The Metro board, overriding objections from its technical staff, voted yesterday to continue running certain Connecticut Avenue buses to and from downtown after the Red Line extension opens through to Van Ness next month.

A staff analysis presented to members before the vote said the adopted plan will wipe out close to $900,000 in savings on local government subsidy bills that would have been possible under original plans to terminate most Connecticut Avenue buses at Van Ness and eliminate other lines altogether.

The plan approved yesterday without opposition will create parallel bus and rail service, which the board says it opposes in principle.

But Maryland board member Cleatus Barnett said proposals to make bus passengers transfer to rail at Van Ness would be a "bad deal" for commuters from Montgomery County. The Rev. Jerry Moore of the District, which cosponsored the plan adopted yesterday, said the original proposals would hit too heavily at bus-dependent senior citizens and handicapped people living along the Connecticut Avenue corridor.

In one form or another, yesterday's debate is replayed each time a new segment of subway opens. Metro's theoretical goal is to maximize use of the rail system, built at enormous cost and intended to reduce traffic congestion. But local communities often raise intense political opposition to plans to cut bus service, charging that local needs are ignored in the process.

Yesterday's vote calls for some of the "L" lines to retain their current routing downtown, some to be curtailed and some to be eliminated. Between Dec. 6, when the new subway line opens, and Jan. 31, when the new bus schedules are to take effect, bus routes will remain as they are now.

The new bus routes as of Jan. 31 are as follows:

* The L-3 (Wheaton-Federal Triangle) and L-9 (Aspen Hill-Federal Triangle) will continue to operate their present routes, though passengers will pay a surcharge, tentatively fixed around 50 cents. Previous plans called for these buses, which account for about 1,700 rides per weekday, to terminate at Van Ness.

* The L-5, which now connects Chevy Chase Circle and the Foggy Bottom area, will also stay on its current route, though also with a surcharge. Earlier plans called for it to be eliminated.

* The L-2 (Van Ness and Connecticut-Federal Triangle) will be realigned to serve upper Connecticut Avenue, linking Chevy Chase Circle and McPherson Square.

* The L-4s, now linking Chevy Chase Circle and Wheaton to Federal Triangle, will terminate at Dupont Circle. The Wheaton bus will be redesignated L-6.

* The L-8 (Aspen Hill-Federal Triangle) will also go no farther than Dupont Circle.

* The L-1 and the L-7, both express routes linking Chevy Chase Circle and points downtown, will be eliminated.

Metro staff members argue that parallel service wastes money at a time when Metro faces serious financial difficulty. If rail cars have empty seats, they say, it makes sense to channel riders into the subway, rather than paying for a driver and fuel for the same trip on the surface and tying up a bus that could be used elsewhere.

Metro operations chief Theodore Weigle told the board yesterday that if it approved parallel service "we've got to be prepared to pay for it . . . The added cost is going to come from more payments from the jurisdictions."

But Maryland's Barnett said that Van Ness transfers would "unduly penalize long-distance bus riders both in terms of time and cost." Many commuters have complained that the transfer at Van Ness would raise fares while adding time to their trips.

The District, meanwhile, opposed the old proposal on the grounds it would create hardships for Connecticut Avenue residents who rely on buses for short-haul trips. People testifying at public hearings "wanted a through bus service to get them up to the Safeway at Chevy Chase Circle," said D.C. board member Tom Downs.

Commuters from the Chevy Chase area in the District would also have had less bus service available to them.

Staff members, however, say that quirks in Metro's system of billing local jurisdictions for bus and rail subsidies allow individual jurisdictions in some cases to benefit financially at others' expense by keeping their own people on buses and out of subways.

For instance, the approved plan, which will allow Montgomery County riders to remain on buses, could result in more profitable operation of those buses and will lower the county's share of total rail subsidies, because fewer of its people will be riding the subways.

In other business yesterday, the board:

* Made permanent an experimental program under which rail riders can bring bicycles aboard trains. Participants are required to obtain identification cards and undergo a safety course with Metro. So far 630 have applied for the permits.

* Agreed to a request from Montgomery County to continue current transfer arrangements when the county's "Ride-On" bus service raises its fares from 45 cents to 50 cents next month and begins charging 10 cents for transfers. Metrobus drivers accept Ride-On transfers as worth 45 cents toward the full Metrobus fare. Ride-On accepts Metrobus fares as worth full fare.