive much more, which is the best predictor of crashes.
SR: Are there any good screening tests to identify older drivers who should reduce or stop driving?
JE: There are a number of research efforts under way to develop screening tests, and some have shown some effectiveness. Whether we can develop screening tests that can be given cost-effectively to the overall driving population or drivers over a certain age is another issue. A key problem is that it's very difficult to predict such rare events as traffic crashes. Some investigators claim that we would have to take over 500 drivers off the road to prevent one crash. Since driving is so important, we don't want to needlessly deny safe older people this means of getting around. ... Because of the infrequency of crashes, it is difficult, if not impossible, to develop tests with sufficient sensitivity to identify those who will crash yet specific enough not to unduly deny those who will not. Over my 30 years with the National Highway Traffic Safety Administration, I have not yet seen any test that is sufficiently valid to fairly identify the at-risk driver.
SR: If screening tests were useful and necessary, should DMVs do the screening?
JE: Screening tests may be more useful in the hands of clinicians, such as driver rehabilitation specialists. Whether licensing agencies should engage in aged-based testing is another issue. It's very difficult to design tests that will pick out those who will crash from the numerous ones who will not. There are a number of activities going on right now to look at testing of older people. ... We should evaluate these programs to determine whether they can identify those who are unsafe with enough sensitivity and specificity that they don't take safe older drivers off the road. We should also determine whether these programs can keep functionally limited older people safely on the road as drivers or alternative transportation users.
SR: Are there enough alternatives to driving available to older people?
JE: This should actually be two questions — whether enough alternatives exist and whether older people use them. There are a few major efforts under way to address the availability area that will develop best practices and identify good current programs. ... The other issue is whether older people are using the programs. Use is rather low, as has been repeatedly shown by the Nationwide Personal Transportation Survey, which shows less than 3 percent usage by people age 65 and older. Most older people don't use, don't know how to use, and don't care to use other options, according to focus groups I conducted a couple of years ago.
SR: Are there ways to change vehicle design and safety features to better protect older occupants?
JE: Yes, we need to work with the manufacturers to have them get ready for this population. We need to improve safety belts and airbag systems so that they are not aggressive to the older occupant's more fragile head and chest. For example, airbags with dual-stage inflator technology could provide a depowered, or a lower level of, inflation for an older driver or other occupant. A driver and occupant identifier (a key sensor, touch pad sensor, or an electronic driver's license) would be needed to let the control module know an older occupant is in the vehicle. Force-limited belts or belts with high elongation webbing also could work in conjunction with airbags to reduce the loads on an occupant's chest. Futuristic four-point belts, such as those in the Volvo concept car, or inflatable belts may also work to distribute the loading on the occupant's chest. Other improvements to minimize the risk to older occupants could include adjustable pedals and improved seat and steering column adjustments to allow more room between the driver's chest and the airbag and better visibility of the road.