Vision42 — a citizens initiative that's part of the nonprofit Institution for Rational Mobility — is proposing the construction of a light rail system along 42nd Street, with stops at each avenue from river to river.

The system would be above ground and replace all vehicular traffic on the major thoroughfare, which under the plan, would basically become a pedestrian walkway.

"Practically speaking, it could absolutely be done," said civil engineer George Haikalis, who helped launch vision42 in 1999. "It's been done before all over the world."

Architect Roxanne Warren, another founder of the group, said she and Haikalis decided to pursue the plan after she took a crosstown bus ride and "went slower than the pedestrians."

"Right now, crosstown travel is impossible," she said. "The estimated travel time of the rail system would be 20 minutes."

Warren and Haikalis have already made nearly 200 presentations to community leaders and elected officials on the rail system, and they are waiting for the results of three technical studies to really get the word out.

The studies — which are being done by consultants and were funded by a grant from the New York Community Trust — are investigating economic impact on the city, cost and traffic impact.

"While many of the people who saw the presentation were excited about the idea, there were certain questions about cost and so forth," Haikalis said. "To move this thing along, we really needed some technical input."

The results of the studies will be posted on vision42's Web site on April 18 — the same day as a public forum to be held at the New York Marriott Marquis Hotel with the Manhattan Borough President's Office and Community Boards 4, 5 and 6.

"We'll have representatives of the consultants there to answer questions, so everyone interested can have their concerns heard," Haikalis said.

The idea for a rail line on 42nd Street isn't new — in 1994, the City Council voted to support a rail line on the street, but when cost exceeded what was expected, the plan died. The cost then for the rail and street repairs was about $100 million.

"We wanted to revive the plan, but also make the street a pedestrian walkway," Warren said. "It will change New York if it goes through."

According to vision42, the rail system would take six years to build and probably be run by the MTA.

City Transportation Department spokeswoman Kay Sarlin said, "We are always open to new ideas, but we have had concerns about the feasibility of a 42nd Street light rail. The Shuttle and No. 7 trains currently provide cross-town service, and the administration's transit priority in the area is the extension of the No. 7."