Terminator 3: Rise of the Machines is the roller-coaster ride we’ve come to expect from the franchise, all right, but this time it’s the rickety, wooden variety.

From a visual perspective, the film’s rapid-fire approach is outstanding. Relentless and raw, the stellar action sequences are among the best of the summer. And at a by-today’s-standards lean 109 minutes, it doesn’t overstay its welcome.

But the film sadly shortchanges the saga’s characters and their intriguing relationships so vividly brought to life 12 years ago with Terminator 2: Judgment Day. The quieter, surprisingly moving directions that segment took are nowhere to be found, leaving us visually stunned but curiously uninvolved. (James Cameron, the series’ co-creator, is not involved with this installment.)

Set about 10 years after the events of T2, the third chapter opens on John Connor (Nick Stahl), foretold to become humanity’s savior in a future war against machines, but now a homeless vagabond. In T2, John, his now-dead mother Sarah and the T-800 (Arnold Schwarzenegger) changed the timeline of events that led to a nuclear holocaust brought on by artificial intelligence. 

Feeling he’ll no longer have to become a leader, John is still cautious, living life “off the grid,” with no address, no phone and no electronic ties. But he learns his actions a decade ago merely postponed, not stopped, the attack.

Guarded yet again by a T-101 sent back to protect him, John must ward off the deadly T-X (Kristanna Loken), a female Terminator who, among other powers, can control other machines. Along for the mission is Kate Brewster (Claire Danes), a veterinarian with past ties to John.

Director Jonathan Mostow brings to Terminator 3 the same wily intensity he gave Breakdown, his exceptional breakthrough film. His expertise with road chases is best showcased in an early scene involving ambulances, cop cars, fire trucks, and one supremely destructive crane.

Plus, it’s got some laugh-out-loud touches of sly humor that have carried over. The T-X employs obvious advantages of being an android covered by sexy female skin. How Schwarzenegger, now reincarnated as the T-101, gets his clothes is a cheap, but good, laugh. And one of the very expensive-looking explosions is essentially a very funny punch line.

The acting is fine across the board. She’s no substitute for Linda Hamilton, but Danes at least casts off her typically whiny persona to create a reasonably strong female character. Loken is a mostly silent, but potent menace (the rush she gets licking John’s blood is creepy). And Arnold, well, he doesn’t seem as into it as before, but it is his signature role and he’s still perfect for it.

But there’s no consistency in the characters or, for that matter, the story. The most interesting and touching element of the series — the T-101 as John’s father figure — is intriguingly introduced, but quickly junked. By darting his eyes and cracking his speech, Stahl hints at how totally alone John is in the world, but it doesn’t connect the way it should.

And even given the franchise’s constant talk of fate and destiny, the plot points here hinge on some exceptionally ludicrous circumstances. It’s hard to think the world’s fate had anything to do with a junior-high make-out session in someone’s basement circa 1991. Maybe the writers have a soft spot for Queensryche and Mr. Big.

The faults of Terminator 3 can be overlooked up to its overblown finale, a bleak bender that raises many more unsatisfying questions than it gives satisfying answers. It feels less like a resolution than a loophole should Schwarzenegger not become California’s governor and need a day job again.

What was impressive about the first two Terminator films, particularly the second, was that they were B-movie stories with A-movie heart, themes and characters. A skillful but spiritless thrill machine, Terminator 3 makes a good case for why Cameron and company perhaps didn’t envision a trilogy.