Virginia officials have reached a tentative deal with a private construction firm to build high-occupancy toll lanes on Interstate 95, hoping to ease congestion on one of the region’s worst bottlenecks, Gov. Robert F. McDonnell said Tuesday.

The agreement for $940 million is with Fluor-Transurban, the global company that is building a set of toll lanes on the Capital Beltway in Virginia.

“The project will bring congestion relief and new travel choices to Northern Virginians,” said McDonnell (R). “It will also provide an economic boost by supporting nearly 8,000 jobs over the construction period and stimulating $2 billion in economic activity.”

The 29-mile project will stretch between Edsall Road in Fairfax County and Garrisonville Road in Stafford County. Fourteen miles of existing high-occupancy lanes from Edsall Road to Prince William Parkway will be expanded from two to three lanes.

As is the case with most HOT lanes, most existing lanes will remain toll-free. Vehicles carrying three or more people will be allowed to use the HOT lanes without charge. Others can pay to access them, but tolls will change according to traffic levels.

Under the tentative agreement, Fluor-Transurban is expected to pay $843 million and the state would contribute $97 million. Construction could begin next spring, state officials said.

“With HOT lanes on both the Beltway and I-95, we will create a region-wide network of managed lanes that will enable travelers to get to and from some of Virginia’s most important employment centers and military sites,” said state Transportation Secretary Sean T. Connaughton.

Virginia also plans to invest $200 million to expand bus service in Spotsylvania, Stafford, Prince William and Fairfax counties, and add more than 3,000 spaces in park-and-ride lots.

Virginia Department of Transportation Commissioner Greg Whirley said the lanes will ease the bottleneck on I-95 near Dumfries.

“VDOT expects carpools and other travelers who use the existing HOV lanes will see faster and more reliable commuting times when HOT lanes are introduced,” Whirley said.

Although ambitious, the proposal was scaled back after Arlington County filed a lawsuit to block plans that would have extended HOT lanes inside the Beltway on I-395 to the 14th Street bridge over the Potomac.

Those heavily trafficked final miles approaching the District would have provided a cash bonanza for Transurban. The three HOT lanes, and bridges to accommodate them, from the Beltway south to Stafford would require a massive construction project. Those less heavily traveled miles of I-95 will provide less toll revenue than would have the roadway inside the Beltway.

The remainder of the project also has been met with some opposition. Stewart Schwartz, executive director of the Coalition for Smarter Growth, criticized a recent environmental assessment of the project as being “completely inadequate.”

“We believe that the HOT lanes could have a negative impact on slugging and carpooling and that they may undermine goals to reduce traffic related to the BRAC moves,” he said.

Schwartz said the state should also consider investing in transit, such as buses and Virginia Railway Express, and keeping the toll revenue “in public hands for reinvestment in the corridor.”