Subway With a Park on Top. Boston's Southwest Corridor has train tracks below, green areas and recreation above. URBAN DESIGN: MASS TRANSIT

IF you walk along the green ribbon of parkland that runs between the South End and Back Bay sections of Boston, and watch neighborhood kids slam-dunk basketballs, yuppies lob tennis balls, and strolling couples walk dogs, it's hard to believe that right below all this neighborhood fun lies some serious transportation: Amtrak, commuter rail, and rapid-transit trains. Welcome to the Southwest Corridor, a massive $747 million transportation project that took 13 years to complete and is winning kudos for its responsible urban design. The latest was a Presidential Design Award, one of the top 10 of the 68 Federal Design Awards, given by the National Endowment for the Arts to exemplary federal design projects. Given last month, that award not only commends the project for its design but also its knitting together of four diverse neighborhoods. The jury citation acknowledged that ``the planning process is one of the most intensive public participation projects in the history of mass transportation.''

Allison Fouts, property manager for federally subsidized housing abutting the park, walks along the park from the station to her job. ``There's little plots where people do some gardening. And it's so clean, people are always taking care of things. I always found it to be a very pleasant promenade.''

Twenty years ago, this was a wasteland, a 120-acre vacant lot awaiting a planned freeway. A thousand houses had been bulldozed before community opposition killed the plan in the late '60s. Over the next two decades, a concert of neighborhood groups, working with government transportation authorities, came up with a plan that took down the nearby elevated rapid-transit Orange Line, moved it in with commuter rail trains underground, and established a linear park on top.

The project included a training program that introduced architecture, landscape architecture, and engineering as career options to hiarcels to provide employment to replace jobs lost to land clearance, says Dee Prim, now a community liaison with Frederic R. Harris, an international engineering firm in Boston.

Getting all of this through the bureaucratic maze meant years of meetings for community residents. ``Did I go to lots of meetings you ask?'' hoots Edwina (Winkie) Cloherty, who during that time was raising two children.

``At least once a week. But it was a positive thing, no doubt. Because other friendships have been formed, and we certainly learned how to make government more responsive in a constructive way. There are people now very sophisticated in what the community process should be.'' Mrs. Cloherty is now a transportation planner with the city of Boston.

Citizen activism meant the difference when funds for the project were in jeopardy in 1976, says Ms. Primm, then a community liaison with the Southwest Corridor Land Development Coalition. ``If members of the community had not flown to Washington with state and city representatives, there would not be a Southwest Corridor.''

Today, the 4.7-mile corridor snakes through Boston with bike trails, footpaths, tot lots, an amphitheater, a hockey rink, and open fields. Ridership on the sleek new Orange Line is up 20 percent. With the noisy elevated gone, property values along the old route have gone up. And parcels of land are available for development.

Now, other major development projects in the Boston area are ``looking here for lessons to be applied to their project,'' says M. David Lee, a partner with Stull & Lee, one of the nine architectural and urban design firms that worked on the project.

Stull & Lee won a Presidential Design award for its urban design process and coordination of station architecture. Besides designing one of the stations, the firm created a handbook for design and architectural criteria. Involved in the project from the beginning, the firm was brought in by the community as a bridge to the larger municipal forces. ``We explained the process in terms ordinary people could understand,'' Mr. Lee says.

``In some of the hearings, one of the things we pointed out was that we're going to spend all this money to build this limited-access highway, basically destroying the neighborhoods ... all to save some commuting suburbanites a few minutes off their trip,'' he said. ``It was felt that the neighborhoods were paying too heavy a price for that, and that the commuter rail, mass-transit, and development opportunities were a better investment.''

Dan Ocasio, who headed a Massachusetts Bay Transportation Authority special office to handle the Southwest Corridor project, chaired more than 1,000 meetings from 1977 to 1987. The process, he says, was a model of high-level community participation.

``The community [members] learned they can be effective and influence process in terms of incorporating their comments and securing any changes they may have wanted into the process. They were exposed to technical jargon, and many of them came away with knowledge about planning and development.''

During this decade of meetings, the demands of each neighborhood were thrashed out. The South End, which had the corridor right in its backyard, insisted that trains be underground. Roxbury, which was slightly farther away, did not object to the trains being aboveground but wanted facilities for kids. The Jamaica Plain and South End neighborhoods didn't care about children's areas, but were big on gardens.

Entering a community galvanized into action by this project, as well as the general activism of the times, was a eye-opening for some of the outside engineers who came in to work on the project, Lee says. ``They began to realize it was easier to work with and accommodate the interests of these groups than to fluff them away. It went from an adversarial relationship to one of grudging cooperation to real respect.''

Mr. Ocasio says the activists forced the state to reevaluate plans for the whole region, and that was the first time the federal government was willing to allocate highway dollars to rapid transit.

``I think one of the real watersheds was when UMTA [Urban Mass Transportation Authority, a federal agency], the highway [officials], and everyone else realized it was not a transportation issue,'' Lee says. ``It was a community project with a transportation component. There were historic, environmental, development, civic components. Once you see all of that as a larger development issue, then the waters parted, so to speak. ''