WHERE DO YOU think the greatest population explosion in this region might be between now and, say, the year 2010? If you said Prince William County and Loudoun County, that's what the Metropolitan Washington Council of Governments has been saying. And in Prince William, the people are saying this means roads -- as quickly and as economically as possible. That is why the county's board of supervisors has just voted unanimously to place a bond referendum on the ballot this fall. As Prince William's neighbors in Fairfax County can attest with road-weary authority, bonds are the way to go -- if you're talking about going by car, truck or bus. That's a new message in Prince William, where voters in the past have rejected bond issues; and therein lies a heavy sales job for every supervisor.

Most of the money from the proposed bond issue -- $30 million -- would be for road improvements. Another $12 million would be for a new police and fire training center and for other capital projects. With the county staring at a projected 64 percent increase in population over the next 25 years, residents cannot look to the state for adequate assistance, nor should they try to pay for everything through increased taxes.

One forward-looking coalition has been plugging for the local road bond issue for some time. The Businessmen's Round Table has formed Citizens for Better Roads, Inc., under the chairmanship of Robert C. Wilcox, who points out that the bond issue is a bipartisan economic development issue that needs support right away since road improvements take years to complete. The group also notes that Fairfax has been able to decrease taxes because improved road conditions have allowed the county to attract revenue-generating employment centers.

"Chronologically, we are about 12 years behind Fairfax in our development," says Supervisor G. Richard Pfitzner, "but in attacking our problems with progressive thinking, we are only three or four years behind. We are learning from the lesson of our more urban brethren."