President Clinton yesterday signed legislation that repeals federal speed limits, putting aside concerns that faster drivers will lead to more highway fatalities.

At 12:01 a.m. Dec. 8, states will be able to set their own speed limits, which in some western states will automatically go up to 70 mph or higher. Two decades ago President Richard M. Nixon signed legislation that lowered the national speed limit to 55 mph to save energy during an oil embargo.

Clinton signed the legislation, which had overwhelming support in Congress, despite a last-minute veto campaign by safety, environmental and insurance groups.

White House spokesman Michael McCurry said Clinton is concerned that higher speed limits will lead to more highway fatalities, but "there's not a certainty that any veto that he would exercise would be sustained by the Congress."

Next week states will be able to set any speed limit, free of federal rules that require a maximum 55-mph limit on all highways except for some rural freeways where 65 mph is permitted.

Speed limits were only one part of the legislation that designates a new 160,955-mile National Highway System (NHS), essentially a map of the country's most important roads. To help create the system, Congress in 1991 voted to cut all federal funding for the roads at the start of the 1996 fiscal year on Oct. 1 if the NHS bill had not been signed.

McCurry said Clinton's decision was prompted by concern that $6.5 billion in highway funds had been held up for almost two months, and "necessary highway improvement projects" could be delayed.

As the bill was being debated, several popular amendments were attached to it, including full federal funding to refurbish the Woodrow Wilson Bridge -- the Beltway's span across the Potomac River south of the District -- and studies for a new crossing that would ease the Wilson Bridge's bottleneck.

Ownership of the bridge, the only interstate bridge the federal government owns, will be transferred to Virginia, Maryland and the District.

The Wilson Bridge amendment, pushed by Sen. John W. Warner (R-Va.), was the only new highway project in the bill.

Future legislation will determine the federal government's share of construction costs for a new bridge or tunnel, while the federal government renovates the current bridge.

Given the changes in speed limits, debate over the bill was dominated by safety issues, although the legislation calls for several changes in transportation law.

The Clinton administration and safety groups were surprised by the strong support to end federal speed limits, first imposed in the wake of the 1974 oil embargo by the Organization of Petroleum Exporting Countries (OPEC), which brought long lines at gasoline stations.

Transportation Secretary Federico Pena initially opposed changing the speed limit, but quickly lost ground to Congress.

Ultimately, the administration was able to do little more than tinker around the edges of the bill.

The speed limit change becomes effective in 10 days.

Most states will not automatically return to pre-1974 speed limits, but the issue is likely to be taken up by many state legislatures.

Eight states, including California and Texas, already have passed laws that will allow drivers to drive at 70 or 75 mph.

And Montana, which like most Western states has thousands of miles of wide-open flat roads, will have no speed limit.

The speed limit is one of the country's most ignored laws, especially in the West. Surveys, however, show that the public is not as enthusiastic as its elected representatives over higher speeds.

The American Automobile Association says that 85 percent of motorists in a survey indicated that they think the speed limit on interstate highways should be 65 mph or lower. And 47 percent said they believed the federal government should continue to set limits.

Safety and environmental groups railed against the bill, citing Transportation Department studies that attribute 6,400 additional deaths a year and $19 billion in increased health costs to speed limits over 55 mph. Yesterday, consumer activist Ralph Nader said that Clinton joined Congress in killing Americans.

"History will never forgive him and his allies in Congress for this assault on the sanctity of human life," Nader said.

Brent Blackwelder, president of Friends of the Earth, said higher speeds will waste energy, pollute the air and kill Americans at the same time that Clinton is sending troops to Bosnia to stop the slaughter of Europeans. "That is not moral leadership or moral consistency," he said.

Others view such criticism as overblown. "Obviously we will be closely monitoring the effect," a Transportation Department spokesman said. CAPTION: ROLLING BACK TO HIGHER SPEEDS

President Clinton signed legislation designating 160,955 miles of U.S. highways as the National Highway System. The bill also: - Repeals the national 55 mph speed limit, enacted in 1974. - Removes penalties on states that do not require motorcycle helmets. - Removes requirement that highway signs designate distances in kilometers. - Removes requirement that old tire rubber be used in highway construction. - Allows states to erect billboards on portions of scenic highways. - Requires states to strictly enforce drunken-driving laws for drivers under 21 and lower the under-21 blood-alcohol threshold to 0.02% for drunken-driving convictions. - Provides all funds for the rehabilitation of the Wilson Bridge and planning for a new Potomac crossing. SOURCES: Advocates for Highway and Auto Safety and staff reports CAPTION: In Reno, sign-maker Willow Sullivan prepares 75 mile-an-hour speed limit stickers to be slapped on the 55 postings which expire in Nevada on Dec. 8.