Montgomery County is forsaking federal aid and spending $12 million of its own money for 155 new buses to expand its neighborhood Ride-On system and retain the option of replalcing Metrobus service in the county. Ride-On is not small potatoes; it carries 20,000 passengers a day.

Fairfax County is studying how to replace Metrobus service east of Shirley Highway and south of the Capital Beltway with county-owned or chartered buses.

Prince george's County is talking to private bus companies to see if they would like to replace Metrobus on some routes, perhaps with a county subsidy.

These events have been spurred by the costly contract Metro has with its 5,000 unionized transit workers and may spell the beginnings of a major change in transit here. Instead of one Metro system to serve D.C. and the Maryland and Virginia suburbs, there could well be Metro's subway and five or six different bus systems, each marhing to a different local drum.

Fares, schedules, availability of information and the quantity and quality of buse service differ confusingly from section to section of Metro's service area today. One only can imagine it getting worse with many little systems, doing different things at different times, charging different fare, but each ultimately centered on a subway station.

As local governments consider their alternatives, the questions they face are these:

The price of leaving Metro would be to do without federal aid for the purchase of buses, building of garages and salaries to drivers. Would enough be saved in labor costs over the long term to offset that price?

Would the escape from the types of costs and problems Metro faces be real, given the probability that labor will organize county-owned bus operations?

This is half the story. On another front, state Sens. Adelard Brault (D-Fairfax) and Thomas Patrick O'Reilly (D-Lanham) are pushing bills in the Virginia and Maryland legislatures that would amend the law requiring Metro and its unions to settle disputes through binding arbitration. rIn the opinion of Metro management and local government analysts, the provision gives the union a great advantage.

It was vigorously sought by the Amalgamated Transit Union in 1972, when Congress was writing legislation to permit Metro's takeover of four privately owned area bus companies. The purpose was to guarantee the absence of transit strikes in the nation's capital.

It has not done that. There have ben several wildcat strikes, including one that tied up the city for eight days during a heat wave in 1978. But the provision has deprived Metro of the classic management right to insist it will pay no more than a certain figure. Exercise of that right, of course, would imply willingness to accept a strike.

Walter Bierwagen is internatioinal vice president of the Amalgamated Transit Union, a former leader of Local 689, which represents most of Metro's transit workers, and a skillful Capitol Hill lobbyist. "The greatest things we have achieved have been in negotation or in arbitration," he said. "I can't think of anything significant we have won out of a strike situation."

A change in the binding arbitration requirement would have to be adopted by the Maryland and Virginia legislatures, the D.C. City Council and Congress. Only in Virginia would passage of something perceived as antilabor be automatic.

But this is the year of Ronald Reagan and of the new conservative Congress, the year of mounting budget problems in the District of Columbia, which pays dearly for Metro service, and the year of heavy cutbacks in the rural Maryland highway program because of heavy transit demands on the state transporation fund from both the Baltimore and Washington areas.

Metro General Manager Richard S. Page has decided to push for the change, but it is not certain he will be backed by the Metro board, some of whose members talk rough in public but become panicky at the prospect of a transit strike.

"Lots of people say this is not the practical thing to do," Page sad. "I didn't think it was either, but times have changed. I'm not anti-union; I am anti-compulsory arbitration . . . . I believe in collective bargaining, because in collective bargaining one of the primary issues that must be considered is the employer's ability to pay . . . . It was not considered in this [most recent] arbitration, and I 'Don't think compulsory arbitration permits it to be considered. . . "

As a result of the arbitration awarede in January, Metro's bus drivers and subway train operators make $22,000 a year before overtime. While inflation continues, their raises come without regard to local governments budgets. They automatically get a raise four times a year, and it matches the rate of inflation for the first 9 percentage points, then matches approximately two-thirds of each additional point.

Local and state governments are paying more than $110 million in subsidies for Metro this year and are being asked to pay about $160 million next year. Almost two-thirds of that subsidy is for bus service. The salary protections for metro's employes exceed those for schoolteachers, policemen and firemen and thus raise difficult fairness issues for local governments.

While some of the talk about leaving Metro is political saber rattling, much of it is real. Montgomery County's Ride-On has demonstrated the success of a locally controlled and operated bus system that concentrates on neighborhood service and feeds and regional subway system. Ride-On's ridership has shown a 10 percent increase in the past year.

In 1980 it cost Montgomery County $20.50 per hour (without subtracting fares) to operate Ride-On and $37 per hour to operate Metrobuses on Montgomery County routes. Ride-On costs 80 cents per passenger per trip to operate; the passengers paid an average of 28 cents. Metro cost 95 cents per passenger per trip; passengers paid an average fare of 51 cents.

