ACCORDING TO A seven-month study of Metro's bus routes, suburban commuters are getting the best service while their in-city counterparts are being taken for the worst rides. But a look at the findings of this study, which was conducted by The Washington Post with the cooperation and help of Metro, indicates that the fault lies not in geographical prejudice but in the history of local bus service, the equipment being used and physical conditions in each jurisdiction. That said, the discrepancies should not continue. There are ways to narrow the differences.

Of Metro's 10 most reliable routes, ranked by trips missed or cut short, eight served the Virginia suburbs and one the Maryland suburbs. Of the 10 worst routes, eight ran entirely in the District. In general, buses serving Virginia riders completed all but 0.5 percent of their scheduled trips, and Maryland's buses all but 1.3 percent. D.C.'s buses missed 2.2 percent, while the average for the whole regional bus system was 1.7 percent. The best routes missed not a single trip, while the worst missed up to 7.1 percent of trips. Why?

Equipment. D.C. buses get heavier punishment: longer daily use, more miles, worse traffic and rougher roads. How about switching more vehicles around?

Maintenance. Suburban garages are newer, better designed, more attractive to veteran mechanics who choose to work in them. Surely incentives can be found to permit the shuttling around of mechanics--and how about doing the same with buses?

Many of these differences stem from the original separate bus systems inherited by Metro in 1973. Officials acknowledge that Metro has been preoccupied with rail construction, but now the emphasis must be more balanced. For that matter, the bus routes themselves should be in for major surgery and alteration to coordinate still more with subway service.

The study also points to another move that could improve in-city service. The only D.C. route to make the 10-best list was the W2--a short-distance, peak-hour loop through a Southeast neighborhood. The buses used on this route are the smaller vehicles that used to run the "Downtowner" routes. Metro says these buses are mechanically more reliable. So in addition to shorter routes, couldn't more of these little buses be fielded?

We know--money doesn't grow on buses and things can't always be changed overnight. But Metro general manager Richard Page and the local officials around the region who run the system now recognize the need for new attention to bus service --including consideration of spinning off some routes to locally operated systems. Ridership is suffering, and that recognition needs swift progression to new ways of doing things that will produce more reliable public transportation throughout the region.