District of Columbia City Council Chairman Sterling Tucker asked yesterday for a study of bus fare rollbacks and resumption of some express bus service for city residents adversely affected by the new Metro plan that uses buses to feed the subway.

In a letter to Metro general manager Theodore Lutz yesterday. Tucker noted that the new combined bus-rail fare structure puts a heavy financial burden on residents of Southeast and Far Northeast D.C. He asked Metro to consider a possible rollback in the bus fare - which is 50 cents during rush hour - and a return to morning service of some express buses that have been replaced by the train.

Under the new fare structure, which took effect July 1, riders must pay two fares if they transfer from train to bus. That has meant a 40-to-50-cent increase in round-trip fares for some city residents. Most suburban residents incurred no more than a 10-cent increase.

The Metro board, of which Tucker is a member, has scheduled some fare actions for its meeting today.

In another Metro matter, Maryland Transportation Secretary Hermann K. Intemann met yesterday with Charles Bingman, deputy administrator of the federal Urban Mass Transportation Administration (UMTA), which approves federal grants for subway construction.

Intemann is trying to decide whether to sign a contract that would release $328 million in U.S. funds for subway construction, primarily on the line from Tenley Circle NW to Shady Grove in Montgomery County.

Intemann asked that the Montgomery County Council and executive endorse his signature by assuring that they would take all action needed to complete the Shady Grove Line. The Council did so, but County Executive James P. Gleason refused because, he said, he has no federal guarantee that another subway line, from Silver Spring to Glenmont, will be completed.

That line is under an engineering analysis for possible cost reduction. Gleason has agreed to the analysis but wants an up-front commitment that it will be built no matter what it costs.

Federal officials have refused to give that commitment although they repeatedly have indicated that they favor the line.Several Department of Transportation officials feel that a cost savings of as much as 30 per cent is possible with revised construction methods and alignment.

Intemann said in an interview that "I left the meeting with a feeling that if we can cooperate together we can find a way to resolve this." He said he would meet with Gleason before deciding whether to sign the contract.

Metro officials say that the contract must be signed by Aug. 15, or that some construction projects, including one in Virginia, will have to rebid. Intemann said that "I think if we went to those contractors and asked for an extension, we could get it."

Metro's subways, plagued with mechanical problems since the Blue Line from National Airport to RFK Stadium opened July 1, had their best evening rush hour in weeks yesterday with no delays, officials said. The morning was a different story, when two trains broke down and disrupted the rush hour.