Maryland Gov. Larry Hogan (R) has postponed funding a busway in the heavily congested Interstate 270 corridor for at least six years, significantly delaying a transit project that Montgomery County is relying on to develop the upcounty without making traffic worse.

Hogan’s proposed six-year transportation budget includes no money for the Corridor Cities Transitway, which has been planned since at least 2000 to connect the Shady Grove Metro station at the end of the Red Line with the upcounty. The first nine-mile segment would run between Shady Grove and the Metropolitan Branch MARC commuter rail station in Gaithersburg. Delaying the project would save the state about $78 million over the next six years, according to the budget.

I-270, which runs parallel to the Red Line, links upper Montgomery, Frederick County and points beyond with the Capital Beltway. The highway has almost daily traffic jams during rush hours and has grown more congested as Washington-area workers seek more affordable housing in fast-growing outer ­suburbs.

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Montgomery officials say the I-270 corridor is critical to the county’s continued economic development as a hub for biotechnology companies. Much of the growth planned for west Gaithersburg can’t proceed without the transitway’s construction being funded. Moreover, county economic development officials say it’s difficult to attract companies to the area without transit-friendly office sites.

Erin Henson, spokeswoman for the Maryland Department of Transportation, said the state had to delay some projects because revenue from the state gas tax recently came in $746 million below projections, which had been based on higher gas prices. She said the state reexamines that revenue twice a year.

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“If gas prices go back up and the revenues change, we can reevaluate the budget and it could be added back,” Henson said.

She noted that the state is soliciting bids for $100 million worth of congestion-relief work on I-270. Maryland officials have said they’re asking the private sector for high-tech ways to make traffic flow faster.

“We want quick relief,” Henson said.

The news of the transitway’s delay caught Montgomery officials and transit advocates by surprise because previous six-year budgets had included money to complete the line’s design and purchase right of way. Two advocates said that the latest state timeline they had seen had construction beginning in 2019 and the transitway carrying passengers in 2022.

Although the line is now at 30 percent design — meaning its route has been chosen and major elements of it decided — the funding delay would mean the project’s final design and right-of-way acquisition wouldn’t proceed until at least 2023.

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“It’s just very disappointing,” said Marilyn Balcombe, president of the Gaithersburg Germantown Chamber of Commerce. “We’re at a very critical stage, so it doesn’t make fiscal sense to stop this project right this minute.”

Balcombe said reviving the project six years from now probably would require redoing much of the planning and engineering work necessary to apply for federal construction aid.

“To take a project to 30 percent completion and then put it on a shelf for six years makes no sense at all,” she said.

Richard Parsons, vice chairman of the Suburban Maryland Transportation Alliance, said he thinks the governor delayed the project because of a lack of funding. However, Parsons said, the state could get the money by having express toll lanes on the highway — an idea that the Hogan administration has said would be too expensive and take too long to provide relief.

“We can do it if they look at tolling on I-270,” Parsons said. “That’s a big revenue source. There are over 210,000 people a day stuck in that nightmare, and it’s fixable.”