Federal and state regulators are struggling to deal with one of the most vexing and fastest-growing roadway safety issues -- identifying the older drivers who pose a hazard while not discriminating against those who don't.
The number of motorists over 65 years old has doubled over the past 20 years. And while older people, as a group, have a lower rate of fatal accidents than teen-agers, their fatal-accident rates based on miles driven are among the highest, according to federal data.
Scientific research also suggests that reflexes and cognitive skills critical to driving deteriorate markedly after age 75.
But groups representing older motorists, as well as many researchers, are fiercely opposed to additional driving tests for the aging. And they argue that in a society reliant on automobiles, older people not only need driver's licenses, but see them as powerful symbols of self-worth.
"As a nation, we have turned away from the problems of older people, and transportation is no exception," said Sam Yaksich Jr., executive director of the Automobile Association of America's Foundation for Traffic Safety.
"Aging is something we don't like, and we've tried to block it out," he said.
Policies toward aging drivers are inconsistent, even contradictory.
While a few states require older motorists to take added tests, most do not. In some places, doctors are urged to alert regulators about patients who may pose a hazard behind the wheel; elsewhere, complaints from family members are ignored.
And while regulators and researchers search for answers, tens of thousands of Americans each year must decide what to do about an aging relative or friend whose driving skills are fading.
But accidents in which older drivers lose control of their vehicles are so common in such retirement areas as Florida that they are sometimes referred to as cases of "s.e.a." or "sudden elder acceleration."
Multiple car crashes at intersections also increase markedly with age because older drivers often do not react quickly enough to stop at red lights or stop signs, according to the Insurance Institute for Highway Safety, an industry-sponsored research group in Arlington, Va.
"We see older people coming into here all the time," said Dr. Charles Hartness, an emergency room doctor at St. Vincent's Hospital in Portland, Ore. "Most of the time, the accident is not serious, but then you pull their record and find out they had an accident six months earlier and another one three months before that."