Pete Sklannik Jr. thinks about the sales tax proposal on the Nov. 5 ballot and envisions 50 new double-decker rail cars for Virginia Railway Express, the increasingly crowded commuter railroad that he runs.

Of the $2.75 billion generated over 20 years from bond sales financed by the tax increase, 40 percent would go to transit projects, from VRE rail cars to a trolley on Columbia Pike to maintenance and operation of Metro.

Sklannik and other transit officials said it would amount to an unprecedented level of financial support for public transportation in Northern Virginia.

Opponents of the proposal said Sklannik and VRE are a front -- window-dressing for a sales tax that is largely about building roads, enriching developers and intensifying sprawl.

"They're exploiting the public's support for transit to buy the public's support for this," said Stewart Schwartz, executive director of the Coalition for Smarter Growth, which is leading the fight against the tax. "Transit is the Trojan horse. To hear the proponents say it, you would think this is all about transit, because they don't want the public to think about the roads."

Schwartz certainly is thinking about the roads.

Highway projects would absorb 60 percent of money generated by the tax, including improvements to Routes 1, 7, 28, 29 and 234, the Fairfax County Parkway, the proposed Tri-County/Loudoun County Parkway and Interstates 66, 95, 395 and 495.

Of particular concern to Schwartz and other environmentalists is $50 million to build a Route 234 Bypass and $100 million for a Loudoun County Parkway, both of them north-south roads that would run through Loudoun and Prince William counties, opening a large rural corridor to development.

"These are outer Beltway segments," said Schwartz, adding that his views are validated by the fact that business and development interests are backing the proposal.

The November vote in nine jurisdictions will decide whether the sales tax should increase from 4.5 cents to 5 cents, generating an estimated $5 billion, more than half of it from bonds, over 20 years, according to officials.

The Northern Virginia Transportation Authority, a new agency comprising local elected officials and political appointees, would control the spending. Legislation that created the proposal requires that 40 percent of the $2.75 billion earmarked for specific projects be spent on transit. The authority would decide how to spend the remaining $2.2 billion.

"It's a funding stream for transit the likes of which we've never seen," said Katherine K. Hanley (D), chairman of the Fairfax County Board of Supervisors. "If this doesn't pass, the alternatives are very grim for transit."

Most transit funding in Virginia is paid by counties, with limited help from Richmond. If the proposal fails, transit projects will have to compete with schools, public safety and other local budgets for increasingly scarce tax dollars.

"You either have higher property taxes, cuts in other services that you provide or you don't do it. Those are the choices," said Chris Zimmerman (D), who chairs the Arlington County Board and also runs the Metro board.

If the proposal passes, the largest chunk earmarked for transit -- $350 million -- would be used to help pay local governments' share of a $3.1 billion project to extend Metro to Tysons Corner and Dulles International Airport.

Other projects include about $300 million to extend Metro along I-66 to Centreville and $225 million to build a trolley or bus rapid transit system in the Route 1 corridor from Alexandria to Prince William County. An additional $250 million would pay local governments' share of Metro's maintenance and repair costs.

Among the smaller projects are $25 million for a new bus garage for the DASH system in Alexandria and $20 million to eliminate two at-grade rail crossings in Manassas by building highway bridges over Norfolk Southern railroad tracks.

In addition, as much as 15 percent of revenue generated would go toward operating subsidies for Metro, the first local tax to be dedicated for Metro operations. The new authority would decide how much revenue is sent to Metro.

"That's of enormous importance," said John Milliken, former state transportation secretary and leader of Citizens for Better Transportation, a pro-tax group. "Metro is the largest transit system in the country without a dedicated source of funding. This is a step in that direction."

Schwartz and other environmentalists find themselves in the unusual position of arguing against a proposal that would fund about a dozen transit projects, an issue they typically support.

"These outer bypasses will undermine any transit investments," Schwartz said, adding that he wouldn't back the tax even if all proceeds went to transit projects because Fairfax, Loudoun and Prince William counties have not changed zoning laws enough to shape growth and prevent sprawl.

"To simply, blindly, expand capacity, whether road or rail, with no connection to change in design of communities and land use is a complete waste of money," he said.

"Transit is the Trojan horse," says Stewart Schwartz, right, of the Coalition for Smarter Growth.