NO ONE HAS ever accused Fairfax County Board Chairman John F. Herrity of being subtle when it comes to public policy questions -- and his characteristic bluntness has just reaped a dividend for the county's fast-jamming road system. Mr. Herrity advised key property owners along the Route 28 corridor just east of Dulles International Airport that if they want that strip widened in time to accommodate an expected development boom there, they'd better put up some money of their own. They have taken his advice and agreed to pay a surtax that would help finance the road-widening. The idea is not unlike "impact fees" that local governments negotiate, but a surtax can produce the money far faster and with less red tape.

Under a tentative agreement worked out the other day, eight developers owning nearly 2,000 acres of approximately 5,000 acres along the Route 28 corridor have endorsed the idea and have pledged to sell it to the remaining property owners. As Mr. Herrity notes, these companies are primary users of the road network and should help defray costs of major highway improvements. The Route 28 corridor is not only the focal point for some big- time commercial projects but is also the area in which Virginia's Center for Innovative Technology will be established -- no doubt attracting still more business to this strip.

The widening would be from two lanes to six between the Dulles Access Road and Route 50. County officials hope to commit the developers to a surtax of up to 20 cents per $100 of assessed valuation, though so far they're talking about a tax in the neighborhood of 10 cents. Mr. Herrity emphasizes that neither the idea in general nor the surtax in particular would apply to residential property.

On Monday, Mr. Herrity will ask the supervisors to request special legislation from the General Assembly to authorize this financing plan -- and if they want it to work at all well, they should act now. The state legislature will be meeting in special session in September, and any start-up money Fairfax might secure from the state had best be sought then. And if you take a good look down that corridor beyond the Fairfax line, you'll see a message for the the neighboring government: Loudoun, please copy.