Even if a threatened nationwide railroad strike is avoided before Wednesday's deadline, this latest labor-management dispute in basic transportation still should teach some valuable lessons.

One lesson is just how important America's railroads still are even though they carry much less freight and fewer passengers than they used to.Another lesson is that this nation still needs to improve its machinery for resolving such disputes before they deprive the public of essential goods and services.

If the threatened strike materializes on schedule, the unions insist it will affect only a few railroads and no passenger service. The trouble with that claim is that the largest railroads have decided to treat a strike against one of them as a strike against all, shutting down the entire industry. Besides, since passengers travel over some routes carrying freight, some 130,000 rail travelers could not avoid being affected by the closure of those routes.

Even if only freight were involved, a nationwide rail strike could be crippling. Railroads still handle about 37 percent of the nation's freight tonnage. A strike lasting more than a few days could have a serious effect on such industries as cars, coal, grain, chemicals, steel and forest products.

Moreover, an exorbitantly costly settlement could impede the railroad industry's efforts to capitalize on the deterioration of the nation's highways by persuading more manufacturers and shippers to switch from trucks to trains.

So serious, in fact, is a nationwide railroad strike that Congress has stepped in before and legislated their settlement.

But it wouldn't be necessary for Congress to get into the act if only labor and management would agree in advance to submit their disputes to binding arbitration after other efforts have been exhausted. The usefulness of binding arbitration ought to be particularly apparent in disputes like the current one, where the nation's 300,000 railroad workers have gone without a new contract for three years.

Binding arbitration need not be harsh or arbitrary. It should be used only in those cases where labor and management seek it or when a strike threatens a national emergency. Often, labor and management are only pennies apart on wages. A binding settlement could be replaced if labor and management subsequently came to an agreement of their own through normal collective bargaining. Consequently, the prospect of binding arbitration could provide an extra incentive for an earlier settlement.

Certainly there has to be some better way of settling labor-management disputes than the railroad industry's current three-year-long exercise in foot-dragging.