Traffic on Interstate 66 near Vienna. (Karen Bleier/AFP via Getty Images)

A plan to turn Interstate 66 inside the Capital Beltway into a toll road during morning and evening rush hours has opened up sharp divisions between Virginia Gov. Terry McAuliffe’s administration and a bipartisan group of congressional representatives and raised broader questions about how to solve one of the region’s most persistent and infuriating bottlenecks.

A key point of contention is how to handle what Virginia Department of Transportation officials said is the far-reaching evasion of carpool regulations on I-66, which requires vehicles traveling on the road inside Interstate 495 during rush hours to have at least two people.

But nearly 35 percent of morning rush drivers heading east and nearly half of evening rush drivers going west violate those rules, according to VDOT. And that, it said, adds to the crowding — and the need for a toll system.

Under the proposed tolling system, cars with three passengers could drive free.

Rep. Gerald E. Connolly (D-Va.) said he was taken aback by the tone and substance of a briefing by Virginia Transportation Secretary Aubrey L. Layne Jr. and other officials earlier this week on Capitol Hill. Connolly said that the briefing had an air of finality to it that seemed to indicate VDOT was barreling ahead with plans for a toll road even though that had not been sufficiently debated.

Layne discussed various elements of a multibillion-dollar state effort to improve life for drivers along nearly 35 miles of congested I-66.

“I have no doubt they were hoping this project would stay under the radar,” Connolly said.

Although Connolly said he is reserving judgment on key parts of the plan, including the toll-road proposal, he made it clear that such a “radical transformation” of a key regional road is far from a done deal, despite what he said state officials seemed to believe.

“It cannot be a fait accompli,” Connolly said. “I’ve worked with Democrats and Republicans in Richmond for more than 20 years and . . . I have never seen as little communication and outreach as I have with this one.”

Brian Coy, a spokesman for McAuliffe, rejected that assessment.

“The idea that there has not been significant outreach, both to the congressional delegation and members of the public on this project, is not supported by the facts. There have been right around 30 public meetings” about I-66 this year, Coy said. He added that there have been “numerous communications, meetings, briefings, phone calls,” as well as e-mail correspondence, with Connolly and his office on the project.

“If there are misunderstandings about this project, it’s certainly not for lack of outreach or availability,” Coy said.

Coy did acknowledge that there may be room for “policy disagreements.”

“That’s to be expected for a project of this size,” he said. “Secretary Layne and the governor have repeatedly stated that this project is at its earliest stage of planning. There have been and will continue to be ample opportunities for all stakeholders to be heard.”

There are two major components of the proposed I-66 improvements. Dozens of miles of new lanes would be built outside the Beltway, potentially as part of a public-private partnership. A private company could help pay to build them and take toll revenue for decades.

Inside the Beltway, the existing road would get a toll system.

The tolls would fluctuate according to the number of cars on the road, which in theory would allow free-flowing, if costly, travel on a road where such a luxury is often impossible to obtain. Such a dynamic pricing system is also used on paid express lanes along Interstates 95 and 495.

Opponents, though, say that adding tolls to an existing road like I-66 inside the Beltway — as opposed to using them to fund construction of new ones — will in essence result in taxpayers having to pay for the road twice.

VDOT says the I-66 toll revenue inside the Beltway would pay for the toll system itself and also be used on a series of transit initiatives, potentially including better bus service and Metro station fixes as well as bike and pedestrian improvements.

The carpool, or high-occupancy vehicle, system on I-66 within the Beltway is an awkward arrangement from a decades-old compromise that allowed the road to be built despite opposition in Arlington County. Back in the 1970s, when the road was approved, the carpool rules required four passengers. That was reduced to three and then, under pressure from members of Congress, to two.

In a letter to Layne, Connolly joined with Reps. Rob Wittman (R-Va.), Don Beyer (D-Va.) and Barbara Comstock (R-Va.) — who all represent areas in Northern Virginia along the road — in declaring that parts of the I-66 plan were “unacceptable.”

Given the high percentage of people evading carpool rules, better enforcement should be tried first, they said.

“With regard to the proposed move to HOV-3 inside the Beltway by 2017, we are very concerned by the accelerated time­table and are not convinced that other options to improve traffic flow, including stronger enforcement of current HOV violators, have been fully explored,” they wrote. “It seems that simply enforcing the existing HOV restrictions would significantly improve traffic flow inside the Beltway.”

Fines for violations start at $125. A fourth violation in five years would bring a $1,000 ticket. But Virginia State Police say troopers lack the manpower to keep up with the torrent, which is made even more difficult because those headed for a flight at Dulles International Airport are excluded.