Government lawyers urged a federal appeals court yesterday to quickly resurrect plans for a new 12-lane Woodrow Wilson Bridge, saying the region's crushing traffic demands outweigh concerns raised by community activists.

The Federal Highway Administration is attempting to get the $1.9 billion project back on track after a ruling last spring by U.S. District Judge Stanley Sporkin, who ordered that no construction can take place until a comprehensive environmental review is completed. Ruling in favor of a group of community activists, Sporkin found that transportation officials had failed to fully consider alternatives, including a 10-lane structure.

But Assistant U.S. Attorney Daria J. Zane told the appellate judges that officials acted appropriately in ruling out the 10-lane structure because of traffic concerns. Although all 12 lanes of the proposed bridge would not be used immediately, she contended that they would be needed by 2020.

The appellate judges--Laurence H. Silberman, Stephen F. Williams and A. Raymond Randolph--appeared sympathetic to Zane's arguments during a 45-minute hearing yesterday and challenged the activists' contention that a 10-lane bridge was feasible and merited further study.

"How do you justify a 10-lane bridge if by 2020 you know you're going to need a 12-lane bridge, and the cost of retrofitting is astronomical?" Silberman asked S. William Livingston, an attorney for the activists. When Livingston replied that a 10-lane bridge could carry almost as much traffic throughout the day, Silberman retorted, "At a slower rate."

Williams pointed to an analysis showing travel delays cut nearly in half during peak periods under the 12-lane proposal. Such a difference, he said, "could certainly be found by a road builder to be significant." Randolph agreed, suggesting that a 10-lane bridge "is not an alternative if it doesn't accomplish the objective of the federal action to begin with."

Sporkin's decision was hailed by the Coalition for a Sensible Bridge and other Alexandria activists who filed suit to block the project. But the ruling alarmed federal, state and local transportation planners, who warned that the heavily traveled 38-year-old bridge is deteriorating so rapidly it could be closed to heavy truck traffic within five years.

The legal battle then shifted to the D.C. Circuit Court of Appeals, which put the case on an expedited schedule. None of the judges yesterday quarreled with the need to replace the current six-lane crossing over the Potomac River. The bridge, designed for 75,000 vehicles daily, now carries roughly 160,000 a day and by 2020 will carry 300,000, officials said.

Lawyers on both sides said they expect a decision by the end of the year. If Sporkin's ruling is overturned, officials said work could start on the 12-lane bridge by late next year and the first span of the project could be completed on schedule by 2004. If Sporkin's ruling is upheld, construction could be delayed for a year or more, officials said.

The City of Alexandria initially joined activists in the suit, but dropped out after striking an agreement that provided for design improvements.

Livingston told the judges that the government had a duty under the National Environmental Policy Act to fully consider a 10-lane version of the bridge and then contrast its impact upon the surrounding environment with the effects of a 12-lane span. He also argued that the government didn't follow rules in weighing the project's impact on historic sites in Alexandria. Zane countered that officials considered a 10-lane bridge but later ruled it out.

The appellate judges' remarks raised hopes of lawyers for the Greater Washington Board of Trade, who filed briefs seeking a reversal of Sporkin's ruling. The Maryland and Virginia governments also filed briefs backing the 12-lane bridge, as did Prince George's and Fairfax counties.

But Bert Ely, a leader of the Coalition for a Sensible Bridge, said the courts aren't the only obstacle facing 12-lane advocates. Noting that additional federal money is needed, he said, "No matter what happens on the appeal, you'll still have the funding issue."

CAPTION: An artist's rendering shows the proposed design of an $1.9 billion, 12-lane Woodrow Wilson Bridge.