NEW YORK (Bloomberg) — Tony Scott loves runaway trains.

After directing the remake of "The Taking of Pelham 1 2 3," the British action junkie returns to the rails with "Unstoppable", a thriller about an unmanned freight train hurtling through the Pennsylvania countryside with a potentially disastrous load of toxic chemicals.

Veteran engineer Frank Barnes (Denzel Washington) and rookie conductor Will Colson (Chris Pine) are on a train headed straight toward the out-of-control locomotive, which took off by itself when the driver hopped out of his cab to change the track switch and accidentally left the engine in full throttle.

Barnes and Colson make a heroic attempt to save the day, but the real stars are the trains, which get more screen time than either of them.

The red-and-yellow, half-mile long train with the doomsday cargo is ominously described as a "missile the size of the Chrysler Building." The blue-and-yellow locomotive in its path is older, smaller and slower. On paper, it looks like the worst mismatch since Tyson-Spinks.

Scott mixes overhead shots of the trains with close-ups of the actors, using quick cuts to heighten the tension. He also eschews computer effects in favour of real stunts, like running on top of moving rail cars, jumping from a truck onto a speeding train and dangling from a helicopter.

It makes the film, based on a 2001 incident in Ohio, scarier than the blockbusters created by tech geniuses sitting in front of a computer screen. (I could have done without the silly subplot about a group of schoolchildren taking a field trip to learn about train safety.)

Though Washington and Pine don't have much to say, screenwriter Mark Bomback gives them enough angst to foster sympathy. Barnes is a widower estranged from his two teenage daughters and about to lose his job. Colson is separated from his wife and son and resented by his new colleagues because he got his job through family connections.

Their corporate bosses want to derail the runaway train before it reaches a mid-size city with a winding track that almost guarantees a lethal crash. Instead, they attempt a risky manoeuvre that involves running their train in reverse until it gets close enough to link with the runaway, then pulling in the opposite direction to slow it down.

With help from a calm yardmaster (Rosario Dawson), a nerdy safety inspector (Kevin Corrigan) and an audacious welder (Lew Temple), Barnes and Colson proceed with their tug-of-war plan. Get onboard if you love to be terrified.

"Unstoppable" is showing at the Liberty Theatre