AS WE RECALL THE EVENTS that led to the revival of passenger train service from Norfolk across southern Virginia and West Virginia to southern Ohio two years ago, not many people were sanguine about its chance for success. Amtrak warned that it foresaw substantial deficits on the route. But the trains went into operation anyway, largely because some members of Congress from West Virginia regarded them as a vital service to their home state. Well, the two year experimental period given to the "Mountaineer," as the train is known, is about up and Amtrak's warnings have been borne out. During its last 12-month reporting period, the Mountaineer lost $3.8 million. It averaged 35 passengers a day.

The decision on what to do about this train rests with Secretary of Transportation Brock Adams. On its merits, that decision ought to be easy. Derail it. Government can and should subsidize some railroad passenger service. But it ought not to put up almost 80 per cent of the cost of running trains on any route.

Whether Mr. Adams will decide to put the Mountaineer out of its misery is another question. Amtrak, supported vigorously by some members of Congress from you-know-where, is thinking about rerouting the train so that it runs from Southern Ohio to Washington instead of to Norfolk. That would provide additional service between Washington and Richmond and revive direct service from Washington to Roanoke and southern West Virginia. But whether there is enough potential traffic in such a market to justify a train is an open question. We, at least, have considerable doubt about it.

The lesson of the Mountaineer is a simple one. Passenger trains ought to be run along routes that a considerable number of people are likely to travel. It may be that Congress has already begun to learn this lesson. It rescinded last year a 1973 order that Amtrak establish one new, "experimental" route each year. But if the lesson hasn't been learned fully, the experience of the Mountaineer -- the first of those experimental trains -- ought to drive it home.