IS NORTHERN VIRGINIA getting "ripped off" every time the state spreads its highway money around? That's what Fairfax County Board Chairman John F. Herrity claims. He and other county officials with ambitious road projects in mind point to millions of dollars that have been going to lightly populated areas of Virginia, while fast-growing Fairfax cols it on standby. Though this disparity is not entirely unfair, Northern Virginia has been shortchanged when it comes to political influence in Richmond: of the 11 members of the Virginia State Highway Commission, which allocates the road money, only one is from this area.

That would seem to account for a great deal of the imbalance. There are other considerations: the volume of traffic in a given part of the state is not always an accurate measure of the money needed for roads. In some rural areas, for example, construction through mountains can be enormously expensive; and in some populous areas, such as Arlington, the desire for wider roads for more automobile traffic is not so great as it is in neighboring Fairfax County.

Still, some shifting of the political weights in Richmond is in order, for Fairfax does have roads in need of improvement -- and construction costs keep rising rapidly. The reshaphing should not be limited to roads and money, either, since Virginia over the years has been unable to come up with a total transportation policy embracing highways as well as mass transit.

There happens to be a political opening for this kind of change in the next session of the state legislature. Gov. John Dalton is worried about the effect of a drop in gasoline tax revenues on available highway money, and is thinking about recommending some form of increase in the gasoline tax. But here's where there's some political leverage the other way around: some Norhern Virginia legislators are considering withholding their support for the governor's road proposals unless there are important financial assurances of money for mass transit. This should appeal to representatives of other populous areas around the state that seek transit assistance: Richmond and Norfolk leap to mind for starters.

At a time when energy conservation measures are encouraging cutbacks in car use -- and when actual figures on Potomac River crossings show a decline -- highways shouldn't be the only answer. Smart money should be going as well for other means of transporation -- and the state legislators should make that happen.