The last time action director Tony Scott focused on rail transportation, the result was the botched subway thriller "The Taking of Pelham 123." In "Unstoppable," he's back on the right track and running at full throttle. This is a terrific, sweaty, men-on-a-mission adventure, with heroic blue-collar railwaymen, pencil-pushing bureaucrats and hotheads in the head office battling to halt an unmanned runaway train.

It's based on an actual event: in 2001 a 47-car CSX train with a cargo of toxic chemicals -- but no engineer in the locomotive -- careened across three counties in Ohio before it was brought under control.

"Unstoppable" ups the ante with spectacular car wrecks, a derailment and helicopter stunts, yet it's filmed with a great sense of authenticity. Scott's film is a superb blend of crowd-pleasing hokum and tense realism. The vibrations and noise and chaos of the collisions are the real McCoy. Scott mostly avoided computer-generated effects in favor of shooting real vehicular carnage. It's crash-tastic.

Screenwriter Mark Bomback paces the tale well, establishing the setting and characters vividly before increasing the momentum. The movie starts small, with an engineer jumping out of his cab to throw a switch as Engine 777 coasts through the rail yard. When he stumbles trying to re-enter the locomotive, his fellow engineers have a horse laugh. It's embarrassing for the hapless driver, but the train's safety devices will kick in and bring 777 to a halt. Only they don't.

Through a perfect alignment of human and mechanical failures, the train jogs across northern Pennsylvania, then races, then rockets. When a fathead executive pooh-poohs the seriousness of the situation, dispatcher Rosario Dawson bellows, "It's not a train; it's a missile the size of the Chrysler Building!" Like last summer's "Unleash the Kraken," this is a movie quote destined for immortality as a singles bar pickup line.

Apart from a couple of shameless sequences using a trainload full of schoolchildren and a horse trailer stuck on the tracks to generate cheap suspense, "Unstoppable" is a solid, believable story.

The plot's few stumbles are balanced by the scope and skill of the whole thing. Denzel Washington and Chris Pine are solid as ticked-off railroad men. Washington is being pushed into early retirement so that younger, cheaper conductors like the inexperienced Pine can take over. They don't much like each other, but when their milk run puts them near the cannonballing 777, they ride off to face destiny.

The actors are fantastic at creating empathy for what could have been a couple of stock working stiffs. As usual, Washington is Mr. Composure, cool in the face of impending catastrophe. What the hell, his girls are grown, his wife is gone and now his career is over. His eerie got-nothing-to-lose calm freaks out greenhorn Pine, who was sort of hoping to live long enough to reconcile with his own estranged wife. The two do a bit of manly bonding as they put themselves in harm's way. Hashing out their personal subplots doesn't give the story scope; it's the weakest element of a taut yarn.

The film can't stay lost in the weeds for long, though; there's a zillion gallons of chemical doom hurtling toward Dead Man's Curve on sparking, squealing steel wheels. Pine and Washington both get big hero moments filmed with kinesthetic impact; when they braced to leap between boxcars I felt the tendons in my legs tighten.

Along with the drama and visual excitement, there's an undercurrent of working-class resentment percolating through the film. The villain of the tale is the train, a destructive, unfeeling beast that becomes as much a character as the shark in "Jaws." But the secondary bad guy is the incompetent executive overseeing the crisis. He sees the emergency more as a matter of potential stock devaluation than a disaster in the making. Next to halting the train, we want to see him get his comeuppance, and Scott delivers.

The real heroes here are the bullheaded grunts who appear as liabilities on his balance sheet. They're unstoppable.

Colin Covert • 612-673-7186