The salaries for Ride-On drivers start at $12,900 per year and reach a maximum of $17,443. Ride-On can use as many part-timers and substitutes as it wants. These are categories unions traditionally oppose.

Metrobus drivers start at $16,827 and in 30 months are eligible for the maximum, before overtime, of $22,432. With bonuses for night work, snow days, overtime, charters and the other goodies, many take home $25,000. Last year, 142 drivers made $28,000 or more and two drivers made more than $40,000.

Total part-timers at Metro cannot exceed 10 percent of the full-time force, and there is no such thing as a substitute; Metro must employ enough drivers at full-time salaries to run the schedule even if there are several absences.

Thus, savings are possible in labor. What about other costs?

By buying its own buses, Montgomery County is foregoing $9.6 million in federal aid. On the other hand, county taxpayers avoid two federal strings: They do not have to guarantee that the buses will not take jobs away from unionized employes (Metro drivers) and they do not have to equip every other business with a wheelchair lift.

"I regard Ride-On as a positive, constructive adjunct to Metro," said Montgomery County Executive Charles Gilchrist, before dropping the other shoe. "Inevitably, as the costs of Metro increase, I think Ride-On does become significant as a potential alternative to a greater or lesser degree."

In addition to the loss of federal aid, there is another reason the long-term savings of Ride-On might not be as real as the short-term ones. Both the Amalgamated Transit Union and the American Federation of State, County and Municipal Employees are attempting to unionize Ride-On drivers.

Despite right-to-work laws, bans on collective bargaining and other devices that governments, particularly in Virginia, devise to keep public employes in line, aggressive unions have found ways to recruit and bargain. Local governments will have to ask themselves if there is really a gain if they leave Metro and wind up with a more vigorous, more militant labor union (AFSCME) than the one they have now (ATU).

John F. Herrity, chairman of Fairfax County's board of supervisors, said his biggest problems with Metrobus are work rules such as those that limit part-timers and forbid substitutes. He hopes to avoid them in the country's plan to avoid them in the country's plan to replace Metrobus south of the Beltway and east of Shirley Highway, the area that will feed the future Huntington subway station.

Prince George's County Executive Lawrence J. Hogan gets at the gut issue for many politicians. "Within a few years, a Metrobus driver is going to make $42,000," Hogan said. "That's absurd. The public is not going to stand for it."

Talk by suburban governments about leaving Metrobus has traditionally bothered District of Columbia politicians. Sterling Tucker, former chairman of the D.C. City Council, put it best. "We would have what's left," he said.

Metro has been stuck with the cost-of-living protection clause guarded by binding arbitration since it began running the buses 1973. It happened like this:

In December 1972, with service deteriorating rapidly, Congress approved a $70.8 million grant for Metro to take over four area bus systems, but required Metro to honor existing labor contracts and to use binding arbitration.

The contract was expiring between the drivers and mechanics at the D.C. Transit System, the biggest of the four companies, and a strike appeared imminent. Congress permitted Metro to observe the negotiations but not to participate. The union pursued full cost-of-living protection as its first priority, and the company resisted for a while. But with no financial stake other than to remain whole until the takeover, D.C. Transit agreed to Local 689's demand for the clause.

Metro labor relations specialist Peter Sheehan was the official observer, and he sat by helplessly, although he protested the union's cost-of-living proposal.

"I have felt like a castrated bull in a cow barn," Sheehan's notes say he said after the settlement was reached. "I would like to have done something, but haven't got the equipment. Considering the situation [Metro] finds itself in, it seems fair to say that you have resolved the differences between you in a fair and equitable manner . . ."

Senior staff member at Metro, including General Manager Jackson Graham, considered rejecting the contract because of the clause, but the debate never reached the board in public session. The pressures to accept the contract were too great. The money for the takeover, complete with federal strings, was in the bank. Transit service in the Washington area was disintegrating, and the first small subway line was still at least three years away.

There was another factor. "Cost-of-living wasn't as big a deal at that time," Graham said in recent interview. "We were talking only about 5 or 6 percent annual inflation." In a recent quarterly adjustment, Metro had to pay its drivers the equivalent of an 18-percent increase.

Metro has tried to modify or eliminate that cost-of-living clause in every subsequent contract, and the issue always has gone to arbitration. The recent contract guarantees full quarterly cost-of-living protection for the first 9 percentage points of inflation before there is any reduction in full percentage protection. That contract contains the first modification of the cost-of-living clause since the takeover.