IN SENDING its railroad deregulation bill to Capitol Hill on Friday, the Carter administration said the nation's railroads are in "critical" financial condition and are "struggling for survival." This legislation, Transportation Secretary Brock Adams claimes, "could be the last chance" for the railroads to compete profitable with trucks and barge lines.

Not many people in the railroad business -- or anywhere else for that matter -- will dispute his despute his description. The industry, as a whole, is in terrible shape. Without a drastic overhaul, most of it seems destined to go the way of the eastern railroads into which the federal government has already poured $2 billion through Conrail.

That's why this deregulation bill goes to Congress on a wholly different foothing from the administration's airline deregulation bill, which passed last year, or its long-delayed trucking deregulation. These aroused fierce industry opposition. Most of the railroad industry's leaders, howere, have come to regard deregulatiom as the only long-term alternative to nationalization. The result is that they want to be completely free of government control -- pretty much the opposits of the airlines' and the truckers' positions.

The railroad industry promptly objected that the administration's proposals do not go far enough. They want compete, not partial, freedom to set rates and to merge one railroad with another. other objections will be presented to Congress later. Some shippers fear that the administration's proposals will permit freight rates to go too high, too fast, and some communities will object to provisions that clear the way for railroads to abandon lightly used lies.

The balance the administration has struck -- phasing in rate dergulation over five years, leaving some limits on line abandonment, and putting rail mergere under the antitrust laws -- seems reasonable enough to us. The sudden jolt that immediate and complete deregulation might give the economy would be hard to absorb and is just about the last the economy needs just now.

If deregulation of the railroads and trucking companies could be accomplished simultaneously, the railroad argument for more rate-setting freedom would be stronger. The tow industries are entwined, and what Congress authorizes for one has a marked effect on the activities of the oyher. The general assumption is deregulation will mean higher freight rates on the railoads but lower rates on trucks. Taken together, the two probably balance out. Since it seems unlikely that a trucking bull can be passed this year -- the administration is haveing a hard time getting its act together, and the fight in Congress will be long and bitter -- passing a limited railroad bill now is the best it can hope for.