NEW YORK -- After more than a decade of seemingly endless haggling, state and city officials here are finally prepared to endorse a drastically scaled-down version of Westway that would place a six-lane roadway and waterfront park on Manhattan's West Side.

The agreement, as outlined by knowledgeable sources, would end years of political gridlock over one of the nation's most notorious and expensive public-works projects.

It would also allow New York to tap $1.7 billion in federal transportation grants, which would pay most of the project's cost, leaving the rest available for subways and buses.

New York Gov. Mario M. Cuomo (D), who had earlier criticized the $810 million compromise as too costly, and Mayor Edward I. Koch (D) are expected to announce their support of the plan today along with other local leaders, sources said.

Westway became a symbol of poor urban planning as opponents picked it apart and it became mired in litigation.

The compromise offers something for everyone. Motorists would have a replacement for the collapsed West Side Highway. Environmentalists would see reduced traffic flow and air pollution. And neighborhood residents would enjoy a narrow 60-acre park and bicycle path along the Hudson River.

"Son of Westway," as it is sometimes called, is a mere shadow of the ambitious $2.3 billion proposal blocked by Congress, in part because it would have been built on costly landfill.

The proposed six-lane boulevard would stretch from West 59th Street to the state's modern Battery Park City development at the tip of lower Manhattan. The most costly features would be several depressed and elevated sections at crucial junctures such as Battery Park and West 42nd Street.

Curtis Berger, director of the Cuomo-Koch task force that recommended the compromise, defended the price tag, saying that the depressed road segments are necessary "to preserve the view of the waterfront."

He said the design would allow pedestrians to walk to the park without dodging traffic and ensure "that cars and people are not competing for the same space."

Supporters say the depressed parts of the road would also reduce pollution from auto emissions by ensuring that traffic does not back up at busy intersections, as is often the case on the local streets near the site. New York is one of the worst violators of federal air-quality standards for urban areas.

Berger, a Columbia Law School professor, said opponents must realize that the roadway "is part of a package that also includes the development of a waterside park."

Cuomo had criticized the planned $100 million park as too expensive, saying that the money would be better spent on housing or mass transit. But he decided to endorse the plan after state officials suggested new ways of scaling it back, such as limiting the number of depressed segments. The state must contribute $120 million in matching funds.