Who's the more likely menace -- the 18-year-old riding your bumper on the Beltway or the 85-year-old driver crawling at 40 mph in front of you?
Conventional wisdom says it's the kid. After all, teens have more accidents than anyone else.
But federal reports say the 85-year-old has the higher risk of crashing when he's on the road, even though the elderly generally drive less and have fewer accidents.
The comparison is not just academic. As the Baby Boom generation grays, more and more elderly drivers will be on the road, posing special safety problems that states may have to address.
On the other hand, senior citizens represent a powerful lobby. They turn out to vote, and so far they've managed to ward off special examinations or restrictions in most states.
By the year 2020, people age 65 and older are expected to make up almost 20 percent of the U.S. population, compared with 12 percent in the mid-1980s, according to the National Highway Traffic Safety Administration.
The crash statistics are startling. Sixteen to 19-year-olds have almost 30 crashes per million miles traveled, compared with about 40 crashes for those 85 and older, an NHTSA report says.
Drivers from 35 to 65 years old are the safest, but the accident rate per mile driven begins climbing after 70. After 75, people are twice as likely to be involved in a crash, per mile driven, as younger people.
Two back-to-back tragedies caused by elderly drivers this spring focused national attention on safety issues.
In New York, a 74-year-old woman killed five people and injured 26 others when she lost control of her car and drove into a crowded park. The driver contended she could not stop the car, although there was no evidence of a mechanical problem.
A few weeks later, an 87-year-old man plowed into a group of third-graders in Chicago, killing one child and injuring others. He was charged with a minor traffic offense, a Chicago police spokesman said.
Locally, an 83-year-old Parkville woman lost control of her 1974 Mercedes-Benz last Monday and struck a 14-year-old girl. The car pinned the teen against a wall and crushed her legs, causing serious injuries. Police said charges are pending.
Cases in which elderly drivers kill or maim children make the most headlines, although more often than not, elderly drivers are the ones to lose their lives.
Because of their physical vulnerability, senior citizens are much more likely to be killed in an accident than middle-aged drivers, said Dr. Robin A. Barr of the National Institute on Aging in Bethesda.
While fatalities for drivers of all ages dipped 8 percent during the 1980s, fatalities for drivers 65 and older rose by 43 percent, he said.
Studies show that the physical and mental attributes required for driving decline with age and certain diseases. They include eyesight, hearing, reaction time and the ability to judge complex traffic situations.
However, the rate of decline differs for everyone. One driver may be quite capable at 88; another may have trouble at 68.
Busy highways can be especially confusing to the elderly.
In 1990, for example, an 87-year-old Cape St. Claire woman drove 5 miles the wrong way on U.S. 50. She wasn't hurt, but two minor accidents occurred along the way. Police said advanced age may have affected her judgment.
The elderly are more likely to crash in urban areas during daylight hours and to hit another car, federal statistics show. They have more trouble making turns and merging into traffic than younger drivers.
Those trends could be seen in a 1991 accident on U.S. 50. An Annapolis couple, both 74, died after the husband tried to make a left turn and hit an oncoming pickup truck. Several other people, including a 3-year-old, were injured.
Nonetheless, many states, including Maryland, do not have special licensing procedures to weed out older drivers whose skills have declined.
States often try to err on the side of the elderly, who have a powerful lobby in Washington and state capitals. Maryland law, for one, prohibits the Motor Vehicle Administration from using a driver's age as grounds for re-examination.
Any Marylander may be re-examined if he has a medical problem that affects driving or if he abuses alcohol or drugs, said MVA chief W. Marshall Rickert. The elderly make up a minority of those cases, however, perhaps because their doctors or families don't wish to report them.
Mr. Rickert said he is waiting for the results of studies by a national association of motor vehicle administrators before deciding whether Maryland's licensing system should be changed.
He and others in the field say they're trying to balance safety with elderly peoples' need for transportation and independence.
Older drivers have fought efforts to single them out for re-testing. "We're clearly opposed to age-based testing," said Ted Bobrow, a spokesman for the American Association of Retired Persons, which offers driver safety courses to its members.