IT'S STILL TOO EARLY to start whipping out the farecards, but subway riders throughout the region should be interested to know that yet another meeting is scheduled today on the fate of Metro's Silver Spring - Glenmont leg of the Red Line. As you may recall, the plans for this section of subway have become an issue threatening the entire regional financing of the Metrorail system. But today Transportation Secretary Brock Adams, Montgomery County Executive James P. Gleason and other key figures in the controversy are set for another round of talks - and, we would hope, some signal of a go-ahead for the line.

Here's the situation: In early summer, Mr. Gleason, understandably frustrated by DOT's shilly-shallying on the subject of the Glenmont line, struck back by withholding his support for the release of some $328 million earmarked for the construction of already programed segments of the Metro system. This misguided move resulted in the stopping of new Metro construction and imperiled the entire agreement to complete 60 miles of the system's planned 100-mile network.

By last month, DOT's position apparently was that the federal government would consider allocating money for the line if the local jurisdictions would give it top priority beyond the 60-mile network, commit construction local matching funds and entitlements to federal interstate money and give the project the Metro board's stamp of approval. What DOT wanted through all this, apparently, was teh strongest set of justifications it could get to make a case before the President's Office of Management and Budget that the Glenmont line would be a sound investment ("cost-effective," as they put it).

Now, as far as we can tell, DOT's conditions appear to have been met. The region, the Metro board, Mr. Gleason and just about everybody else with any stake in this line agree that it's a top priority section of the metropolitan area's proposed public transportation system. Moreover, Montgomery County already has much invested in the completion of this section: Over the years, plans for highways have been eliminated on the presumption that the subway line would be built, and planning for high-density development has been pegged to the planned subway corridors. And it isn't only MOntgomery County that cares, either; the District, too, has an interest in the Glenmont line - for neither the city government nor its constituents who happen to live near the Silver Spring area want the subway to terminate there.

Above all, Metro officials are merely proposing now that they be given a federal approval on the condition that they produce the local share of the cost. This strikes us as a compelling case for fairness, worthy of a clear federal response. In the meantime, Mr. Gleason should stop holding up the money that is desperately needed for other segments of the Metrorail network. There may be details of design and financing that remain to be worked out. But neither DOT nor OMB shuld need any more arguments for approving plans to build the line - for it is a vital link in a coordinated attempt to support an example of public-transportation excellence in the national capital area.