The I-495 Express Lanes provide a faster passage at a variable price. (Michael S. Williamson/The Washington Post)

The $1 billion transportation deal Virginia officials announced this week to add more toll lanes on Interstates 95 and 495 also will address a major bottleneck for southbound traffic at the Occoquan River crossing between Fairfax and Prince William counties.

The project was at the center of months-long negotiations between the state and Transurban, culminating with Tuesday’s announcement of a plan that allows the Australian company to expand its toll operations in Northern Virginia and solidify its decade-long relationship with the state.

Transurban will extend the 495 Express Lanes to the American Legion Bridge and begin construction of an additional 10 miles of the 95 Express Lanes to Fredericksburg. The company also will build a ramp from the 95 Express Lanes at Opitz Boulevard to connect to shopping and medical facilities in Woodbridge.

In exchange, the state will be allowed to build a southbound lane to ease the Occoquan bottleneck. Additionally, Transurban will pay the state a concession of $277 million, a sum announced last year, to help cover the costs of a bridge over the Rappahannock River and other improvements. Officials said Transurban will also give the state a payment of at least $54 million in unanticipated project savings. Virginia officials said that money will be used to help pay for the new Occoquan auxiliary lane.

Transurban had opposed construction of the lane citing a stipulation in its original contract that forbids Virginia from building general travel lanes where Transurban operates high-occupancy toll lanes. If the state had tried to build the extra lane without a deal, it could have potentially faced millions of dollars in penalties.

“The Commonwealth was clear on our position that the construction of an auxiliary lane would not constitute a compensation event. Transurban was clear on its position that this project would constitute a compensation event. In the end, we agreed not to debate the issue over the next several decades,” said Amy Wight, Virginia’s assistant transportation secretary. “Avoiding what could be a lengthy and costly legal battle is in the interest of both parties and of Virginians, and the decision was to move forward with this specific improvement.”

The Virginia Department of Transportation will build and maintain the new southbound lane, a $30-million project that will connect the southbound Route 123 ramp onto I-95 with the off-ramp at westbound Prince William Parkway. It is the smallest of the four projects Gov. Ralph Northam (D) announced Tuesday.

In a Jan. 29 letter, Transurban confirmed to the state that the 95 Express Lanes “will not seek to recover compensation from VDOT in connection with the Occoquan Auxiliary Lane.” Jennifer Aument, president of Transurban’s North America operations, said in an interview that the company had no intention to seek payment from the state, but was focused on “working out a solution.” She said in exchange for allowing VDOT to move forward with the improvement, Transurban was allowed to build the ramp at Opitz Boulevard, where she said customers want better access to the shopping center.

“We think that’s a great outcome for everybody,” Aument said.

Transurban will design, build, operate and maintain the Opitz Boulevard ramp, an investment of $50 million, as well as the two other much bigger projects: 2½ miles of express lanes to the north to the American Legion Bridge at cost of $550 million and the 10-mile expansion of the 95 Express Lanes to Fredericksburg at a cost of $400 million.

In Fairfax and Prince William, officials celebrated the Occoquan lane project, citing an impossible situation with the Transurban contract and a growing need to ease traffic.

“This issue has been on everyone’s radar for about 10 years now and the primary obstacle to doing anything was the Transurban contract,” said state Sen. Scott Surovell (D-Fairfax), who along with state Sen. Jeremy McPike (D-Prince William) lobbied the governor to put the Occoquan improvement on the negotiating table. “The only way that the Occoquan bottleneck was getting fixed was through the governor negotiating with Transurban. That was the only way.”

The construction of the auxiliary lane is expected to take place within the next three years, Surovell said. The project will improve safety along a stretch of highway that narrows from five lanes to three as it crosses the river and enters Prince William County.

“The bottleneck is so severe that many people start veering off the I-95 area and onto our secondary roads to find another route to their destination,” Prince William Supervisor Ruth Anderson (R-Occoquan) said. “It really hurts the quality of life for our families.”

Virginia’s decision to partner with Transurban on these projects builds on the decade-long relationship with the company that built the 495 Express Lanes, the first high-occupancy toll lanes in the Washington region, as well as the 95 Express Lanes. The expansion will grow the company’s presence as the largest private operator of toll lanes in the region, with more than 45 miles of express lanes opened within the past six years.

The state itself runs 10 miles of toll lanes in the inside-the-Beltway portion of Interstate 66, which began operations a year ago. Another 22½ miles of toll lanes on I-66, outside the Beltway, are under construction by I-66 Express Mobility Partners, a consortium of global companies including Madrid-based Cintra. Transurban made an unsuccessful bid for that $3.7 billion project — which is scheduled for completion in 2022.

Transurban has a 75-year concession to operate the 95 and 495 express lanes and collect the toll revenue.

“Our partnership with VDOT is active every day, minute to minute hour by hour,” Aument said.

“We are co-operators of the 95 corridor. Our teams are working together every hour of the day to clear incidents, to ensure that we are coordinating on major weather events and travel disruptions,” she said. “It’s a shared commitment.”