Fairfax County officials unveiled a list of transportation projects yesterday that they hope can be completed in three years if voters approve a $150 million road bond referendum in April.

The projects to be financed by the proposed referendum, the largest ever in the county, include $31.2 million for two stretches of the Springfield Bypass, $14.8 million for the Rte. 50-West Ox Road interchange and $15.3 million for the South Van Dorn Street-Capital Beltway interchange.

In addition, $20 million would be used to establish a fund for land acquisition in such areas as the Rte. 28 corridor, and $15 million would finance three "park and ride" commuter lots, two garages for county vehicles and commuter rail parking lots.

County Executive J. Hamilton Lambert said the main criterion used in selecting the proposed projects was how quickly construction could be started.

The program addresses several issues, he said, "including expediting highway construction, aggressively moving with commuter rail, aggressively moving with commuter parking and intersection improvements."

Lambert said he thought voters would approve the referendum, tentatively scheduled for April 12.

"I do not anticipate it having any impact on the tax rate. It will have an impact on the {annual budget} because we'll have to set aside sufficient funds to retire the debt," he said.

County Board Chairman Audrey Moore echoed his optimism, saying, "When I went campaigning {before the November election}, people told me we had to get the traffic moving . . . and we can't do that without money, so I think the people will approve it."

The list released yesterday could be amended after a public hearing on the referendum scheduled before the County Board of Supervisors on Feb. 8.

Officials said yesterday they expect the board to take its final vote on the matter the same day. The referendum would be the first special election in Fairfax County since 1978 and would cost about $300,000, officials said.

Voters have overwhelmingly approved three road bond referendums totaling $190 million since the county received authority from the legislature in 1981 to finance its roads. The last road referendum, for $135 million in 1985, was approved by 73 percent of 132,100 votes cast.

Though voters have authorized $190 million in road bonds, about $122.5 million of those bonds remain unsold, primarily because of project delays, officials said.

For example, $90 million has been authorized for work on the county's number one transportation priority -- the 35-mile, cross-county Springfield bypass -- but $85 million worth of those bonds have not been issued, primarily because of delays in design and land acquisition by the state, according to county officials.

Those delays are not only politically costly -- three incumbent supervisors were voted out of office last November, largely because not enough had been done to solve the county's transportation crisis -- but financially costly as well.

In the fall, the estimated cost of the entire bypass was increased from $250 million to more than $350 million.

The $31.2 million slated for the bypass in the proposed spring referendum would fully finance two large sections -- from the Dulles Toll Road to Rte. 50, and from Rolling Road across I-95 to Beulah Street -- that were supposed to have been paid for by the 1985 referendum.

"There was a bias {in drawing up the spring list} in terms of trying to recommend projects we can get asphalt on quickly," said Denton U. Kent, deputy county executive for planning and development.

He said that if the referendum passes, "spot improvements" could be completed this year, with "the majority of projects on the list in construction within a year to a year and a half."

The goal is to have "all the money spent" -- including unsold bonds -- and all roads on the list "operational" within three years of the referendum, he said.

"It's been made pretty clear by the board that they are more interested in asphalt at this point than grandiose schemes for the future," Kent said, adding, "We have some protections for the future, some design money for future projects {$3 million} in the referendum that should give us a leg up."

Officials said the spring road bond referendum will not interfere with county plans to have another bond referendum in November for other capital improvements.

They said the fall referendum could be for as much as $300 million to finance projects for schools, regional and county parks, storm drains, human services and neighborhood revitalization. TRANSPORTATION PROPOSALS: FAIRFAX COUNTY 1988 BOND REFERENDUM Proposal..................... Cost in Millions

1. Waples Mill Road: Extension of private sector segment to Rte. 29................................ $2.1

2. Rte. 50-West Ox interchange: Provide county share of costs.... $14.8

3. Rolling Road: Widening to four and six lanes from Burke Lake Road to Southern Railroad Bridge................ $4.2

4. West Ox Road: Widen to four and six lanes between Rte. 29 and relocated Legato Road...................... $16.0

5. Spring Hill Road: Widen to four lanes between Rte. 7 and International Drive....................... $5.4

6. Gallows Road-Rte. 29 interchange: Feasibility study and design....$1.5

7. South Van Dorn Street-Beltway interchange: Partial improvement (assumes some right-of-way dedication).......... $15.3

8. Shirley Gate Road: Widen to four lanes between Braddock Road and Rte. 29.......... $7.8

9. Rte. 236-Beauregard Street intersection: Feasibility and design of improvements.............. $1.1

SUPPLEMENTAL FUNDS (to complete existing projects):

10. Springfield Bypass North, from the Dulles Toll Road to Rte. 50............$20.5

11. Springfield Bypass South, from Rolling Road across I-95 to Beulah Street........$10.7

12. Widening Blake Lane to four lanes from Jermantown Road to Lee Highway and extending a four-lane Blake Lane to Rte. 50 at Pickett Road in Fairfax City......... $1.2

13. Rte 123-Old Dominion Drive, to provide at grade intersection improvements .......$1.2

14. Guinea Road widening to four lanes from Braddock Road to Twinbrook Road and Commonwealth Boulevard.......$1.6

15. South Van Dorn Street widening from Franconia Road to Bent Willow Drive........$1.0

OTHER TRANSPORTATION PROPOSALS:

West Ox Road (design only); Franconia Road II (design only); bonding costs; advance land acquisition/payback; spot safety and intersection improvements; advance design of projects; public transportation and vehicle maintenance facilities.............$45.5

TOTAL.............$$150.0*

SOURCE: Fairfax County Board of Supervisors.

*Project totals rounded off