To his credit, Michael Bay does try to put more human touch into "Transformers: Dark of the Moon," aiming to make up for the clattering mess of overgrown kitchen appliances that duked it out in the franchise's last installment.

Bay went to the far side of the moon and even to planet Vulcan, enlisting John F. Kennedy, Richard Nixon, Neil Armstrong, Buzz Aldrin and Mr. Spock in search of the human face of the "Transformers" universe.

And he came back with another loud, long, bruising and wearisome onslaught of giant, shape-shifting robots. The human element arises largely from archival footage involving the 1960s moon race, along with images that may disturb younger kids as a succession of screaming, scrambling humans are vaporized by the 'bots like insects in a bug zapper.

In 3-D, too, so you get to wear those clunky glasses for the franchise's longest movie yet.

It really felt like people didn't matter in 2009's "Transformers: Revenge of the Fallen," a mega-blockbuster despite being little more than a turgid assemblage of computer-generated machine parts thrashing about.

So Bay and his collaborators set out to show the flesh-and-blood consequences in the war between the benevolent Autobots and their evil counterparts, the Decepticons.

But human consequence in a Bay flick means more shots of Shia LaBeouf bellowing while he and his pals get battered around amid the mayhem. The action sequences drag on and on, and while the stunts and digital imagery are even more dazzling than the visuals of Bay's first two "Transformers" tales, it all flies by in such frenzy that it remains a challenge to figure out who's who, which robot is which, and what machines you should be rooting for.

It's a thin line between the idiotically incomprehensible "Revenge of the Fallen" and the merely incomprehensible of "Dark of the Moon."

Unlike "Revenge of the Fallen," part three actually has a plot, or at least starts with one before the movie lapses into nonsense. Returning screenwriter Ehren Kruger weaves in a 1960s prologue as NASA tracks the crash of an alien ship on the moon, prompting Kennedy to order a salvage mission under cover of his call to beat the Russians to the lunar surface (along with Kennedy, the prologue features archival footage of Nixon and moon walkers Armstrong and Aldrin, the latter also turning up in a cameo as himself in present times).

The crashed vessel carried technology that was the last hope of the Autobots in their losing battle against the Decepticons on their home world. It also carried the leader of the Autobots, Sentinel Prime (voiced by Leonard Nimoy, who also is seen briefly as Vulcan Spock from a "Star Trek" episode as Paramount Pictures forges a strange marriage of its two big sci-fi franchises).

Sentinel Prime is revived by his protégé and successor, Optimus Prime (again voiced by Peter Cullen), and the two lead their scant Autobot forces and human allies against Decepticon leader Megatron (Hugo Weaving) in the race to recover the lost technology.

Earth's fate is again in the balance, with LaBeouf's Sam Witwicky naturally at the center of things. Bay cast out Megan Fox as Sam's girlfriend, replacing her with new romantic interest Carly (Victoria's Secret model Rosie Huntington-Whitely, who makes a laughably titillating, skin-bearing entry into the movie, reminiscent of Fox's introduction in the last one).

Like Fox, Huntington-Whitely is never expected to do more than look hot while in deathly peril in the clutches of hulking robots, so in that regard at least, her big-screen debut is a success.

LaBeouf is reunited with Josh Duhamel and Tyrese Gibson as leaders of the human strike forces, along with John Turturro as a former government operative who jumps back into the battle.

Some genuine humor arises early on, courtesy of John Malkovich as Sam's quirkily autocratic new boss and Frances McDormand as a supremely capable but by-the-book intelligence chief (hearing Academy Award winner McDormand state with conviction that "it's some sort of prototype Autobot technology" is a natural giggle).

Alan Tudyk provides a few laughs as Turturro's unstable assistant, while Patrick Dempsey manages at least one chuckle as Carly's wealthy boss, a guy who talks up the need to "liaise" with the humungous robots.

As they always are, Kevin Dunn and Julie White are annoying as Sam's parents, whose roles serve no purpose this time and could have been jettisoned to save precious time.

Whatever humor the movie offered fades as Bay ratchets up the relentless action, the battles grinding on so long that the motion and noise turns numbing (the mind really can wander during all this ruckus; stare long enough at some of the Decepticons' flying machines and they oddly start to resemble jumbo shrimp).

The 3-D images, created through a combination of 3-D cameras, 2-D converted footage and digital effects, generally are crisp, avoiding the blurriness that has spoiled some 3-D tales. Fans of the format should be satisfied, but for the anti-3-D crowd, the movie probably will not win any converts; the 3-D images really don't add anything.

"Dark of the Moon" mostly is an expensive exercise in rubbernecking, the audience getting to watch colossal carnage and destruction from the safety of stadium seating.

And human consequence? Well, the most human thing about "Dark of the Moon" is the age-old, gravelly voice of Sentinel Prime, even though Nimoy unfortunately is called on to parrot one of the most-cherished lines of the "Star Trek" canon in a bad context.

It's hard to care about what happens on screen when an extra-terrestrial robot, speaking with the same voice as a pointy-eared Vulcan, provides the most human connection in a movie.

"Transformers: Dark of the Moon," a Paramount Pictures release, is rated PG-13 for intense prolonged sequences of sci-fi action violence, mayhem and destruction, and for language, some sexuality and innuendo. Running time: 154 minutes. One and a half stars out of four.