JUST AS SURE as there's a broken Farecard machine at your nearest subway station, there's a fare increase in the cards fairly soon--though not so soon as Metro officials had hoped. Right now, they're fighting over how much to charge for rush- hour train rides and--here's the sticking point--on what basis to calculate charges. Should short-distance riders pay more per mile traveled than long- distance riders, or vice versa? Metro board members from Maryland, where the longest ride of the scheduled 101-mile system is being built, want more mile for the buck; District members want higher long-distance fares; and Virginia members have been straining for a compromise.

These jurisdictional fare battles are nothing new to Metro, though this one is rougher than usual. There is agreement on some issues: an increase in the basic bus and subway fares to 75 cents, and higher fees for crossing bus zones. But Maryland wants to keep the current rush-hour 13-cents-a-mile rate for travel beyond three miles. D.C. wants to raise it to 15 cents, which is what Metro's staff recommended. Each additional cent brings Metro $800,000 a year--which in turn reduces the amounts local governments have to pay to support the system. 4 Were it not for the long and complicated history of Metro and its three-dimensional, logarithmic, geopolitic fare structure, the answer would be--and maybe in the next century will be--a simple two-zone flat-fare system: so much for a certain distance, and so much more for the rest. Add to that a regional tax to pay for transportation and a reorganized agency to run transit, and things might go more smoothly.

But for now, when every week of indecision on an increase is costing an estimated $250,000 in fare revenues, there is room for compromise, even if it means complications. For example, some members have been thinking about a 15-cent mileage fee with a maximum fare limit of $2.25--the cost of a one- way ride between New Carollton and National Airport.

This kind of approach beats any more extended debate over who bears a greater burden: the riders who take the longest trips (in the suburbs) or the jurisdiction with the most subway users (call it wear and tear). What neither Metro nor its taxpayer/rider public can afford for much longer is delay on a decision.