After receiving hundreds of protests from transit users about the cost and complexity of its original bus-to-subway transfer plan, the Metro board has scheduled additional hearings this month on a new proposal that virtually eliminates the additional cost of such trips for most Virginia riders.

In some instances, commuters would pay less for a combined bus-and-rail trip than an all-bus trip will cost after March 21, when the latest bus fare increase will go into effect. The new increase was approved last Thursday by the Metro board.

Under the first plan proposed last year, but now sidetracked, it would have cost a West Springfield rider $2.90 for a round trip to downtown Washington. It would have cost a McLean resident $2.60.

West Springfield and McLean are both in the same bus zone from downtown Washington. The present round-trip bus fare for either community is $2.10, but that will go up to $2.60 on March 21. The proposed new bus-rail combined fare to the Metro Center station, 12th and G Streets NW, using a new commuter ticket, will be $2.45.

If approved, the new fare structure would go into effect July 1, when Metro is scheduled to open its second rail line, extending from the Stadium-Armory station through downtown Washington to Rosslyn, Arlington Cemetery, the Pentagon, Pentagon City, Crystal City and National Airport stations in Arlington County.

Six public hearings are scheduled. Two of them will be held in Virginia, at 7:30 p.m. March 16 at Swanson Junior High School, 5800 N. Washington Blvd., Arlington, and at 7:30 p.m. March 23 at Lee High School, 6540 Franconia Rd., just west of I-95, Springfield. Virginia residents also may testify at Maryland and District of Columbia hearings, listed at the end of this article.

The proposed new fare structure also would apply to the rail line from downtown Washington to Silver Spring, the first line directly serving Maryland, which is scheduled to open next November.

All proposed Metro fares are stated as round trips, rather than the traditional one-way, because the transit authority plans to offer discounts only for those who travel in both directions.

Also, in this article, the fares cited are those to be charged during rush hours, when the largest surge of passengers - mostly commuters - uses public transit.

However figured, the new transit fare structure will be complicated. It involves a combination of bus fares, charged as a flat rate within the District and on a zone basis in the suburbs, and rail fares, charged everywhere on the basis of distance traveled.

After the bus-rail transfer plan goes into effect, the bus fares would remain the same ones that are now slated to go into effect March 21. However, most Virginia commuters going downtown would pay an intra-Virginia bus fare, saving the 20 cents it costs to go across the Potomac River and, in effect, applying that sum toward the rail fare.

Under the transfer arrangement, Metro planners calculate that commuters transferring from buses to trains at Rosslyn for trips downtown would save six to 13 minutes in reaching downtown. Those transferring from Shirely Highway corridor buses at the Pentagon would get to the Farragut Square station in about the same time as at present.

But those transferring at the Pentagon destined for Southwest Washington and the Federal Triangle would be delayed, in a typical case, about 10 minutes. For this reason, Metro plans to continue running many bus routes across the 14th Street bridge to the Southwest-Triangle areas.

For the most part, however, the Virginia buses would be terminated at Rosslyn and the Pentagon and, to a lesser extent (for Alexandria passengers), at National Airport.

To overcome inequities in fare collections, such as the one between West Springfield and McLean commuters, or between South Arlington and North Arlington riders, Metro is proposing to make the rail fare identical for trip downtown from either the Pentagon or Rosslyn stations.

In future years, after a second Potomac River rail crossing is completed parallel to the 14th Street bridge, a fare differential will be instituted.

The forthcoming hearings will deal only with the Metrobus and metrorail fare system, and not with the changes in the bus routes. The route changes are currently in the process of being approved by the Metro board following the earlier set of hearings just October and November.

A total of 157 witnesses presented testimony, much of it critical of the proposals, at those hearings. Since then 96 letters and several petitions bearing 747 names were submitted.

Following is a summary of the fare proposals which will be considered at this month's hearings. METRORAIL FARES

Rush Hours (6 to 9:30 a.m., 3 to 6:30 p.m. weekdays) - 50 cents to get aboard a train and ride for three "composite miles," with 10 cents for each additional composite mile. Composite miles are calculated by averaging the straight geographic distance and the actual travel distance between stations. If two stations are geographic distance and the actual travel distance between stations. If two stations are geographically six miles apart but a train must travel 10 miles between them over a roundabout route, the fare is charged for eight miles.

