New York ? After four years of planning and squabbling over the future of Ground Zero, 2006 will finally be “the year of the hardhat” at the hallowed site.

“It’s going to be a year when people are actually going to start seeing activity,” Port Authority Executive Director Kenneth Ringler said during a walk-through of the site.

“By the end of 2006, we estimate there will be 1,000 construction workers here,” he said.

Five hundred will work on the PATH station, which is being transformed into the Grand Central Terminal of downtown.

The other workers will focus on projects designed to rebuild what’s mainly a giant hole in the ground – one that draws hundreds of tourists a day along Church and Liberty streets.

The PA, which owns the 16 acres, estimates contractors at the World Trade Center site will pour 50,000 cubic yards of concrete this year and construction will total $230 million.

Some concrete will go into fittings for the World Trade Center Memorial, starting in March, even with a number of 9-11 family groups criticizing the design.

Developer Larry Silverstein, whose long-term plans are being challenged by the PA, moved closer last week to a spring start on his 1,776-foot Freedom Tower, set for the northwest corner.

He awarded a contract to Petrocelli Electric, which will clear space for the foundation by relocating high-voltage lines and other wires serving PATH.

Another first-quarter project will be the temporary underpinning of the box that encloses the No. 1 subway line, which runs through the WTC site and separates its western portion from the not-yet-excavated east side.

Excavation of the east side – bordered by Church Street – will begin at the end of the year.

“We have to dig that area out, down to the lowest elevation, so we can put in parking and other structures,” including multiple levels of stores the Port Authority wants to develop, Ringler said.

The surge of activity in 2006 is but a warm-up for years of expanding construction at Ground Zero and the surrounding area.

Goldman Sachs recently started to build its 43-story headquarters diagonally across West Street from Ground Zero, and construction of the MTA’s Fulton Street Transit Center has led to the excavation of Dey Street.

The Lower Manhattan Construction Command Center, formed by Gov. George Pataki and Mayor Michael Bloomberg, estimates 10,000 to 15,000 construction workers a day will be employed downtown when projects are in high gear over the next three to five years.

Lowermanhattan.info will become the new Web site of the command center, offering updates on construction and showing what the finished projects will look like.