Montgomery County transportation officials, at the request of a County Council committee, are exploring the feasibility of the county taking over a Metrobus route through downtown Bethesda.

The council's transportation committee has asked to see figures on the cost of replacing the C-1 Metrobus, running from Glen Echo to Friendship Heights via Wilson Lane, with the county-run Ride-On buses. "This was suggested by the committee that we look into it," said Genevieve L. Leary of the county's transportation department. "We'll give some figures to the committee."

The committee, chaired by council member Neal Potter, plans to review those findings at its meeting in Rockville Thursday. The full seven-member council would have to review any changes proposed by that three-member committee.

Metro had considered the route "marginal" because of low ridership, according to Potter, but has not taken action yet to discontinue the route. A subway station is to open there next year. Potter said the county would like to take over the state subsidy for the C-1 line that currently goes to Metro.

The county has of late been expanding its Ride-On system, particularly as the cost of maintaining Metrobuses continues to climb. The two systems work side-by-side in Silver Spring, and County Executive Charles W. Gilchrist, in his proposed 1984 budget, has asked for more money to add three Ride-On bus routes to Bethesda.

Those three routes, scheduled to begin next May, would be new routes not now serviced by Metro.

Should the council decide to replace the C-1 route with a new Ride-On route, that takeover would be in addition to that expansion already planned for Ride-On in Bethesda.

Also, Leary said, the county has been working on a plan, jointly with Metro, to begin restructuring the entire bus system in the county, once the Metrorail Red Line opens to Shady Grove Road several years from now. Ultimately, with Ride-On expanding and with the subway providing the fastest transportation to downtown Washington, Metrobus routes could be restricted to the main north-south routes, such as Wisconsin Avenue and River Road, Leary said.

She added that there were no plans to completely phase out Metrobus in Montgomery.