All Other Hours - 40 cents to get aboard and travel two composite miles, with 10 cents for each additional mile. The effect is to encourage short rides outside rush hour. From Dupont Circle to Judiciary square, for example, the offpeak fare would be 40 cents, the sams as on a bus. METROBUS FARES

These fares would be those that were approved last Thursday, to go into effect March 21. During rush hours in Virginia, this would be a range from 70 cents to $1.50 to get all the way by bus to downtown Washington, or from 50 cents to $1.30 to get to Rosslyn or Pentagon subway stations. Free transfers would be provided between buses but not between buses and trains. BUS-RAIL FARES

Occasional Trips - Full bus fare plus full train fare, paid separately. This would be substantially higher than present bus fares in many instances, but lower in others. For examples, a one-way trip from Falls Church to downtown Washington that would cost $1.10 by bus and train.In off-peak hours, the trip would cost 70 cents by bus and 65 cents by bus and train.

Round Trip in One Day - This provides a discount of 40 cents or 50 cents for a round trip, depending upon the time of day.

A passenger boarding a bus pays the full fare, gets a special transfer and saves it. Arriving at the subway station, the passenger pays the full train fare downtown.

Returning, the passenger pays the full train fare and, arriving at the end of the train ride, validates the transfer that was obtained on the inbound trip. This is done with an automatic stamping device in the station concourse. The transfer will be accepted as a full bus fare to any destination in the District.

Several additional steps are needed for travel that involves more than one change of vehicle, such as bus-rail-bus.

This method was proposed last fall by Metro for all bus-rail commuters, but was criticized by many people as being too complicated. It "may appear to be complicated," Metro's planning office argued back in a recent report to the board, "but once the public has actually experienced the transfer procedure . . . they will find it no more difficult than the transfer procedure in effect today."

Commuter Pass - Metro plans to sell a two-week ticket. The card will have a pre-determined amount of rail fare value encoded onto magnetic tape on one side. The cost of each trip will be subtracted from this value by electronic devices installed in turnstile-like fare gates in each station concourse. On the other side, the card will be identified as a bus pass, good for unlimited free travel throughout the District and for a 50-cent basic bus fare in the suburbs, with additional zone fares to be paid in cash. The price of the ticket will be set at a level that, in effect, will give each rush-hour commuter a 75-cent daily discount from full fare for each round trip.

Here, according to Metro, are some sample round trip fares from Virginia points to downtown Washington:

From anywhere in Arlington outside the G (for government) zone, transferring at either Pentagon or Rosslyn stations - All bus, $1.80; bus-rail combination, using transfer validation system, $1.90; proposed bus-rail pass, $1.65.

From Old Town Alexandria, transferring at National Airport - All bus, $1.80; bus-rail combination, transfer validation, $2.20; proposed bus-rail pass, $1.95.

From Falls Church or Annandale, transferring at either Pentagon or Rosslyn - all bus, $2.20; bus-rail combination, transfer validation, $2.30; proposed bus-rail pass, $2.05.

From West Springfield or McLean, transferring at either Pentagon or Rosslyn - All bus, $2.20; bus-rail combination, transfer validation, $2.70, proposed bus-rail pass, $2.45. ELDERLY AND HANDICAPPED

Half fare (rounded downward to the closest nickel) for persons 65 or older and medically certified handicapped, at all hours. HEARINGS

All hearings will begin at 7:30 p.m. Witnesses may get on the list to testify at any hearing by telephoning 637-1092. Additional information is available by telephoning 637-1328. Metro lists the hearings as Docket B77-1.

March 14, Maryland-National Capital Park and Planning Commission, 8720 Georgia Ave., Silver Spring.

March 15, Lincoln Junior High School, 16th and Irving Streets NW, Washington.

March 16, Swanson Junior School, 5800 N. Washington Blvd., Arlington.

March 21, Ballou High School, 4th and Trenton Streets SE., Washington.

March 22, Kemmoor Junior High School, 2500 Kenmoor Dr., Landover, Prince George's County.

March 23, Lee High School, 6540 Franconia Rd., Springfield, Fairfax County.