Virginia Gov. Ralph Northam announced Tuesday that the state has signed an agreement with Transurban to extend the 495 Express Lanes to the American Legion Bridge, a project that will add nearly three miles to Virginia’s system of high-occupancy toll lanes and provide a critical link to the region’s growing toll network.

The state also is expanding the Interstate 95 toll lanes to Fredericksburg and adding a ramp and auxiliary lane in the Woodbridge area as part of new agreements with Transurban, Northam (D) said. The Northern Virginia projects amount to more than $1 billion in investments in transportation over the next five years, the governor said.

“These four significant projects on I-495 and I-95 will reduce congestion, improve safety and will be catalysts for economic growth,” Northam said at a morning news conference. “My administration is committed to creating opportunity for Virginia families and businesses in every corner of the Commonwealth, and that requires having a safe, reliable transportation network.”

Northam said the deals come after months of negotiations with Transurban, which funds and operates the 95 and 495 Express Lanes. The Australian company is also overseeing construction and operation of the 395 Express Lanes, converting an eight-mile stretch of Interstate 395 high-occupancy vehicle (HOV) lanes into toll lanes.

As part of the deal, Transurban will spend more than $550 million to complete the 2.5-mile extension of the 495 Express Lanes north to the American Legion Bridge, a project that officials say will reduce congestion in that stretch of the roadway known to be one of the biggest bottlenecks in the region, and help lessen cut-through traffic in nearby neighborhoods.

The highway widening will complete the last leg of a tolling system on Northern Virginia’s portion of the Capital Beltway and connect to Maryland’s proposed toll lanes on its side of the Beltway, Interstate 270 and the Baltimore-Washington Parkway.

The Virginia project will include connections from the Express Lanes to the George Washington Memorial Parkway and the Dulles Toll Road. When complete, four general purpose lanes and two new Express Lanes will run in each direction of the Capital Beltway along that stretch. With no public funding by the state, the Express Lanes network will be extended to the Maryland border.

Along I-95, Transurban has agreed to build a new reversible ramp — a $50-million project — connecting the 95 Express Lanes at Opitz Boulevard to enhance access to the popular Potomac Mills shopping center. The Virginia Department of Transportation will build and maintain a new southbound auxiliary lane on I-95 in Woodbridge to address a traffic bottleneck at the Occoquan Bridge. The Occoquan auxiliary lane, a $30-million project, will connect the southbound Route 123 ramp onto I-95 with the off-ramp at westbound Prince William Parkway, officials said.

Virginia transportation officials said contract negotiations have been finalized for the extension of the 95 Express Lanes to Fredericksburg, a project announced by former governor Terry McAuliffe (D) last year. Northam said a new agreement will get construction started this year.

Transurban President Jennifer Aument said at the morning briefing that the company is ready to get to work on the projects, calling them “transportation solutions” that ensure Virginians have a better commute. She said the commutes of thousands of people in the corridors have improved with the opening of the 495 and 95 express lanes within the past six years.

“It was one of the most congested roadways in the country and now we have millions of customers who are saving as much as 90 minutes a day on their commutes across the network in Northern Virginia,” Aument said. She said more than 100,000 carpoolers and more than 800 buses use the toll network daily.

“We celebrate that success and we look forward to tomorrow,” Aument said. “We are going to roll up our sleeves … We are going to get out into the community, work with local stakeholders and local residents and put together the projects and the improvements that will best serve the community.”

Local officials and business leaders welcomed news of the projects, which they say will reduce congestion, improve safety and be catalysts for economic growth. They also are viewed as critical to advance a vision for a more interconnected network of toll lanes in the greater Washington region.

“With nearly 20 percent of the region’s commuters traveling across state borders and the advancement of the Express Lanes network in Virginia all the way to the American Legion Bridge, it becomes more important that we think about how Maryland and Virginia’s toll network sync up and provide a seamless integrated and efficient system for the commuters to be able to connect from home to work on a daily basis,” said Joe McAndrew, director of transportation policy for the Greater Washington Partnership.

Maryland’s plan to add toll lanes on its side of the Capital Beltway, and on I-270, remain in the planning and environmental review stage. McAndrew said with Virginia now officially moving forward on the south side of the bridge, the expectation is for Maryland to advance its project to coincide with Virginia’s timeline, and for both jurisdictions to work out a plan to improve or replace the American Legion Bridge — which belongs to Maryland — and is the region’s worst bottleneck.

The widening of the Capital Beltway to include toll lanes to the Maryland border is viewed as critical to address the traffic congestion in that part of the region. There are as many as 240,000 daily crossings on the American Legion Bridge, where congestion is the worst, according to Virginia transportation officials, and traffic backups routinely extend from the bridge in Maryland to Tysons in Northern Virginia — even outside rush hours. In Prince William County, drivers encounter as many as 23 traffic jams daily and backups that stretch more than six miles, Rep. Gerald E. Connolly (D-VA) said, calling the area to be “by some measures, the worst traffic ‘hot spot’ in the country.”

“That is a dubious distinction we do not want to associate with Northern Virginia,” Connolly said. “This congestion costs people time with their families and money out of their pocket. This investment is long overdue.”

Environmental studies are underway for some of the project, including the 495 extension design plans. Construction could begin as early as 2020, officials said.

The projects will deliver the next major milestone in the state’s vision to create a network of more than 90 miles of HOT lanes in Northern Virginia by 2022. In the I-95/395 corridor alone, there will be 50 miles of toll lanes from the Washington line to Fredericksburg.