One road. One solution. Two plans.

That’s the approach the Virginia Department of Transportation (VDOT) is taking with its latest attempt to rectify ever-increasing congestion on Interstate 66, Northern Virginia’s primary east-west corridor into Washington, D.C.

The solution is the increasingly popular concept of High Occupancy Toll (HOT) lanes, a revenue-generating system of capacity expansion that VDOT has already implemented along the western portion of the I-495 Beltway, and on I-95 from the Beltway south to Stafford County.

Two plans are needed because I-66 is, in many ways, a different road on either side of the Beltway.

From a construction perspective, the 22-mile “outside” segment between the Beltway and the far western suburban hub of Gainesville is “easier” to tackle.

For most of that route, VDOT has sufficient right of way to revise the existing east- and westbound configuration of four regular lanes, one of which is reserved for High Occupancy Vehicles (HOV) during rush hour, into three regular lanes and two HOT lanes. HOV motorists would have free use of the HOT lanes. And there’d still be enough room for an eventual extension of Metrorail’s Orange Line or other transit system.

Only in the more densely populated Dunn Loring area near I-66’s junction with Beltway will VDOT need to acquire adjacent land for the expansion, but the agency claims that will require the condemnation of only five existing residences in the area.

Construction of the “outside” HOT lanes is slated to begin in 2017, though VDOT has yet to decide whether to pursue a full-fledged P3 as it did with the I-495 and I-95 projects, or assume a larger share of the project funding in order to retain the toll revenue. That decision is due this December.

Inside the Beltway, I-66 becomes a bit more complicated, and not because of that segment’s closer proximity to the federal government, as some wags might suggest. The jurisdictions along that 10-mile stretch have long opposed any move to add capacity to the inside segment. In fact, it was only the dedication of I-66 as HOV-only during rush hour that helped get that segment built at all in the 1970s.

That restriction remains in place today, much to the frustration of single-occupancy motorists who must find other routes into DC once they reach the Beltway, or time their trips for non-HOV hours.

Even without the resistance to expansion, more dense development on both side of I-66 inside the Beltway leaves few options for widening the highway beyond its existing four lanes.

VDOT plans to convert I-66 into HOT lanes in 2017, with HOVs continuing to receive their “free ride,” though the minimum number of passengers will be bumped up from 2 to 3 passengers in 2020. VDOT is counting on congestion pricing to help prevent the existing limited amount of pavement from being overwhelmed with new users. Some have criticized that idea, as toll avoiders may simply reschedule their trips as they currently do with the HOV restrictions, bogging down I-66 for much of the day and evening.

Efforts to appease the jurisdictions may lead to the addition of new lanes at some point, but not before 2040. In the interim, VDOT has promised to make improvements to some of the area’s major highways. Again, some portions of the road simply have no room for widening without large (and expensive) acquisitions of land or, in the case of the Rosslyn Tunnel near the Potomac River, some major (and expensive) infrastructure work.

This duadic approach to corridor congestion relief may sound complicated, but it’s the rare suburban-to-urban infrastructure project that isn’t. For a variety of reasons, I-66 just happens to have more than others.