As construction fencing comes down and office towers go up at the World Trade Center, the entire lower Manhattan area might get at least one more improvement: a more direct ride to the airport -- but not to a New York airport.

Earlier this year, the Port Authority said it was budgeting money for an extension of the PATH train, which has a terminal at the trade center, from its Newark stop to the Newark Liberty airport shuttle, less than 2 miles away.

The move is being hailed by officials and other area boosters who have long advocated a one-seat ride to the airport.

The head of the local community board, Catherine McVay Hughes, said a more direct ride to an airport was essential to the area's, and the city's, long-term success.

"This is something that New York City, in order to compete globally, needs to have happen," she said. "All great cities have easy public transit to the heart of their city."

The proposal would be a lot simpler than what downtown residents and workers currently have to do if they want to get to the Newark airport -- taking a PATH train from the trade center to Newark, switch to an Amtrak train and then switch again to the Newark air shuttle a short distance outside the airport.

A PATH extension would be the latest change to redevelopment of the WTC site after the terrorist attacks of Sept. 11, 2001.

One World Trade Center is scheduled to open later this year and will stand as the tallest building in the country at a symbolic 1,776 feet. It was developed by the Port Authority and the Durst Organization.

Silverstein Properties is building the three other towers on the site. One of those opened last November. Construction has begun on another, but construction beyond the foundation will not begin on the third tower until an anchor tenant is found.

A one-seat airport ride directly to airport terminals has been a dream of city and regional planners for decades, but the assumption until recently has been that it would link Manhattan to a Queens airport, with Kennedy Airport being the most likely terminal.

As late as 2004, then-New York Gov. George Pataki had been touting a one-seat link to Kennedy, but the port agency decided in 2012 to explore Newark as a possibility and put $1 billion of the $1.5 billion estimated project cost in its capital budget this year.

"This is going to happen," Jessica Lappin, president of the Alliance for Downtown New York, said in an interview last week. "I'm told they've begun to plan for it. We are the only major international city without a link. The time has come."

The alliance represents businesses, including those on the WTC site, in a square mile chunk of lower Manhattan south of City Hall.

Many planning groups support the proposal, but some people who track WTC development are cautious about its prospects. Mitchell Moss, a professor of urban policy and planning at NYU, notes that some federal funding would be required, "which I think is going to make that very unlikely."

In addition, Moss said, "lower Manhattan has undergone such a resurgence, a [one-seat] link is not essential."

The Regional Plan Association said the pace of redevelopment should not lessen the need for the link.

"Before 9/11, businesses were leaving lower Manhattan because of the lack of reliable airport access," the group's spokeswoman, Wendy Pollack, said. "Now, the most reliable access from lower Manhattan is a $70 cab ride, and that's not always reliable."

She said the link would also serve the growing number of residences in lower Manhattan. "The World Trade Center area has become a very desirable residential location, and what would be better than to have direct airport access?" she said. "Five years from now, the airport link could be a hugely attractive addition to the site."

The Metropolitan Transportation Authority, not the Port Authority, had been the lead agency in exploring the Kennedy link. "We began a study but did not complete it," MTA spokesman Aaron Donovan said last week. "It became clear as the study was underway that the proposal would have offered a relatively small incremental benefit over the existing two-seat ride, at a prohibitively expensive cost."

He said the plan had been to use Long Island Rail Road or city subway tracks from lower Manhattan to the Kennedy Airport terminals, but the trains would have had to switch from manual to automatic control at Jamaica, where the AirTrain provides a link to Kennedy.

"There would not have been very much time savings, or ridership gained, over the existing two-seat ride to JFK," he said.

While the proposal highlights the benefits to the trade center, the Port Authority argued that it would also benefit New Jersey residents who do not live near the current half-dozen PATH stations in that state.

New Jersey commuters, for example, could park at Newark Liberty and take PATH to Manhattan.