IN A MISGUIDED and incredibly ill-timed reprise of a destructive proposal, Fairfax County Board Chairman Herrity is again charging that Northern Vigrinia's latest gasoline tax is somehow "unfair" because he doesn't like the way the revenues from it are being divided up. His after-the-fact bleat refers to a tax that took years of careful negotiations among local and state officials to get through the general assembly, as a way to help pay for critical Metro bus and rail expenses. After it finally won approval in Richmond, it was up to the Northern Virginia Transportation Commission to agree on an allocation formula -- which it did -- and which, for the narrowest of political reasons, Mr. Herrity now wants to wreck.

His rationale? Because Fairfax has proportionately more service stations with heavier traffic than the close-in suburbs of Arlington and Alexandria, it collects more revenue than it gets back from the regional tax -- and never mind that all Fairfax supervisors were aware of this last winter when it was accepted as part of the compromising necessary to win enactment of the tax.

Even if this weren't the history of the allocation formula, Mr. Herrity's count-the-gas-stations idea is silly. If this is good thinking, why doesn't he carry it further by requiring every station-owner to find out and list the home jurisdiction of very motorist who pulls in to buy gas? Or perhaps Mr. Herrity would prefer to give the biggest share of money in his county to the Fairfax district with the most gas stations; or maybe it should go to the neighborhood block that pumps the most unleaded every week.

There are certain important services that Northern Virginia's governments undertake together for the mutual benefit of all their residents. This is one -- and a carefully achieved one it is -- and Mr. Herrity should have the regional vision and understanding to recognize that.