Advocates said Tuesday that Maryland’s transportation chief has agreed to make a monorail on Interstate 270 part of a traffic relief study examining the potential environmental impacts of adding toll lanes to the highway.

Charlie Maier said Maryland Transportation Secretary Pete K. Rahn told him and other monorail advocates at a meeting Tuesday that their idea of building a 27-mile monorail between Frederick and the Shady Grove Metro station is “worth additional exploration.” Rahn said it “makes sense” to include monorail as an option in an upcoming study of adding toll lanes to I-270 north of Interstate 370 in Gaithersburg, according to Maier.

“The discussion about the prospects for monorail in the 270 corridor went very well, very positively — and that’s exciting,” Maier said of the meeting with Rahn. “We do appreciate Secretary Rahn’s interest, attention and initiative to include monorail in the environmental study process.”

Rahn declined to say whether he had given the monorail advocates a thumbs up. When asked about his reported comments at the meeting, Rahn spokeswoman Erin Henson responded in an email with this statement attributed to the secretary: “It was a good meeting, and we look forward to continued discussions.”

Robert Eisinger, a Montgomery County developer, is promoting the idea of an elevated monorail adjacent to I-270 amid debate over Maryland Gov. Larry Hogan’s proposal to add toll lanes to I-270 and the Capital Beltway. Eisinger has touted a monorail as a fast, reliable and cost-effective way to relieve traffic congestion by taking thousands of motorists off the highway.

According to Eisinger, a privately funded consultant’s study estimated that the line could be built for $3.4 billion within the highway’s right of way, so no homes or private property would be affected.

Eisinger’s idea has attracted interest among some Montgomery officials, particularly those who have said the Republican governor’s plan to relieve traffic by adding toll lanes needs to include more transit options.

Under Eisinger’s proposal, the trip between Frederick and Shady Grove would take 31 minutes, with trains stopping at six stations. He said that he does not have a plan for how to pay for the project but that it probably would entail a public-private partnership.

Rahn will seek approval Wednesday from the state’s Board of Public Works to begin pursuing teams of companies for a public-private partnership for the toll lanes project. Rahn has said companies would build the lanes, pay for their construction and operate them in exchange for keeping most of the toll revenue over 50 years.