A Metro board committee, seeking to close out a years-old preoccupation with subway construction among Metro's senior managers, recommended yesterday that reliability of bus and rail service be adopted as the transit system's "paramount" goal.

The panel proposed that the board set specific goals in such areas as frequency of breakdowns, on-time performance and absenteeism. Metro staff members already monitor those figures closely but to date the board has never ruled on precisely what levels are acceptable.

Like many U.S. transit systems, Metro is suffering from stagnating ridership and rising operating deficits blamed largely on public perceptions that service is unreliable.

"We must turn the corner from construction to operations," said Metro board chairman the Rev. Jerry Moore.

The committee proposals, which will be considered at a future meeting, reflect a belief that Metro, having fought to obtain some $4 billion in subway stations, buses and other equipment, now is giving too little attention to running service on time.

Noting that in Montgomery County more than 30 percent of the Metrobuses run behind schedule, the committee called for tighter on-time performance. Ninety percent on time would be acceptable, it said.

Metro officials currently predict that because of maintenance problems, the rail system will operate with less than its full rush-hour complement of 256 cars on 25 percent of the days next fiscal year. The committee recommended making 20 percent the goal.

The committee called for a crackdown on employe absenteeism, which has increased in recent years. It also recommended devoting up to $75,000 to a financial incentive program for senior operations officials.

In other developments yesterday:

* The board endorsed a design for a monument honoring Union Civil War dead to be built next to the Rhode Island Avenue rail station. Designed by Howard University architecture student Tyrie Bivings, a granite slab and park grounds will mark the site of the old Harmony Cemetery, where the remains of thousands of soldiers rested until they were moved in the 1960s to make way for development.

* The board affirmed plans to conduct new hearings on the southern Green Line alignment next week. Hearings will be convene at 7:30 p.m. at Birney Elementary School in the District on June 15 and at G. Gardner Shugart Junior High School in Prince George's County at 7:30 p.m. on June 16.