When a place grows and families add children, the government builds new schools. What could be more obvious? Cast your eyes across the burgeoning burbs and wherever you see thousands of new houses, you'll generally find new fire stations, hospitals and, of course, shopping centers galore. Makes sense.

But population growth rarely spurs a similar expansion of transportation infrastructure. So hundreds of thousands of new residents in Loudoun and Prince William counties, in the outer portions of Montgomery and Prince George's counties and on into Southern Maryland find themselves crawling along narrow streets designed for farmers -- suburbanites trapped in a rural road system.

When roads are built first, before homes rise from former farmland, everything works reasonably well. Witness the explosion of growth up Montgomery's I-270 corridor, where Metro's Red Line helps relieve traffic, or along the Dulles Greenway. But when development comes first, we are sentenced to paralysis.

Virginia's next governor, Tim Kaine, aims to break open the transportation logjam. In a state that foolishly limits governors to a single term, four years as a lame duck governor isn't enough to take on such a massive task. But Kaine, flush with the sweet adrenaline of victory and eager to build on Gov. Mark Warner's success in putting the state's finances in order, boldly proposes to get it done in his first year.

But what is "it?" As I watched Kaine conduct a town meeting on transportation in Manassas on Tuesday night, that basic question kept pushing aside questions about process. Even if you could get beyond the core dilemma over money -- do you raise taxes to build transit and roads, or do you insist, as Northern Virginia voters did in the 2002 transportation referendum, on doing everything with existing resources? -- you'd still lack agreement on what it means to fix traffic.

On this fourth of more than a dozen stops in his all-transportation tour, Kaine listened as dozens of residents, politicians, road lobbyists and smart-growth advocates instructed him that if you'd just [fill in the blank], you'd go down in history as the Transportation Governor. The blanks were a bundle of contradictions: rail to Dulles, build highways, widen I-66, don't widen I-66, double the density of Tysons Corner, don't do that, build big around Metro stations, never ever do that, and so on.

Afterward, Kaine told me that he'd heard "a diversity of opinions, which is another way of saying no consensus." He laughed. (Get used to such frank talk; the Warner years of cautious rhetoric are over.) "My job is to hear everything I can, try to decide what's best and promote it."

Longtime road advocates like Bob Chase, who still believes that Northern Virginia requires a new Potomac River crossing and an Outer Beltway, says all Kaine needs is a big show of political will. "Look at Maryland," he says. "The intercounty connector," the proposed highway linking I-95 to I-270, "went from dead in the water to number one priority, and the only change was the political will of Governor Ehrlich."

Surprisingly, Kaine agrees. Political will "is a huge portion of it," he says. He seems inclined to widen 66 inside the Beltway and push the extension of Metrorail through Tysons and on to Dulles Airport.

That will mean standing up to powerful interests. The reason schools, hospitals and fire stations get built in high-growth areas is that the interests of the people who live right there happen to coincide with the broader good. Transportation divides people differently: Everybody wants the roads they commute on to be massive, but no one wants the little byway near their house turned into a 12-laner.

Those who'd benefit from widening 66 in Arlington live in Prince William. Many Arlingtonians would just as soon see the road demolished. Our system is weighted toward those who live near a project. How do you build support for something the locals loathe?

If the people are already there, you can't build it. That's the lesson of the past 40 years. Bob Ehrlich has spent his entire term trying to disprove that on the ICC in Montgomery and Prince George's, and he may yet succeed. Tim Kaine says he's going to do it in a matter of a few months. Just as soon as he can figure out what "it" is.

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