"It's the same suit. We've just gone back and done our homework," Stephen Gay, spokesman for the Red Line Alert, a citizen's group which is seeking an injunction in federal district court to halt work on the extension of the Red Line through Harvard Square, said this week.

Gay's assessment of the suit--filed jointly by the Alert and the City of Cambridge--is an accurate one. What Cambridge is seeing is a redux of the activities of the fall, although this time, analysts in the city predict the suit may actually succeed.

Gregor I. McGregor, attorney for the defendants, said he has requested an initial hearing in U.S. District Court to be held on April 17. McGregor said the focus of this latest suit is on new environmental issues. NEWS ANALYSIS

The Perini Corporation, the Massachusetts Bay Transit Authority's (MBTA) contractor for tunnel construction, plans to dig an 80 by 40-ft, hole, known as a "haul shaft," at the corner of Garfield St. and Mass. Ave. Cambridge residents have turned long-standing complaints about this shaft into affidavits for the suit as part of its new focus.

The suit charges the MBTA with substantially deviating from the original Environmental Impact Statement (EIS), which had not considered the removal of 90 per cent of the dirt for the Harvard-Porter Square tunnel from the hole on Garfield St. The suit demands that the MBTA prepare a new report.

The citizens filing the suit charge the MBTA, the Urban Mass Transportation Authority (which allocated nearly half a billion dollars for the extension) and the contractors with violating the National Environmental Policy Act, the Department of Transportation Act and the Urban Mass Transportation Act.

The suit also focuses on a report prepared by a geo-technical consulting firm which indicates that "extensive deposits of very corrosive acid sludge lie directly in the path of the proposed Red Line extension tunnel," an affidavit filed by the Red Line Alert states. The defendants claim the original EIS does not mention the problem of the acid sludge.

Joseph Elcock, general counsel for the MBTA, said Monday he has not yet been served to appear in court. "To my knowledge, we are complying with the EIS," Elcock said.

Meanwhile, city officials and residents are criticizing Harvard for negotiating what the major's office calls a "sweet-heart deal" with the MBTA for almost $1 million in compensation for necessary construction work in and around Harvard Yard.

"Harvard has been conspicuous with its absence," Bernard Flynn, administrative assistant to Mayor Thomas W. Danehy said, adding, "They come out on top, no matter what they do."

Residents seem ready to renew the court battle. "The MBTA envisions itself to be at the papal seat of transportation," says defendant Henry J. Shawah. "They've never been dragged to court before but that's not going to stop us."