For 20 years, there was nothing that distinguished Dodson Drive, with its fashionable homes and towering oak trees, from any other quiet residential street in Annandale's Hillbrook Forest subdivision.

Then, on the first night of August, the vandalism began. Residents awakened to find tires slashed or deflated on eight cars. Two mornings later, a housewife discovered that her car had been doused with gasoline and set aflame, extinguished only by heavy rains the night before.

Two nights later, a third neighbor was roused at 2 a.m. to find that his auto had been set on fire. Flames quickly spread to his carport and his home, cuasing $3,500 in damages.

In many ways, the Dodson Drive vandalism was typical of the more than 19,000 cases -- 26 incidents per day -- reported in Fairfax County in fiscal 1979 and 1980. It has ended as mysteriously as it began: with no witnesses, no motive and no suspects.

According to police and government estimates, those cases cost county residents more than 2 million each year, and police fear that the total incidents of vandalism may be "half again as many as that reported figure." But there is no way to gauge the cost of lost peace of mind. "Somebody could have been killed," complained a 57-year-old Dodson Drive resident scheduled to undergo heart surgery next week. "Then my wife will be here alone." Said another resident: "Now we're staying up nights, trying to keep watch on our homes."

In the Fairfax County school system alone, vandalism in the 1978 and 1979 school sessions amounted to more than $770,000, according to management engineer Ray McGuire. Annual damage to county park equipment and grounds averages about $26,000, officials reported.

But vandalism against homeowners accounts for most monetary damages, say police. They add that most vandalism is committed by juveniles, some as young as 12 years old.

"There is no question that vandalism is the most prevalent crime in the county," said Capt. Dan Mustaine, assistant bureau commander for the seven Fairfax County district police stations.

"It presents a very difficult situation for police in that these are crimes of immediacy," Mustaine said. "There is no planning involved. They are usually just riding through an area and the thing gets contagious. The vandalism occurs very swiftly and they are gone."

Crime records show that the number of reported incidents of vandalism declined from 10,432 in fiscal 1979 to 8,750 cased in fiscal 1980. Most police officials attribute the decline to the renewed use of foot patrols, and the Neighborhood Watch program in which neighbors report any strangers or unusual behavior and generally watch out for each other's homes.

"Those are by far the best deterrents that we have," Mustaine said.

But it is impossible to tell whether vandalism has declined, since police believe many minor cases go unreported.

"What we get are the larger cases where residents have to make reports in order to collect insurance," said Fairfax police spokesman Warren Carmichael. "But some victims just don't bother. There conceivably may be half again as many that go unreported."

"You can't single out one part of the county and say most occurs there," Mustain said. "It happens all over. What does it cost in worrying? tThere's the wife who is afraid to open her mailbox because it might explode. Some people become very afraid of what is going to happen on any given night. An expense you can't assess is the loss of peace of mind," Mustaine added.

In 1978, one of three students accused of starting the $4.5 million Fort Hint High School fire told authorities that vandalism was "the only way to get back at a school administration that treats you like a child."

At the height of the 1979 gasoline crisis, someone slashed 65 gasoline hoses at eight Northern Virginia service stations, police said.

In November 1979, carloads of teenagers terrorized a Vietnamese church in Annandale, destroying property and disruputing service.

More recently, Fairfax police arrested a 12-year-old boy and charged him with 13 counts of destruction of private property one month after tires had been slashed on 13 cars outside a Reston apartment house.

In July, authorities arrested a 17-year-old youth who was placed in a juvenile shelter after he appeared outside a Cheviot Drive home in Reston and pelted it with dozens of eggs.

In 1978 and 1979, Fairfax police arrested 985 county residents on vandalism charges, and 378 of the incidents -- more than 38 percnet -- were committed by juveniles aged 17 or younger.

"I hesitate to call it a common denominator, but most seem to be done by people between the ages of 16 to 22, with the 17-18 class the highest," Mustaine said. "I guess it's part of the unrest that all kids experience. They don't have any direction in their lives."