Not long ago, most of the nation's waterfronts lay abandoned, cut off from pedestrians and the life of the city by strings of freeways and railroad tracks, symbols of two forms of transportation that made many ports obsolete and facilitated a population shift inland.

Vestiges of a bygone era when people and products were transported by water, the waterfronts of more recent history have been dominated by warehouses and industrial buildings, even such non-water related uses as parking lots.

Once again, however, waterfronts along the nation's coasts and rivers have become hot property, and activity--albeit a different kind--is bustling. People are working in offices along the waterfront, eating there, shopping there.

New waterfront developments are taking place in some cities one didn't even know had waterfronts. Projects are in various stages of development in Denver; Fredericksburg, Va.; Camden and Hoboken, N.J.; Portland, Me.; Stamford and South Norwalk, Conn.; Newport, R.I.; Chicago; Seattle and Olympia, Wash.; New Orleans; San Diego; Norfolk; Honolulu--name a city.

Spurred by what many think is a natural attraction to the water and by a few glowing examples of the lucrative potential of waterfront development--like Baltimore, Boston and San Francisco--every city that has any kind of waterfront now seems to want, and is setting about getting, new and revitalized waterfront development.

"The real danger is homogenization," David A. Wallace, a partner in the Philadelphia firm of Wallace, Roberts & Todd, warned at a recent Urban Land Institute conference. "There is a very real problem that all the waterfronts will begin to look alike, instead of retain their unique character."

The two-day ULI conference on urban waterfront development, held appropriately in Alexandria near its waterfront, attracted city officials, planners, architects and developers from as far away as Juneau, Alaska. Those with plans in mind or on the drawing boards got pointers from those with successful projects to talk about, including pointers on dealing with some special problems waterfront developments entail.

Waterfront projects are a lot more complicated that good old-fashioned non-waterfront development. Besides the same economic and financial considerations, there are new factors. One is that more than one government jurisdiction often is involved, noted Douglas M. Wrenn, a ULI associate and author of Urban Waterfront Development.

Constraints cited by Arthur Collins, president of Collins Development Corp. in Stamford, Conn., include the limited availability of waterfront property; the rising price of the land that is available; separation of an often-dilapidated waterfront from the city center; zoning difficulties; environmental impact requirements; Corps of Engineers authority; flood-plain considerations, and even the tides.

L. Michael Krieger, manager of waterfront development for the Port Authority of New York and New Jersey, warned that a minumum of ten years may be required for major waterfront development. Flexibility, politics and consensus-building among groups with competing ideas are required. "You need long-term staying power," Krieger advised.

"We look for developers who are able to spend substantial amounts of front money and are ready to absorb the starts and stops of public policy," said Martin L. Millspaugh, who coordinates Baltimore's Inner Harbor Development. He also added bidding, affirmative action and historical preservation rules to the constraints, and the fact that a developer's profits will be limited when it joins with a city in waterfront development. "A few years ago, this list would have alienated developers," he said, " . . . but this is where the action is."

Scott Ditch, vice president of the Rouse Co. of Columbia, Md., cited an additional problem to overcome before Rouse could close the deal for its enormously successful Faneuil Hall Marketplace in Boston. "Going against us . . . was that we weren't from Boston, weren't even from New England; we were from below the Mason-Dixon Line--and we had developed suburban shopping centers."

The Faneuil Hall project, opened in 1976, involved saving three historic structures as part of the city's urban redevelopment, which added to the problems. Quincy Market, the first of the project's three markets to open, was built on landfill, so the tide must be pumped twice a day, Ditch noted. The 2,700 windows of all different sizes had to be hand-fashioned in Germany. Rouse also is responsible for cleaning, lighting and security of the area; it steam-cleans the streets every night the temperature is over 32 degrees, Ditch added.

Faneuil Hall was a success from the beginning. Fully leased, its business has grown 16 percent a year. Ditch said Rouse manages the place "carefully," watching for weakness in its 200 merchants. "You can't let it slide," he said. At Baltimore's Harborplace, which opened in 1980 and has had even larger growth, Rouse restricts the leases of some of its 132 merchants to 30 days, so that it can keep feeding creativity into the marketplace, he said.

The Rouse projects contain elements the firm believes are essential for successful waterfront development. For instance, all are fairly small projects. Rouse's Faneuil Hall is on 6.7 acres, Harborplace is 3.2 acres and its new South Street Seaport project in Manhattan, set to open next month, is just four blocks plus a pier. "It doesn't take much to be a catalyst," he said.

Also, there is no geographic separation between the waterfront and the urban area, so there can be a ripple effect. Proximity to a large market is important. Faneuil Hall is close to government buildings and the financial district, is accessible to public transit and has about 5,000 parking places. Baltimore's Harborplace is within walking distance of the central business district. "But if you bury it too much in office complex, you may wind up with a Renaissance Center," he said, referring to the unsuccessful Detroit project.

Rouse also believes a project should attract the local market on a regular basis, Ditch said, with no more than 30 to 40 percent of the project's business coming from tourism.

Of course, successful waterfront development benefits both the developer and the city. Of Rouse's 58 projects, two of the three projects that are most productive for the company are Faneuil Hall and Harborplace. And both cities do very well, too. Rouse pays Boston less than $100,000 a year in rent, but the city gets 25 percent of Rouse's gross revenue in the ventures. That amounted to $2 million last year, he noted.

Baltimore gets $1 million a year in revenue from Rouse, and the city still owns the land. The project also created 2,400 jobs, half of which went to people who had been on welfare, Ditch said.

A tour of the Potomac and Anacostia Rivers by boat during the conference illustrated what was being discussed. For instance, parking lots--a commercial parking lot, an impoundment lot and garbage trucks--keep the public away from much of the riverfront in Georgetown. "A great deal of negotiations is required to get these uses out," said Joseph E. Brown, principal and first vice president of EDAW Inc. in Alexandria.

One large development along the Potomac is set for construction, according to Phillip L. Ross, vice president of Western Development Corp., which now has permanent and construction financing and will begin building the $175-million Washington Harbour project in Georgetown this summer.

The mixed-use complex--a joint venture of Western Development, CSX Resources and Kan Am Realty--will include 480,000 square feet of office space, 100,000 square feet of retail and restaurant space and 120,000 square feet of residential condominium space. Already, Ross said, about half the available condominiums have been sold, at prices ranging from $400,000 to $2 million.