The Urban Land Institute issue on Union Station's potential yesterday, telling Amtrak basically what it wanted to hear: that the station could be developed successfully to provide shops, restaurants and other services for rail passengers, neighborhood residents and tourists.

But the report, prepared for the institute by a panel of developers, was prefaced with a caveat, saying that it would only work if the various agencies involved in the railroad station's operation would pull together under one leadership.

If the station "continues to be divided into separate pieces by agencies with separate purposes, it will be a continuing disaster," said the panel's chairman, Donald R. Riehl, a California developer. Riehl also noted what thousands of train passengers have observed: The hodge-podge of a train station and a visitors center is "inefficient and inadequate as laid out right now."

The panel said that although commercial development of the station might be financially successful, it would not generate enough money to restore and maintain the entire historic structure. Nor should it be expected to, the panel said.

The study by the Urban Land Institute -- a nonprofit organization that sends squads of land-use planners into various sessions on particular problems -- cost Amtrak $40,000 and was part of an initiative to develop the train stations it owns or leases.

In the case of Union Station, commercial development depends on passage of legislation pending in the House of Representatives that would turn the building's concourse back into a train station.

The report generally stayed away from specifics about what shape eventual development of the train station might take, saying that decision should be left to a private developer chosen to carry out the grand plan. But here and there it gave clues to what might be done, talking about the possible commercial development of a largely unused lower level or mentioning types of shops -- such as art galleries or an American craft shop -- that might find a home there or restaurants that might serve American regional cuisine.

Among its concrete suggestions for the building itself, the group recommended bringing the railroad tracks back into the concourse -- a step already approved in the recent passage of legislation providing for improvements of the Northeast rail corridor -- and providing adequate parking either by completing an area left unfinished or by finding a less expensive area.

The group also opposed moving intercity bus terminals -- Greyhound and Continental -- into the station. The bus terminals eventually must move from the old downtown area to make room for development around the convention center.

The National Visitors Center was built in the early 1970s, resulting in the removal of the train station to a temporary terminal behind the concourse. Although the center opened July 4, 1976, some 400 parking spaces, a ramp and a raodway circulation system never were completed.