Fairfax County officials have attributed the surprisingly easy victory of the county's largest school bond issue to voters' inclination shun partisan voting on school issues, their confidence in the school system and timing.

"In Fairfax County, the Republicans want as good an education as the Democrats do," said Supervisor Thomas Davis (R-Mason). "Test scores are up and we're doing well on college entrances . . . . People have always been proud of the school system."

"I think that Fairfax County has reasserted its confidence in the school system," said Supervisor Joseph Alexander (D-Lee District).

The school bond issue was less vulnerable in the general election because the majority of voters were unaware of the criticism from local boards and civic groups, according to Supervisor Audrey Moore, D-Annandale. "In a special election, where only people who are into local government come out to vote, I think the bond issue would have had a poor chance."

Some county officials had predicted that the $74.8 million school bond issue, which will finance the construction of new schools and the renovation of old ones, was headed for defeat. It was opposed by the influential Federation of Citizens Associations, was criticized by other strong countywide organizations, and received only lukewarm endorsement by the Board of Supervisors. Three members of the previous school board even cast votes against the proposal when it came before them in July.

There was concern also that the presidential election would result in a high turnout of conservative voters set on reelecting Ronald Reagan and not interested in increasing local government spending.

The last two defeats of major school bond proposals were in 1972 and in 1975, and both came in local elections.

Along with its good timing, the school bond issue also had "a little bit of everything for everybody," according to Davis, offering new schools for residents in the growing part of the county and renovated schools for the declining population in the east.

One of the Federation of Citizens Association's criticism of the bond was that it broke the school system's longstanding policy against piecemeal improvements. Sally Ormsby, the federation's president, said voters on Tuesday "just looked at the benefits their communities would be receiving and ignored the broader picture."

John F. Herrity, chairman of the Board of Supervisors, said the bond also benefited from the county's increasing economic self-reliance in the last nine years. Since the last defeat of a school bond, Fairfax's growing economy has attracted residents who are not oriented towards Washington, but who live and work in the county. "Schools are one of the main reasons why people have located their businesses in Fairfax County, and so people here want good schools," Herrity said. Most of the $8,000 raised by school bond supporters came from the county's business community.

In Prince William County, however, politicians said the county's tradition of rejecting bond issues was one of the main reasons why a $20 million road bond lost by a 3 to 1 margin in Tuesday's election.

Prince William has rejected eight of the 10 bond issues that have been put before voters since 1974, and some politicians believe the county has a solid block of voters that fears higher taxes resulting from the public debt created by selling bonds.

Also, the road bond received lukewarm support from the supervisors themselves, who had voted unanimously to put it on the ballot. "I think there is a natural tendency that if you see something that may go down you try to pedal away from it," said Democratic Supervisor G. Richard Pfitzner.