Virginia Gov. Terry McAuliffe’s top transportation officials have put the state administration firmly behind an extensive program to ease travel conditions on Interstate 66, a program they estimate will cost $2 billion to $3 billion.

The effort, covering the portion of I-66 between the Capital Beltway and Haymarket, is still in the planning stages, but the officials estimate that construction could start in 2017.

What could they build? The answer is, lots of stuff, but the word transportation officials use to describe such a project is “multimodal.”

State officials are very interested in adding I-66 outside the Capital Beltway to the network of high-occupancy toll lanes. This has attractions both as a way of managing traffic and as a way of financing the package of improvements.

The other potential improvements that are under study:

  • Add general purpose lanes.
  • Expand Metrorail west to either Centreville or Haymarket.
  • Build light rail west from Vienna to either Centreville or Haymarket.
  • Create a bus rapid transit system from Vienna to Haymarket, possibly with an extension east from Vienna.
  • Extend VRE to Gainesville and Haymarket.
  • Fix choke points.
  • Make it easier to get from one type of transport to another along the corridor.
  • Improve safety.
  • Upgrade the transportation communication system so that travelers have more real-time information.

Virginia transportation officials have been studying these options for several years.

On Thursday, state Transportation Secretary Aubrey Layne and other senior officials visited the Virginia Department of Transportation’s Northern Virginia headquarters to make very public declarations of support for pushing through a program of fixes. Layne said the work on I-66 is “the number one project in Northern Virginia,” and one of the most important in the state.

The McAuliffe administration, which took office in January, did not begin the effort to do something about the ghastly traffic problems on I-66, but in their statements on Thursday, they took ownership of the program to deliver solutions.

“We are dedicated to getting the project to fruition,” Layne said. Transportation officials pledged that the next phase of study — during which specific programs will be selected for development — will involve the public and be transparent. That includes the part about selecting private partners to design, build and operate some of those programs.

Layne said a public-private partnership on the I-66 program is quite likely, because of the high cost of achieving the major goals outlined in the initial study. “I don’t believe the project will come to fruition if we use only tax dollars,” he said.

The state officials said they don’t have to build everything at once. Constructing HOT lanes, for example, need not rule out the possibility of eventually extending Metrorail west in the I-66 corridor.

In fact, they acknowledged that the problems of moving people in the I-66 corridor are so complex that no one program is sufficient to address them.

Imbedded in the public statements about the importance of turning these ideas into reality is the officials awareness that what they’ve done so far is likely to be the easy part. State Sen. Chap Petersen (D-Fairfax County), who was among the public officials attending the morning event, targeted one such issue that will get a great deal of attention: Is this program going to expand the footprint of I-66 and require taking private property?

The answer is that the state hasn’t figured that out yet, but the concept under study would replace today’s single HOV lane with two HOT lanes while maintaining the number of regular lanes. Designers can try to minimize the impact of that, but it’s definitely a wider highway.

Adding toll lanes, stretching out Metrorail or building light rail are concepts that will draw their share of critics as planning continues.

“I understand not everybody is going to be 100 percent for everything,” Layne said, in what probably will turn out to be an understatement.

The fact that the administration knows there are rough times ahead and is willing to step out so publicly makes this a milestone in the decades-long efforts to ease the agony on I-66.