WASHINGTON (AP) _ The Supreme Court today barred Texas officials from requiring cabooses or alternative safety equipment on most trains traveling through the state.

The court, without comment, let stand a ruling that federal law preempts such state regulation.

The Texas Railroad Commission in 1986 adopted a rule requiring cabooses capable of communicating with the locomotive on all trains carrying various hazardous materials and on trains more than 2,000 feet long that lack mechanical devices for monitoring the train and track.

The regulation was designed to allow someone in the caboose to make sure brakes, axles and wheels are not overheating and to check for any problems behind the train.

The 5th U.S. Circuit Court of Appeals threw out the rule last July. The appeals court, noting the safety aspects of cabooses generally have been supplanted by technological advances, said the Federal Railroad Safety Act of 1970 preempts the state's regulation.

Cabooses once were essential to train operation in the days when brakes were located there, the appeals court said.

But now, it said, ''Automatic brakes are controlled from the locomotive, advances in wheel bearings decrease the risk of overheating and monitoring devices simulate rear-car observation.''

Major railroads, through collective bargaining with their unions, in 1982 eliminated cabooses from about one-fourth of all trains.

The 5th Circuit court said Congress, in passing the Federal Railroad Safety Act, determined that cabooses do not involve safety. The issue is one for collective bargaining, the appeals court said.

''Under these circumstances, we are compelled to conclude that the (act) has impliedly preempted state regulation of cabooses,'' the appeals court said. Requiring cabooses in some states would burden interstate commerce by forcing the railroads to attach cabooses at all times or stop at state borders where they are required to attach them, the appeals court said.

Texas regulation permits railroads to avoid the need for cabooses by installing load and overheating detectors and other devices along the track.

But the appeals court said the requirement for those devices is preempted by federal law as well.

The Texas Railroad Commission said the 5th Circuit court ruling permits ''collective bargaining to override governmental regulation of a safety issue.''

The case is Railroad Commission of Texas vs. Missouri Pacific, 88-789.