Rep. James P. Moran Jr. (D-Va.) had his first philosophical collision on Capitol Hill yesterday morning. The trouble is, it happened when he rammed his car into another.

Moran was headed for his first day on the job -- he was one of three freshmen House members from the Washington area sworn in to Congress at noon yesterday -- when he collided with a car in rush-hour traffic. He barely finished apologizing when the driver whose car he hit turned to politics.

"Her major concern was getting me to change my position on abortion," chuckled Moran, who favors abortion rights. "I said, I'm not sure this is the time or the place."

Yesterday, the buoyant mood on Capitol Hill survived far worse than a fender bender. Moran, Rep. Wayne T. Gilchrest (R-Md.) and Del. Eleanor Holmes Norton (D-D.C.) were among 43 new House members who took office yesterday, and not even rumors of war could stop parties and celebrations from blossoming all over town.

Gilchrest, who represents Maryland's sprawling 1st District on the Eastern Shore, sponsored an all-day open house in his new quarters in the Cannon House Office Building. Norton and two other black women elected to the House in November were guests of honor last night at a gala hosted by Rep. Cardiss Collins (D-Ill.), the other black woman in Congress.

But Moran, who has said that joining the House was his ultimate political ambition, turned his inaugural day into a real blowout.

So many of his relatives arrived from the Boston suburbs that Moran hired a bus to chauffeur them around.

Last night, about 800 people were expected to attend a $50-a-person celebration and fund-raiser for Moran at an Alexandria hotel. Moran aides said the event would raise $40,000 for his campaign, which is about $100,000 in debt.

The guests were expected to include new District Mayor Sharon Pratt Dixon (D) and Virginia Lt. Gov. Donald S. Beyer Jr. (D).

Throughout the day, the normally staid corridors of the Capitol were the site of countless family reunions and impromptu political rallies. Gilchrest spent his first House floor session with his daughter, Katie, seated beside him.

He heaped praise on "the good, solid decent bunch of people who worked three years to get us here."

Norton, pointing out that the House's least desirable offices go to the most junior lawmakers, joked about her cramped space in the Longworth House Office Building. "I've got an office made for a freshman," she laughed. "It says freshman on the door."

Moran, who carried his 18-month-old son, Patrick, to his swearing-in, said, "There's just a surge of emotion sweeping over me. I'm humbled, because I'm not sure I have the personal resources to do the kind of job I want. But I'm determined to do the best I can. I'm not going to disappoint the people of Northern Virginia."

The first-day festivities were long on congressional pomp. Every freshman House member was sworn in at least twice; the first, official oath was administered in the House chamber with all 435 members, while the second ceremony was staged for television cameras in a private office. Both Norton and Moran took a third oath at parties last night.

For all three House freshmen from the Washington area, yesterday's festivities followed arduous campaigns in which their chances of victory were uncertain at best.

In a 13-county district that covers Southern Maryland and the Eastern Shore, Gilchrest survived a chaotic, eight-candidate Republican primary and then defeated Rep. Roy P. Dyson in the general election. Dyson had narrowly beat Gilchrest in 1988.

Norton was an early favorite in the D.C. delegate race, but her campaign was battered by revelations that she and her husband, Edward, failed to pay personal D.C. income taxes for eight years.

Moran upset six-term GOP Rep. Stan Parris in Northern Virginia's 8th District.

The only somber note in yesterday's celebrations concerned the possibility of war in the Persian Gulf. Both Norton and Moran said they would not vote to authorize offensive military action by American forces there, while Gilchrest said he would give President Bush the authority to intervene when he chooses.

Gilchrest said, "The president has been on target to this point, and Congress need to show in a resolution that we support the president."

Moran countered, "I don't rule out {military action}, but I don't think it's time to put American soldiers at risk."

But perhaps the most partisan clash yesterday involving any of the Washington area freshmen occurred on the Southeast Freeway near the Capitol, when Moran, who was alone in his car, rammed into the car in front of him.

The car that Moran hit was driven by Laurie Snow Turner, press secretary for Sen. Jake Garn (R-Utah).

Turner lives in Moran's House district, opposes abortion, and was familiar with the strong abortion rights stance taken by Moran in his campaign.

"Just kidding," Turner said. "I told him it was punishment because he campaigned so hard for abortion. God works in mysterious ways."

Both Moran and Turner emerged from the incident unhurt and apparently unmoved. "I drove on to work," Moran said. "Rush hour with a couple hundred cars behind you is not the best time to debate."