Traffic deaths jumped 14 percent in Virginia during 1986 as low gasoline prices and economic growth generated a record number of drivers on the state's roads and highways, the Department of Motor Vehicles reported yesterday.

In its annual study of traffic fatalities and accidents, the department said that 1,118 persons died and 79,188 were injured in crashes. It was the highest death toll on state roads since 1977, when 1,145 people died.

The Northern Virginia district, which includes Alexandria and the counties of Arlington, Fairfax, Prince William, Loudoun and Fauquier, recorded 157 fatalities, up from 114 in 1985.

The Virginia increase was much higher than the 6.8 percent rise posted in Maryland, which had 790 traffic deaths in 1986, up from 740 the year before.

Traffic deaths in the District of Columbia declined in 1986, to 46 from 62 a year earlier, according to a spokesman for the D.C. police department.

"We're killing about as many people every day on the highway as were killed in that plane crash in Michigan," said Brian O'Neill, president of the Insurance Institute for Highway Safety, referring to the Aug. 16 crash of a Northwest Airlines jet in Detroit that killed 156.

O'Neill suggested that "the disproportionate attention paid to air safety" stems from "the perception that we're out of control when we board an airliner, that we're in the hands of the pilot and air traffic controllers, while on the highway we're in total control. But the reality is that we aren't. We're at the mercy of all those other road users."

Nationwide, 46,056 people died in car crashes in 1986, a 5 percent increase over 1985, according to the National Highway Traffic Safety Administration.

The Virginia report shows that drunk driving continues to be a major contributor to highway accidents. Alcohol was involved in crashes that killed 492 people in 1986, or 44 percent of the total and a 2.7 percent increase over 1985. In the Northern Virginia district, 54 persons died in alcohol-related crashes.

The report said that 52 youths aged 15 to 19 died in alcohol-related crashes throughout the state, a 30 percent increase from 1985. Neither Maryland nor the District have developed comparable figures.

Paige Tucker, a spokeswoman for the Virginia Department of Motor Vehicles, said that comparisons of the alcohol-related crash data between 1985 and 1986 are misleading because of a change in the way the information was gathered.

Beginning last year, she said, the department began using medical examiners' reports in addition to police reports, which sometimes overlooked the presence of alcohol in fatal crashes. "By the time a police officer got to the scene, the victim may already have been taken to the hospital, so he might not have known," Tucker said. "So basically in 1985 and 1986, we're comparing apples and oranges."

The death rate on Virginia's highways was 2.2 fatalities per 100 million miles traveled by vehicles, up from 2.1 in 1985, the report said. However, the death rate in 1985 was the lowest in a decade, "so you're comparing 1986 with a particularly good year," Tucker said.

In Maryland the death rate rose slightly from 2.19 per 100 million vehicle miles in 1985 to 2.21 in 1986. In the District, it dropped from 1.86 in 1985 to 1.3 in 1986, a reflection of the drop in city fatalities.

The Virginia report said the number of registered vehicles in 1986 was 4.5 million, a 5.2 percent increase from 1985. The number of miles traveled by vehicles in the state was 51.6 billion, a 9.3 increase from 1985, the report said.

"You have to keep it in perspective," Tucker said. "More people were driving, more cars were out there and they were traveling more miles. When you've got increases like that, it's pretty customary to have increases in the number of fatalities and accidents."

Virginia's highway safety record appears to be consistent with national trends. "The death rate per mile traveled . . . sort of goes down every year," said O'Neill.

"But in the last few years, with increasing travel speeds and more traffic congestion, we're seeing the absolute number of deaths increase," he said.

The motor vehicles department said in its press release that enforcement of drunk-driving laws is becoming more vigorous, noting that arrests for the offense in the first quarter of 1987 may have risen as much as 10 percent over the same period in 1986.

The report said that 87.9 percent of those arrested for drunk driving were convicted in 1986, an increase of 1.2 percent over the previous year.

In Northern Virginia, the largest number of fatal crashes occurred in Fairfax County, which recorded 84 deaths in 1986.