SOMETIMES THOSE cryptic destination-listings on the foreheads of Metro's droopy-eyed buses actually do provide a tiny hint of where they may be going -- but a reading of the bus drivers' union contract tells you in no uncertain terms that every one of those drivers is heading at a fast clip for Fat City. So are all the subway operators. Not only do these transit workers enjoy a huge taxpayer-green cost-of-living arrangement unmatched in other public-employee circles, but it's all gift-wrapped in a government-guaranteed binding arbitration setup:

The Metro compact, agreed to by Maryland, Virginia, the District and Congress, requries the system's management and its unions to settle disputes through binding arbitration. Historically -- which is to say every single time, including once already this year -- arbitration rulings have left in place the generous cost-of-living provisions.

So as a result of the latest decision, Metro's bus and subway operators get automatic raises four times a year that match the rate of inflation for the first nine percentage points, then match approximately two-thirds of each additional point. The real zinger in this formula is that these increases are guaranteed -- regardless of the local jurisdictions' ability to pay.

Any change in the compact is complicated: Every word must be agreed to by the two states, the District and Congress. Virginia has already done its part this year, and Maryland has the proposal under consideration in Annapolis. Yesterday (as outlined elsewhere on this page, For the Record) Rep. Frank R. Wolf, with the cosponsorship of his fellow Republican from Northern Virginia, Rep. Stanford Parris, introduced the measure in the House. If members of the District Council are serious about controlling the costs of Metro, they, too, should follow suit. Whatever disputes may arise over the precise language of the changes can be negotiated; but immediate, positive action by all four parties is essential to stop the costs of Metro from getting totally out of control -- or reach.