ONCE AGAIN, Secretary of Transportation Brock Adams had issued a statement on the future of Greater Washington's Metrorial system - and once again, there is enough obfuscation and qualification in his pronouncements to leave regional officials wondering whether the system is on the verge of a terrible collapse or a genuine breakthrough. If anything is clear in the Adams statement of last week, it is that he is contending that there won't be enough federal money available to finance the full 100-mile system that regional governments had agreed to. Therein lies a complex dilemma, for any cut of a major subway line could produce intraregional warfare.

The 100-mile system was laid out and approved a good eight years ago, and any cut would deprive one or more local jurisdictions of some service. Yet all the area governments have contributed money - and that money went to build city and inner-suburban segments first. Thus, as staff writer Douglas B. Feaver noted in a report on the Metro deliberations, with all the money gone and the system not completed, there looms the boggling prospect of trying to work out who would reimburse whom - and with what. No wonder, then, that Mr. Adams, regional leaders and Metro officials are all watching the progress of a federally ordered "alternatives analysis" of transportation-system options.

The task force making this study now reports that it has reduced the number of options from 1,764 (that's what it said) to 72. At any rate, hopes are to whittle this down to three system options by January, and for the local and federal leaders to agree on one sometime shortly afterward. In the meantime, they are supposed to produce a financial plan for building and operating a system. Mr. Adams says he wants that plan "immediately," and in any case must have it before he will approve financing for any more subway.

It all sounds sort of logical, but there's a chicken-and-egg factor: Mr. Adams is saying no more money until the locals agree on proposed costs of building and running a system - while locals argue that they cannot answer that question until they know how much they are going to build. Thus without a strong dose of good faith between now and the next task force report, the entire regional financing of the Metrorail system could come unstuck.

We share some of the concern voiced by regional officials about what they see as a growing number of federal requirements to answer questions that may already have been answered. Each additional study, each new federal construction requirement involves more time and money - but does not result in more tracks and cars. Still, there must be more local attention addressed to how operating costs will be financed. And though Mr. Adams apparently is under considerable White House pressure to guarantee a "cost effective" system, things have been reached a stage where certain major decisions of the past just can't be reversed willy-nilly. What is needed now, along with the data to come from the task force and some old-fashioned patience and understanding, is more explicit administration support for a transportation plan that will not shatter the tremendous regional interest and investment in Metro since its inception.