A top-to-bottom reorganization of the Metro transit authority's staff that puts bus and rail operations under separate operating officials of equal rank was approved yesterday by the Metro board.

The new setup, effective May 1, abolishes the former office of deputy general manager and creates four new slots to be filled by four assistant general managers.

They will deal with major areas: finance, design and construction, transit sercices and internal administration.

While the shuffle is of little apparent concern outside Metro headquarters at 600 5th st. NW., Metro general manager Theodore C. Lutz said it is intended to produced better public service and more effective staff direction.

The general outline of the reorganization was announced in December when Warren D. Quenstedt requested retirement after nearly 10 years as deputy general manager. The post was left vacant.

Metro's present organization was created when the transit authority was solely a subway-building agency. Lutz said the new organization reflects the fact that Metro now is a major operators of both buses and trains.

Under the old organization, almost every department chief was responsible directly to the general manager. Except for some specialized officials - such as those dealing with Congress, labor relations, minorities and the public - the departments will be responsible to one of the new assistant general managers.

From a public stanpoint, the most visible change will be the creation of two offices to run bus services and rail services, which will be under an assistant general manager.

The lack of such control - and clear line of responsibility - was widely blamed for the breakdown of bus service after the Bicentennial fireworks display here last July 4. Thousands of would-be passengers were stranded on street corners for lack of buses and arrangements to give buses priority over automobile traffic.

None of the people to be put into the newly shuffled or created jobs has been officially selected, Lutz said.

In taking yesterday's action, the Metro board also removed a ceiling that has kept top salaries of department heads at $38,934 for several years. The new Salaries will range from that figure up to $47,767.

In another Metro development, the Falls Church City Council gave final approval Wednesday night to the signing of an interim financing agreement intended to guarantee that at least 60 miles of the Metrorail system will be built. It was the last of the area's local governments to act.