The National Trust for Historic Preservation and seven local civic groups filed suit in federal court here yesterday to block the construction of suicide-prevention fences on two bridges over Rock Creek Park.

The suit says the planned eight-foot-high wrought-iron picket fences will "violate the architectural integrity" of the bridges on Calvert Street and Connecticut Avenue and also will "severely detract" from views of the park.

The suit also claims the D.C. government failed to follow federal laws on historic preservation and environmental protection in approving the project.

Work on one fence, along the Duke Ellington Memorial Bridge on Calvert Street, started last week.

At yesterday's hearing, lawyers for the National Trust and the seven other opponents asked U.S. District Judge Norma Holloway Johnson to stop that work, which involves drilling holes in a low concrete handrail to support the posts.

However, lawyers for the District and federal governments said all laws had been followed. They noted that plans for the Calvert Street bridge were approved last year by the District's Advisory Council on Historic Preservation and by the city's historic preservation officer, Carol B. Thompson.

Johnson questioned Edward Lee Rogers, attorney for the opponents, about their claim that the holes will cause "irreparable injury," which is a requirement for granting the temporary restraining order that the suit requests. Johnson indicated that she will probably rule on the motion today.

Fence construction on the William Howard Taft Bridge on Connecticut Avenue is planned next summer.

Both bridges tower about 125 feet over Rock Creek Park and have long been a prime location for suicides in the District. Since 1978, 33 people have jumped to their deaths from the bridges, including four so far this year.

The fence on the Calvert bridge will cost $160,000 with 80 percent of the cost paid by the federal government.

The plaintiffs in yesterday's lawsuit include the D.C. Federation of Citizens Associations, the 18th and Columbia Road Business Association, the Kalorama Citizens Association, the Woodley Park Community Association, and the Reed-Cooke Neighborhood Association. The D.C. Preservation League and the Art Deco Society of Washington also joined the suit.

Rogers noted that both bridges have been designated historic landmarks. City officials "want to punish the bridges because of an occasional suicide," Rogers said.

"What happens if someone does jump off of that bridge?" responded Assistant D.C. Corporation Counsel Robert J. Harlan Jr. "I don't think that should be called speculation."