The agency that is in charge of planning and parkland in the Washington, D.C., suburbs rejected a key Maryland State Highway Administration document on Thursday, setting up a possible showdown between local planners and the state over the Hogan administration’s plan to widen Interstate 270 and the Capital Beltway.

By a vote of 9-1, the bi-county Montgomery National Capital Park and Planning Commission (MNCPPC) rejected the state’s alternatives retained for detailed study, or ARDS, detailed proposals by SHA to make Gov. Lawrence J. Hogan Jr.’s road-widening plan a reality.

In rejecting the seven surviving designs, commission members concluded that the Maryland Department of Transportation didn’t offer a wide enough array of options — or provide enough supporting information — for the MNCPPC to sign on.

“Their environmental impact statement has to be complete and comprehensive, and that’s what we’re trying to get them to do,” said Carol Rubin, senior project manager with the Montgomery County Planning Department.

“We are the stewards of the natural environment in Montgomery and Prince George’s County. So you want to know what you’re getting into. That’s why it’s so important to have a complete set of alternatives to actually study,” she said.

In a statement Thursday evening, MDOT responded to the ARDS vote.

“The Maryland-National Capital Park and Planning Commission is one of multiple stakeholder agencies involved in the [National Environmental Policy Act approval] process. No one agency has veto powers,” Erin Henson, MDOT spokeswoman, wrote. “We will continue to work collaboratively with them every step of way. It’s important to note that the concurrence of ARDS is related to the NEPA process. Several of MNCPPC’s questions are related to the [public-private partnership] solicitation process that is governed by the Board of Public Works, not the stakeholder agencies.”

Because of the planning commission’s status as a “cooperating agency” on the state’s planned road widening project, Thursday’s vote sets up a possible showdown with the SHA before the Federal Highway Administration, a mediated session at which both sides present their arguments.

“That doesn’t mean that they’re going to address our concerns, [but] it gets us a seat at the table to push forward our ideas,” Rubin said.

Critics of the state’s plans said the commission’s vote offered more evidence that the administration’s approach is weighted too much toward cars and not enough toward transit and traffic mitigation.

“What MDOT has put together is having a hard time standing up to scrutiny,” said Brad German, co-chairman of the Committee Against Beltway Expansion, in a news release.

The commission’s vote followed by one day a victory, at the Board of Public Works, for the governor’s plan to have private firms finance, construct and maintain new lanes on the Beltway and I-270.

Even as the dust settled from the panel’s contentious — and for some, confusing — vote, many local officials and other close observers were still trying to figure out what it all meant.

Marilyn Balcombe, president of the Gaithersburg-Germantown Chamber of Commerce, said she is “thrilled” that Hogan amended his original plan to put the widening of I-270 ahead of the Beltway.

“Never in my wildest dreams would I have thought that that was going to be the outcome,” she said.

But like others, she said a measure of uncertainty lingered, particularly given the governor’s insistence that the widening of the American Legion Bridge shift to Phase 2, along with the addition of new lanes to the stretch of Beltway that runs through Montgomery County.

“It doesn’t make sense to [widen I-270] without the bridge,” she said. “We’re thrilled that I-270 is going forward, but it really is confusing as to what that means.”

Now that the phases have been flipped by the BPW’s vote, Henson wrote, “Based on the direction of the Board of Public Works, we are going to spend the next few months repackaging the solicitation for Request for Qualifications for the new phase of I-270. We also will need to begin engaging the industry with all the details of the I-270 phase. That work began immediately following the Board of Public Work’s approval of the designation of the I-495 & I-270 P3 Program as a public-private partnership.”

John Townsend II, head of government relations for AAA Mid-Atlantic, believes Hogan outsmarted the Montgomery County officials who urged him to prioritize I-270 over the Beltway.

He predicts massive nighttime backups on the I-495’s Inner Loop as Maryland motorists attempt to leave job sites in Virginia to go home.

“That’s a doomsday scenario for us,” he said. “I think it has to go back into Phase 1.”

“When [Virginia’s] express lanes are extended to the American Legion Bridge, and they dump all that traffic onto Maryland, it becomes untenable,” Townsend added. “It becomes the biggest chokepoint on the East Coast, and perhaps in the whole nation.”

Montgomery County “will rue the day that they let that go to Phase 2,” he concluded.

Several Montgomery County officials said Hogan’s willingness to alter his plan was a sign that a more cooperative relationship might be around the corner.

“For two years, there’s been a my-way-or-the-highway approach,” Del. Marc Korman (D-Montgomery County) said. “Yesterday involved some compromises, finally. So hopefully that opens things up to some more actual discussion.”

Others had a decidedly different view of the changes the Board of Public Works appeared to adopt on the fly. They noted that state Treasurer Nancy K. Kopp asked for details of the amendments after the vote occurred.

“This is not the caliber of decision-making Maryland deserves,” said Gary V. Hodge, a former Charles County commissioner and transit advocate.

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