FOR OLD TIME'S sake and regionalism too, Metro officials have reason to be pleased that their runaway partner of nearly three years ago -- Fairfax City, which picked up its stakes and got off the bus system in a huff -- is returning to the system. Though it's good to have all the participants back in the transit negotiation, the issues are more important than ever -- with no good solution obvious. The danger remains that other financially frightened partners may try to leave the system unless something is done about transit costs. That would be a wrong and expensive reaction, but something's going to have to give besides strapped local governments.

Any examination of what's driving up costs could start right behind the wheel of any bus: Metro's drivers and other union employees enjoy one of the best -- if you're a taxpayer, make that read most expensive -- cost-of-living provisions in any contract. Metro officials still don't know how much the next contract decision, expected a month or so, will run, but it's sure to be more than loose change. Higher fares and bigger government contributions can only go so far in covering these quantum leaps in costs; and though the contract provision lives on, thanks to the federal tradition and bargaining procedures that produced it, employees had best not ignore what could be the next consequence of their generous contracts: severe cuts in service, which means jobs -- and never mind any public wrath that may come the union's way.

No one is seriously advocating cruel or unusual financial punishment for Metro employees; but neither are others struggling to stay even with inflation able to afford greater protection than they themsleves enjoy. For Metro and the people it serves, the balance of routing, fare schedules and local government payments is extremely delicate -- and unless there is an adjustment to reflect the cost of labor in the cost of living, the whole region is going to lose.