All along the route of Virginia's first commuter rail service, scheduled to begin operating in October 1991, developers are rushing to buy land and position themselves to profit from an economic boom expected to follow the trains.

Developers and planners expect the 95-mile Virginia Railway Express system, which roughly parallels Interstate 66 and Interstate 95, to open communities on the edge of the metropolitan area to residential development along the rail lines from Manassas and Fredericksburg and to stimulate office development around Union Station in the District and in Alexandria and Arlington.

"The corridor is just going to boom . . . . You know your residential growth will be supported by the commuter rail," said Cindy Craven, marketing director for Charter Communities, which is building several projects near planned stations in Stafford County.

The commuter rail system also could help solve what the Metropolitan Washington Council of Governments calls the region's number one problem -- the shortage of affordable housing -- by providing reliable public transportation between downtown Washington offices and the fringe counties where less expensive homes are built.

For the first time, downtown workers who buy housing in Manassas and Fredericksburg, situated 35 and 60 miles from the District respectively, will have alternatives to the grueling three- and four-hour daily treks on congested highways.

Developers expect house buyers to jump at the chance. Meanwhile, the local governments responsible for providing services, while grateful for potential growth in their tax revenue, wince at the prospect of keeping up with development that is crowding schools and clogging roads.

Experts point to the success of Metro, which has spurred high-density development along its paths since opening in 1975, as an indication of how a rail transit system can play a vital economic role in shaping a community. While commuter rail is expected to generate less-intense development, it is projected to make a difference.

Initially proposed in the mid-1970s, commuter rail first got serious attention from Virginia officials about five years ago. However, the problem of protecting the freight railroads that own the tracks from liability in case of an accident delayed the start-up. The final barrier for that problem was cleared earlier this month when President Bush signed legislation exempting Consolidated Rail Corp. from damages.

Before the rail service is scheduled to begin, in 15 months, 38 cars and 10 locomotives must arrive, stations and parking lots must be built and schedules and fares -- estimated to range from $5 to $8 round-trip -- must be set.

The two rail lines are expected to serve 4,000 daily round-trip passengers -- the equivalent of one lane of rush-hour traffic on I-95, but minuscule when compared with the total number of commuters. COG predicts 697,000 Northern Virginia residents will be commuting by 1995, and those numbers don't include the counties around Fredericksburg.

Supporters predict Virginia Railway Express eventually will serve many more commuters. For example, the Maryland Rail Commuter Service, which links suburban Maryland with Washington and Baltimore, doubled its ridership between 1987 and 1990 to 14,865 passengers daily.

"Commuter rail can play a significant role in helping to alleviate the commuter crisis," said Robert Gladstone, president of Quadrangle Development, which is building offices near Union Station. "It will open up new corridors."

Virginia's commuter rail -- one of only eleven systems in the country -- will be the first major rail service to begin operation since Miami and Fort Lauderdale started one in 1985, said rail planner Stephen Roberts.

In Northern Virginia, experts predict the rail system's most visible effect, at least in the early years of its operation, will be to ignite suburban residential growth near the stations in the Fredericksburg area, Stafford County and western Prince William County.

In Stafford, the race for undeveloped land is underway. Most large open tracts have tripled in value during the last two years, said Stafford real estate assessor James Guy.

Joseph E. Torrice's 34 1/2 acres less than a mile from Stafford's planned Leeland station were assessed at $45,900 in 1988, but he sold the land in May for $275,000 plus closing costs. Said buyer Christian P. Kaila, who plans to build homes on the property: "If there was no chance of commuter rail, we wouldn't have done it."

In 1988, NVLand bought 195 acres near what will be Stafford's Brooke station for $625,000 -- more than three times the land's assessed value -- precisely because it expected a station to be nearby. The company plans to build houses in the next two or three years, said Vice President R.D. Entsminger.

Hazel/Peterson Cos. has offered to build a commuter rail station in its proposed 651-home development in eastern Prince William County. One stop to the north, Virginia Properties intends to give -- or rent for a nominal amount -- 16 acres to Prince William for a station as part of its Belmont Center office and residential complex.

Newspaper ads for homes in Stafford, Spotsylvania and Fredericksburg have been saying "commuter rail coming soon" for several years. "Eighty percent of the homes we sell are to {people} working in Crystal City and Washington . . . and the buying public is a little apprehensive about that I-95 corridor" said Richard D. DiBella, vice president of Winchester Homes' Northern Virginia operation.

These and other projects near planned rail stations stand in contrast to the general slowdown in construction. The Hazel/Peterson project, for instance, is one of a handful of large residential rezoning requests to come into Prince William's planning office in the last six months.

Officials in Fredericksburg and the counties farther south worry the rail service will cost too much and turn their jurisdictions into bedroom communities with overburdened roads and schools.

Officials and developers in the District, however, view commuter rail as an undeniable benefit, primarily because it will enlarge the potential labor pool for downtown businesses. In 1987, 83.9 percent of the metropolitan area's 2.7 million civilian workers lived in the suburbs, and some commercial developers say they have lost tenants to suburban office parks because of the traffic woes associated with getting downtown.

With encouragement from local officials, the rail service's suburban stations could create commercial identities for previously unremarkable patches of open land if local officials zone the areas around the stations for that kind of growth, planners said. Unlike most regional commuter rail systems -- including the one in Maryland -- Virginia's system will use few established stations.

So far, however, local planners have done little to prepare for commuter rail. Prince William and Fairfax are updating their comprehensive land-use plans and neither has taken in-depth looks at the station areas. Prince William Planning Director Doug James said he prefers to see exactly what commuter rail will do before modifying the county's land-use plan.

Manassas Park is the exception. Officials in Virginia's smallest city hope to use their commuter rail station to change the city's character. Manassas Park has no central business district, only a strip of stores on Route 28, so officials hope to find a developer to build a shopping center on city-owned land around the rail station.

What Commuter Rail Organizers Have Already Done

Signed an agreement with Amtrak to operate the service.

Signed agreements with three freight railroads to use their tracks.

Selected 17 stations to open in October 1991.

Secured passage of federal liability legislation, which made D.C. service possible.

Ordered 38 passenger cars, each seating 115, and 10 locomotives.

Hired Thomas R. Waldron to manage the rail company.

Steps Still To Be Taken

Purchase ticket dispensers, which will operate by credit cards.

Set fares and schedules.

Build parking lots and stations, and acquire land for some stations.