NEW YORK -- A $10 billion replacement for the Port Authority Bus Terminal in Manhattan is a "piecemeal" solution to the region's trans-Hudson commuting crunch, and should be scrapped in favor of building a second bus terminal in the basement of the Javets Convention Center a few blocks away, a regional planning group recommends.

The region's highest priority, the planning group said, should be the proposed Gateway rail tunnel project.

The Manhattan-based Regional Plan Association says building an additional terminal beneath the Javits Center on 10th Avenue, along with upgrades to the existing bus terminal, would be cheaper and have far less impact on the surrounding Midtown neighborhood than the current proposal to replace the 67-year-old overcrowded bus depot on 8th Avenue.

A replacement bus terminal was included in a 10-year, $32 billion capital plan adopted by the Port Authority in February, though only $3.5 billion was earmarked for it. In April, the Port Authority said it would weigh upgrading the terminal rather than replacing it.

The Regional Plan Association, or RPA, made its recommendation in a report released Wednesday titled, "Crossing the Hudson: How to Increase Transit Capacity and Improve Commutes."

"A new facility in the basement of the Javits Convention Center would have many advantages over other proposals," the report states. "It can be built very quickly -- an important consideration since both Penn Station and the existing bus terminal are at risk of failing. It would be much less expensive than building a new bus terminal. It does not require the demolition of the existing PABT, but would complement it with better service to the Hudson Yards and other destinations that would reduce the demand on the PABT, which would be renovated to extend its useful life another 20 to 30 years."

In a teleconference with reporters on Wednesday, RPA President Tom Wright said a Javits terminal would relieve the existing Port Authority Bus Terminal of 20 to 30 percent of its current ridership. He did not have an estimate for the cost of a Javits terminal or necessary upgrades to extend the life of the existing bus depot.

The recommendation drew criticism from supporters of replacing the old bus terminal, including state Sen. Loretta Weinberg, the Senate majority leader, and Sen. Bob Gordon, both Democrats from Bergen County, who issued a joint statement blasting the bus terminal recommendation as, "flawed, premature, unrealistic and New York-centric."

"The Port Authority is currently assessing the viability of 'building up' on the current Port Authority Bus Terminal site - an option that we support," the lawmakers stated. "Unlike other proposals to build a new bus terminal a block to the west, this option would continue to provide commuters with easy access to all of the Eighth Avenue subway lines and would not require the acquisition or condemnation of any additional property in Manhattan's Hell's Kitchen neighborhood."

Tabling a new Port Authority Bus Terminal was among several RPA recommendations for dealing with the region's increasingly pressing shortage of trans-Hudson capacity, made all the more critical by the deterioration of the aging Hudson River rail tunnels, whose problems have led to the so-called Summer of Hell service disruptions.

Most important, the RPA says, is the immediate start of construction on the Gateway rail tunnel project, intended to double trans-Hudson rail capacity and reduce delays on NJ Transit and Amtrak trains.

Wright told reporters the Gateway project should be extended east, under Manhattan, to create rail access to the LIRR's Sunnyside Yards in Queens. Write said the expansion would further increase trans-Hudson capacity by another 40%, while allowing New Jersey commuters to travel directly to jobs in Queens or on Long Island, while giving Long Island and Queens commuters one-seat access to New Jersey jobs.

He acknowledged this would require cooperation between NJ Transit and the Long Island Railroad -- and place New Jerseyans on LIRR Trains and vice versa. But that would be an operational hurtle only, he said, adding that some kind of regional payment system usable on various rail systems could be deployed.

Wright said the expansion could add another $7 billion to the cost of the Gateway project, but he was was hopeful the federal government would honor its commitment to cover half of project's price tag, now roughly projected at $24 billion, including replacing a pair of century old tunnels and related work.

"Rail trips in and out of Penn Station have nearly tripled in the last 25 years, bus trips have grown by 83%, and PATH ridership is up by 27%," the report states. "RPA's research projects that this trend will continue over the next two decades, requiring far more capacity than the existing facilities can provide."

Steve Strunsky may be reached at sstrunsky@njadvancemedia.com. Follow him on Twitter @SteveStrunsky. Find NJ.com on Facebook.