SHORTLY AFTER her maiden voyage to Richmond as a delegate from Fairfax County, Democrat Vivian E. Watts chatted with us during a break on the floor of the house, noting, among other things, that we had failed to list her committee assignments correctly. She had, after all, managed to land a seat on the House Finance Committee, an important vantage point.

But just how important became clear this week, when Mrs. Watts joined nine other members in a key 10-to-9 vote against a tax package that would have taken Northern Virginia to the rural cleaners--by directing all but $10 million in new gasoline tax revenues for road projects. The vote, which turned out to be an impressive coalition of urban legislators from Northern Virginia and Tidewater, was accompanied by a loud and clear message that the committee bill had not earmarked enough money to help Metro and to improve decaying urban roads.

The talk was tough on both sides. "We're bound and determined that, by God, our urban needs are going to be recognized and you just can't play this shell game any longer," said Mrs. Watts. "If we don't get this money for mass transit and for urban roads, then we aren't going to pass any gas tax." Said an infuriated Committee Chairman Archibald A. Campbell (D-Wythe), "They're going to look awfully peculiar if they go back empty-handed. Four or five years ago, I helped Northern Virginia legislators get a hefty tax for Metro . . . and this is the thanks I get."

The happy ending, of course, should be spelled "compromise"--a bill that would raise the money that is desperately needed for both roads and rails. But compromise doesn't come when one side has all the chips--and that is why the unity of the Northern Virginia delegation and other legislators who have an interest in a balanced transportation system for the state is critical. Gov. Charles Robb certainly recognizes that Northern Virginia is not some foreign territory to which aid is dispensed begrudgingly from Richmond. Similarly, the lawmakers from this end of the state should recognize the direct interest in roads that so much of Virginia has.

Rather than sulk, the two sides should talk and deal.