Safe Highways...[ ...And a Cleaner I-Way]

The federal speed limit (55 m.p.h. on most highways) imposed two decades ago at the height of an oil embargo has never been very popular. It is now a thing of the past. President Clinton has signed Congress's compromise $6.5 billion transportation bill, part of the GOP plan to shift more power to the states.

The legislation designates a new National Highway System (NHS) - 161,000 miles made up of the interstate system and other key highways. NHS, which would serve as a focal point for future federal investments, is not in itself controversial. What concerns critics - rightly so - are amendments tacked onto the bill, including one giving states authority to set speed limits (or not to set them) and another repealing penalties for those states that don't mandate motorcycle-helmet use. A pilot program exempting operators of some commercial vehicles weighing less than 26,000 pounds from federal safety laws and regulations also is worrisome.

Though put into place to conserve energy, federal speed limits have been credited with reducing highway fatalities. Higher speed limits may force insurers to raise rates, and workers' compensation costs also could rise.

A recently released study by Advocates for Highway and Auto Safety says nine states would ''automatically'' raise speed limits to 70 m.p.h. or higher on interstates and major state roads, and 28 states are ''most likely'' to raise limits to 70 m.p.h. shortly after the repeal.

The legislation frees from restrictions $6.5 billion in grants for the states in the budget and a like amount next year. But safety shouldn't be pushed to the sidelines. Sen. Max Baucus (D) of Montana, a backer of the legislation, expressed no concern about the safety-law repeal. ''Six-and-a-half billion bucks goes back to the states,'' he said. ''That's jobs, that's highway construction.''

The American Automobile Association campaigned for NHS but does not favor a federal speed-limit repeal. We join the AAA in strongly urging governors to do their homework and exercise caution in determining appropriate speed limits and other safety precautions for their states. A federal speed-limit repeal shouldn't mean no limits at all.

A speed-limit repeal on national highways shouldn't mean no limits at all.