WORD that the Port Authority has volunteered its services as construction manager for the 9/11 memorial is the worst news yet out of Ground Zero—but not because it means the PA is trying to muscle out the memorial foundation.

The real problem is the scary prospect that "Reflecting Absence" will actually be built as now conceived, in all its earth-hogging, morbid mediocrity.

The memorial scheme calls for a subterranean crypt and museum beneath waterfall-drenched Twin Tower footprints. Under-focused and over-engineered, it promises a result between mere disappointment and outright disaster.

It's considered impolite to criticize this design—first dreamed up by architect Michael Arad, then nudged along by Vietnam Memorial designer Maya Lin, later massaged by landscape architect Peter Walker and architectural firm Davis Brody Bond, and tweaked on an ongoing weekly basis by a horde of bureaucrats.

But as a few family-victim activists file suits aimed at seizing even more of Ground Zero's precious square footage for their own purposes, it's time to say enough—and maybe recapture some land already allocated for the memorial and put it to better use.

TO say that "Reflecting Absence" absolutely stinks is blasphemous. It's regarded as both disrespectful of 9/11's victims and their survivors and a threat to bogged-down fund-raising efforts.

But stink it does. (And that's the real reason fund-raising has lagged embarrassingly.)

Too big and too complex, the mostly subterranean project is more likely to induce claustrophobia than catharsis. Why must we venture through an underground labyrinth to mourn victims of an atrocity that took place high above ground and in broad daylight?

The memorial foundation crows that it has pledges for $100 million of the needed $500 million, a figure certain to mushroom. In fact, $100 million is peanuts—especially since half of it came from one nonprofit foundation and two Downtown-based companies (Bank of N.Y. and Deutsche Bank) that would surely be glad to see anything fill the empty pit that Ground Zero has been since the cleanup ended in 2002.

The foundation blames everything but the product itself. Before, it was the dispute over the since-booted Freedom Center. Now, they're squawking that donors will construe it as a "government project" if the PA sends in its engineers.

Sorry—but those cowed by a handful of noisy zealots are pretending not to see the Emperor's New Clothes. The obvious truth is, citizens by the millions have not fallen in love with "Reflecting Absence."

THE first error was to mistake size for substance. The memorial quadrant consumes seven of Ground Zero's 16 acres—an extravagant commitment to justify Gov. Pataki's calling it the "centerpiece" of the WTC site, and an exercise in gigantism as arrogant as the Twin Towers themselves were.

You can't grasp how big the memorial is from street level; for that you need to gaze down from a high floor of the new 7 World Trade Center, as I did last week.

By far the site's largest identifiable feature is the pair of tower footprints, each one acre. Yet they take up only a small fraction of the memorial ground, which is to be bounded by West and Liberty streets and newly extended Greenwich and Fulton streets.

You perceive, too, how little room this leaves for everything else: The Freedom Tower, three more office buildings, PATH station, cultural buildings and shopping mall—plus those new streets—are all tightly shoehorned into a narrow L around the memorial.

But shouldn't the memorial be enormously scaled, to reflect the full horror and toll of 9/11?

Of course, it need not be. The dead of 9/11 numbered under 3,000. The Vietnam War cost the lives of 58,000 Americans—yet Maya Lin's memorial in Washington, D.C., commemorates them eloquently and unforgettably in a wall a mere 493 feet long and 10 feet high.

Isn't there a difference, though, between memorializing soldiers who perished years earlier in a distant war and memorializing civilians murdered much more recently in New York? Doesn't the greater immediacy of 9/11 justify thinking big?

Maybe—but comparisons to the Washington project are unavoidable. It was Lin herself, as one of the LMDC's judges, who pushed for Arad's design. Fans of "Reflecting Absence" have exploited that fact, noting that Lin, like Arad, was largely unknown when her Vietnam design was chosen and that it first struck many as cold and abstract—implying by the supposed parallel that the Ground Zero project will prove every bit as successful.

IF Arad's plan looks cold, though, it's far from abstract: If anything, it's literal to the point of maudlin, depicting the Twin Tower footprints as resting places for the lost souls of 9/11.

Yet none of its numerous, expensively engineered and ultimately sterile components is likely to elicit the involuntary outpouring of emotion that overcomes visitors to the Vietnam Memorial. For this, we can thank Daniel Libeskind's master site plan, which earmarked the vast southwest quadrant for the memorial, plus Pataki's insistence that the footprints not be built upon.

Competition to fill so much space while leaving the footprints intact yielded a "winner" without a focus. Thus "Reflecting Absence" is full of elements that variously 1) likely can't be built as envisioned; 2) resemble an underground Las Vegas; or 3) will work (or not) depending on details beyond anyone's power to predict.

Start with focus: What, exactly, in all this sprawl, is the "memorial"? Is it the pools with water cascading (for no good reason) into smaller, square pools-within-the-pools? Or is it the meandering ramps visitors will navigate into the subterranean voids?

Is to be the underground vault's maze of corridors that look, in LMDC renderings, like an airport concourse? Or the memorial museum, dominated by a 240-foot-long chamber and full of pictures, artifacts and "contemplation" rooms? Where the Vietnam wall tugs at your heart, the only pain a Ground Zero visitor will likely know is sore feet.

ALTHOUGH it pretends to shun sentimentality, tomb- like "Reflecting Absence" embraces the comforting perception that victims' ashes lie in the earth beneath the footprints. But, although horrible to face, their molecular remains were also dispersed far and wide in the smoky holocaust.

Even if the remains had, as Arad's design implies, settled neatly into chambers beneath the towers, so literal a narrative of their fate deserves a better context than the gimmickry that will surround it.

How, for example, will the gigantic outdoor waterfalls work in winter? Will their splash and spray speak to us in some profound way, or will they look and sound more like the schlock found in suburban office parks?

Visitors underground will view the falls through windows like those in the walrus tank at the Coney Island aquarium. Precisely what historical or emotional need such a perspective serves is known only to the designers. And Walker's grove of oak trees around the pools seems only a feeble gesture to soften Arad's bleak original design, which set the pools in a barren plaza.

MAYA Lin's Vietnam Memo rial moves us to tears while containing, in a comprehensible space and form, the tragedy of a war that had no clear-cut beginning or end. "Reflecting Absence" does the opposite: A nightmare that unfolded in 90 agonizingly familiar minutes is diluted to the point of tedium—a theme park that forgot its theme.

E-mail: scuozzo@nypost.com