Virginia Gov. Bob McDonnell cut the ribbon Tuesday for the opening of the state's new Beltway Express lanes -- a $1.7 billion project that officials say will speed the flow of traffic along the entire highway and make commuting less of a pain for thousands of drivers.

"Everyone in the region will benefit from this project," Fairfax County Supervisor Jeff McKay said at the dedication in Tysons Corner. "The community also benefits from this project that will support our region's economic prosperity, unclog one of our busiest commuter routes in the country and provide better access to our business hub in Tysons Corner."

The 14 miles of toll lanes -- two in each direction -- will officially open Saturday. They stretch from Springfield to just north of the Dulles Toll Road. Drivers will be charged more at times of peak traffic, keeping a limited number of cars in the lanes to avoid jams. The fees can range from 20 cents a mile to $1.25 a mile, or even more. Officials estimate the average trip will cost between $5 and $6. Carpoolers can ride for free in the lanes with a new device called E-ZPass Flex, and all other drivers will need an E-ZPass to use the booth-free lanes, or face higher fees via mail.

McDonnell credited a decadelong, bipartisan push to build the lanes, as well as private-sector innovation, for the traffic relief expected from the Beltway expansion -- something considered too difficult and expensive for decades, he said.

"So many said expanding the Beltway was just an impossible task," McDonnell said. "It's pumped billions of dollars into the economy and put thousands of people to work. It will begin the process of undoing some of the gridlock up here, giving travelers a real choice."

Australian toll road developer Transurban partnered with construction giant Fluor to build the $1.7 billion lanes, in exchange for most of the toll revenue for the next 80 years. The state paid $409 million, in a "public-private partnership" that officials said would become a model for how Virginia would have to continue building big-dollar construction projects on shrinking budgets.

"If you want to get projects done, and given the costs involved, you've got to look for ways to bring in the private sector," said Virginia Secretary of Transportation Sean Connaughton.