A new $400 million proposal for redevelopment of the New Haven Coliseum site would move Gateway Community College and the Long Wharf Theater to the space, build a new hotel and convention center, construct a row of shops and eateries, and create a park or plaza in the center with lawns and a proposed skating rink.

“The central idea is that we are trying to create a big new outdoor room in New Haven,” said Richard Munday, a partner in Herbert S. Newman and Partners, the architecture firm that designed the plan. “It would be like Wooster Square but more urban in character.”

But current students should not plan on holding their graduation parties at the hotel. At best, the proposal will be fully implemented in five or six years.

Munday said the design was only “a diagram of possibilities” at this point, an idea instead of actual architecture. He said the company that will own the hotel on the site and perhaps the retailers running the stores and restaurants may make design changes.

“There will be an evolution in its design,” Munday said.

Tony Rescigno, the president of the Great New Haven Chamber of Commerce, said the development should have “a very positive impact” on the city. He said the Long Wharf Theater and Gateway Community College would help bring people downtown and the new hotel could fill the city’s need for more first-class accommodations, since the Omni is often sold out.

Rescigno said he thought it would take six months to a year before the Coliseum is demolished and the first new building is constructed.

The new hotel and convention center and the new Long Wharf Theater will be constructed on the site of the current Coliseum itself, and the hotel, located across the street from the Knights of Columbus museum, will serve as one end of the proposed park. The entrance to the new hotel will be a “winter garden” — a steel and glass structure containing coffee shops, restaurants and other businesses that will serve both the community and hotel guests, Munday said. Under the proposal, the theater would be located across the street from the hotel, next to the Knights of Columbus building.

Gateway Community College will stand at the other end of the proposed park, across Church Street from the Knights of Columbus building. Munday described the park as “a kind of outdoor campus” for the college, which, like Yale’s Cross Campus, would also be a place for community use.

The plan also calls for the building of a new line of shops and stores along George Street on the northern side of the plaza, along with new apartments.

More parking is also in the works.

Munday said the design will be implemented in individual parcels, with market conditions determining what is built first. He said the community college is fairly advanced in its planning and the market is good for housing right now, but the hotel and convention center will probably take longer.

“It would largely be driven by the timing of the individual projects,” said New Haven Mayor John DeStefano, Jr. “We would probably seek to do the central plaza first.”

The state still has to approve funding for the demolition of the Coliseum but the mayor said he was “very optimistic” about getting the necessary funds.

Munday estimated the total cost of the project at $300 to 400 million.