Hogan’s $9 billion plan would add four toll lanes each to Maryland’s portion of the Capital Beltway and to I-270 from the Beltway to Frederick. It would also widen the Baltimore-Washington Parkway by four toll lanes. (Jose Luis Magana/AP)

Maryland Gov. Larry Hogan’s proposal to add toll lanes to three of the most congested highways in the Washington suburbs reaches beyond similar proposals that stalled over the years after being deemed too expensive or disruptive to adjacent communities.

Hogan’s $9 billion plan would add four toll lanes each to Maryland’s portion of the Capital Beltway (I-495) and to I-270 from the Beltway to Frederick. It would also widen the Baltimore-Washington Parkway by four toll lanes.

The project would be built using a public-private partnership in what Hogan (R) has said would be the largest such deal for highways in North America.

The success of Hogan’s plan hinges, in part, on whether the private companies can figure out what state planners haven’t been able to: how to add four cost-effective toll lanes without having to demolish dozens, and potentially hundreds, of homes and businesses.

“They’re putting a plan on the table, so I think the burden is on them to show how it would be done with the environmental and right-of-way questions we have,” Montgomery County Executive Isiah Leggett (D) said.

Leggett added that he welcomes any attempt to ease gridlock in the region but questions the viability of Hogan’s proposal. “I just think it will be very difficult to accommodate all that,” he said.

The state’s own studies show that it won’t be easy.

A 2004 analysis found that four additional lanes could fit on Maryland’s portion of the Beltway if they were double-decked 80 feet in the air — an idea rejected as prohibitively expensive and impractical.

A 2009 look at the northern part of I-270 determined that adding four toll lanes would require razing up to 250 homes and 10 businesses — a possibility that contributed to Montgomery leaders calling for two less-disruptive, reversible lanes.

A 2012 federal and state study of how to widen the B-W Parkway by two lanes — half the width of Hogan’s proposal — found that doing so would displace up to 14 homes and two businesses while increasing noise and shrinking tree buffers for nearby communities. The study also predicted a “sharp increase” in traffic, noting that a wider road would “carry more traffic, but not necessarily be less congested.”

Doug Mayer, Hogan’s communications director, said the governor isn’t basing his four-lane plan on previous research.

“If the world only moved forward based on studies that are 10 years old, there would be no forward progress ever again,” Mayer said. “ . . . The governor believes in forward-looking, innovative ideas. That’s exactly what this is.”

Maryland Transportation Secretary Pete K. Rahn said the state is keeping the proposal vague to encourage creative design bids. He said he’s confident that the private sector can better minimize impacts. He pointed to Texas, where six new toll lanes were recently added to a Dallas highway without widening it. In areas where land was tight, the private partner submerged the new lanes in a canyon-like trench, with the regular lanes cantilevered over them.

“There are engineering solutions that don’t mean you have to take out a hundred homes,” Rahn said. “I’m hopeful those are the kind of proposals we’re going to receive. If we don’t receive those kinds of proposals, then we’ll have to make tough decisions, but I really believe there are solutions. I know there are ways to deal with very tight rights of way.”

Rahn said the plan includes expanding the American Legion Bridge, a notorious bottleneck, so motorists can remain in toll lanes between Maryland and Northern Virginia, where high-occupancy toll (HOT) lanes opened on the Beltway in 2012. Like Virginia, Maryland’s tolls would fluctuate based on congestion levels to keep traffic moving, but Rahn said the state hasn’t decided whether its lanes would be free for carpools.

Rahn said the public-private partnership would minimize the financial burden to the state — similar to how Virginia added toll lanes to the Beltway, Interstate 95 and part of Interstate 66 in its Washington suburbs.

A team of companies would finance construction and pay the state an upfront fee in exchange for receiving toll revenue long-term. The state’s only expense, Rahn said, would come in hiring “the very best” lawyers and financial consultants to oversee its interests in what are typically highly complex deals. He said the private companies would be on the hook for paying off the construction debt, regardless of how much toll revenue materialized.

“The state will have no risk from the standpoint of how it performs,” Rahn said of the toll lanes.

