ADISAPPOINTING, if predictable, quirk of Virginia's gubernatorial campaign is that the two major candidates insist on ignoring the dimensions of the state's most urgent problem: its pitifully clogged highway system and inadequate mass transit network. Maintenance and expansion needs have been neglected for so long that the most definitive study says they will cost an extra $108 billion over the next 20 years -- and that's additional expenditures, beyond the $95 billion the state already expects to spend by 2025. Where in the world would Virginia find the money, or even half that much? Neither Republican Jerry W. Kilgore, the former attorney general, nor Democratic Lt. Gov. Timothy M. Kaine is saying, doubtless because the answer must include the politically suicidal words "taxes" and "tolls."

Fortunately, elder statesmen and long-shot candidates are not bound by such electoral niceties. Former governor Gerald L. Baliles and state Sen. H. Russell Potts Jr., an independent candidate for governor, have injected a note of realism into the debate at just the right moment -- while voters have nearly two more months to cross-examine Mr. Kilgore and Mr. Kaine.

Mr. Baliles, now a lawyer in private practice, has proposed a plan that would raise $1 billion a year by charging tolls on the state's extensive interstate highway system, including Interstates 66, 95 and 395 and the Capital Beltway in Northern Virginia. As he conceives it, the tolls, at 38 points along Virginia's interstates, would average 85 cents (probably less for commuters and frequent users, and more for trucks) and would charge drivers electronically, without the need for stop-and-go toll booths. A Northern Virginia commuter working in Washington might have to pay as much as $3 or $4 a day in tolls, depending on his specific route and point of origin. Mr. Potts has endorsed the former governor's tolls plan as well as an additional $1 billion a year in new revenue for transportation through higher taxes on sales, income and cigarettes. Each plan has its advantages and obstacles, but they deserve to be taken seriously.

Tolls would hit plenty of people's wallets, but they make sense on several levels. They would ensure that the costs of maintaining and improving the state's highway system are borne by its users, including drivers from out of state. And, as Mr. Baliles points out, his plan offers the hope for relatively quick and efficient progress: Sustained over 12 or 15 years, an annual infusion of $1 billion in transportation-only funds could pay for a long list of major projects. In Northern Virginia, those projects might include widening I-66 and adding lanes to the Beltway, I-95 and I-395.

Unlike Mr. Potts's plan, which would raise revenue from multiple sources, the Baliles approach is one-dimensional, relying exclusively on tolls. It's an open question whether the state could win the necessary permission from the federal government to charge tolls on interstates. But the fact is that more tolls are already integral to Virginia's driving future; they are planned for practically every major highway expansion project in the state. Mr. Baliles himself is part of a consortium bidding to buy and upgrade the existing Dulles Toll Road for $1 billion in exchange for toll revenue. Tolls are an excellent starting point for a serious, if belated, discussion of how to fix Virginia's sclerotic highways. If only the major gubernatorial candidates would join in.