The $7.6 billion public-private partnership would cover 42 miles on the Beltway and 34 miles on I-270. The bid-solicitation process is in its earliest stages.

The state’s transportation authority would build and manage the 29 miles of toll lanes on the B-W Parkway, assuming that the U.S. Interior Department transfers the road to the state.

“Things have only gotten worse since those [previous] studies were conducted, and we’re finding ourselves choking on traffic,” Rahn said. “Something has to be done. If we’re going to have an impact on this, we’ve got to do something big. It’s the idea that big problems need big solutions.”

But some experts say the logistical challenges remain big, too.

Much of Maryland’s right of way for the Beltway is narrower than in Northern Virginia, where eight homes were torn down to build the I-495 HOT lanes as part of a public-private partnership. The state’s initial design would have displaced more than 300 homes, a project official said.

Neil Pedersen, Maryland’s highway administrator from 2003 to 2011, said the state “never really seriously studied” the double-decker option for four additional Beltway lanes because they would be too costly and noisy.

Because of limited public land along the Beltway, he said, the state focused on how to squeeze in two new carpool lanes, one in each direction.

“We were trying to develop alternatives that would stay within the existing right of way because of the impact that four lanes were expected to have outside of the right of way,” said Pedersen, now executive director of the nonprofit Transportation Research Board. “There are a lot of homes right up next to the Beltway. . . . It’s more of a challenge trying to add two additional lanes in each direction.”

Much of I-270 doesn’t have room without taking homes, he said.

“The existing I-270 is built up right to the edge of the right of way,” Pedersen said. “Therefore, it was assumed it would be very difficult to add any additional lanes.”

The studies were put on hold after the recession hit in the late 2000s, Pedersen said, and local officials didn’t make either widening proposal a high priority.

The Republican governor faces a potentially tough political sell with Democratic-controlled local governments. While the state typically prioritizes megaprojects based on local wish lists, leaders in Prince George’s and Montgomery counties said they first learned of Hogan’s highway plan from the Sept. 21 news conference announcing it. Both counties have typically lobbied the state for transit projects, such as the light-rail Purple Line now under construction, and smaller interchange improvements.

Prince George’s County Executive Rushern L. Baker III (D), who is running for his party’s nomination to challenge Hogan, noted that the governor announced his highway plan “right before the 2018 election.” He said Hogan could face a “backlash” from motorists being asked to pay tolls when they already pay more at the pump from a 2013 state gas tax increase intended to fund transportation projects.

“I’ve just never seen a project that didn’t require state funding in some way, and that money has to come from somewhere,” Baker said. “ . . . The question becomes whether this is a project the governor really pushes through.”

Montgomery Council member Marc Elrich (D-At Large) said he’s concerned local roads won’t be able to handle the additional traffic wider highways would attract. He said he wants Hogan to explain why I-270 needs four new toll lanes when he and other Montgomery officials believe that two lanes that would reverse for the morning and evening rush would do the job with less impact on surrounding communities.

“Is it bold to put two extra lanes on a road that you don’t need?” Elrich asked. “I’d be more impressed if he said, ‘Here’s our analysis. Here’s our data.’ . . . It’s not clear to me that this is very well thought out.”

Meanwhile, Washington Post polls show that local support for paying to escape congestion has grown. A June 2013 Post poll found that 52 percent of residents in Prince George’s and Montgomery supported adjustable tolls on the Beltway, up from 43 percent in 2005.

And some say they’re not sweating the financial or logistical details of Hogan’s plan yet. Bob Buchanan, a developer and president of the 2030 Group for regional business leaders, said he’s just happy that a Maryland governor is talking about the vast majority of people stuck in traffic in a state that has long focused on “transit, transit, transit.”

“I think just getting it on the table and getting people to talk about the viability and the need and how we’ll accomplish it — that’s far more than has been done in a heck of a long time,” Buchanan said. “In the past, it’s been all the reasons why we can’t do something, and yet everyone knows we have some of the worst traffic congestion in the country.”

Emily Guskin contributed to this report.