Let’s be very clear. Unstoppable was not good. It was loud, headache-inducing, teeth-rattling driving action with little plot and no character development. The acting was limited to roguish smiles and worried glances. The score was annoying and cluttered up an already cluttered soundscape and the cinematography was the caliber of World’s Wildest Car Chases. All around, Unstoppable was a pretty terrible movie.

Yet it’s imminently watchable.

If you’re dead set on making a bad movie, which director Tony Scott (The Taking of Pelham 123, Man on Fire) is pretty much always determined to do, there are certain ways to make the dreck more palatable to audiences. First, hire a likeable cast. Scott has this in the bag as he somehow keeps getting Denzel Washington to be in his awful movies (I suspect blackmail). Denzel is joined by Chris Pine (Star Trek), who is growing on me and is quite likeable as a blue collar hero-type guy. He’s scruffy and kind of dirty and looks more attractive to me than he ever has before.

The token female is very important. She has to be someone men and women will like despite whatever dumbass thing she may be doing at the time (movies like this don’t often spend time on developing real women as characters). Unstoppable lucked out on two fronts. First, they got Rosario Dawson who is always great to watch and she does “exasperated woman surrounded by dumb men” very well. Which leads to her second strong point—her character wasn’t totally dumb. She was, in fact, a strong, smart, capable woman in a figure of authority who actually knew what she was doing. It made for a much more tolerable viewing experience since I could feel good about Dawson giving instructions to Denzel.

There is no character development in Unstoppable but Denzel and Pine manage to infuse their characters with winning personalities based solely on the brightness of their smiles and the crinkliness of their eyes. In fact, we have zero reason to like Pine’s rookie railroader, “Will Colson”. He got his job courtesy his union-connected family. He’s kind of a whiny bitch about work. He tries to blame Denzel for his mistake in putting too many train cars on their freight engine. He’s under a restraining order from his wife because he’s a psycho who flipped out when she was texting her sister-in-law and he ends up pulling a gun on a cop, who happens to be a mutual and long-time friend of his wife. Really, we should hate this dude. But his eyes crinkle just so and he has a pretty smile. All is forgiven!

Denzel’s longtime veteran train engineer “Frank” is at least not a psycho. He’s a sympathetic widower with two daughters and he comes with those traits all Denzel characters have—honesty, courage, forthrightness, fairness. I’m not sure Denzel is acting here as much as he is “showing up”. Still, we don’t want anything bad to happen to “Frank” and people actually cheered when he made it at the end. It goes back to getting a likeable cast. We like Denzel, we root for Denzel, we cheer for Denzel.

After securing a likeable cast, the next thing a bad movie has to do to increase watchability is continually raise the stakes so that the audience can never disengage with what’s happening on the screen. Scott has no sense of subtlety—he wouldn’t recognize it if subtlety punched him in the nuts—but he can set up an effective action sequence. Since Unstoppable is pretty much a 90 minute action sequence, Unstoppable is oddly engaging. The stakes go something like this: There is a “coaster” train on the tracks—it isn’t going very fast. Oh wait, that “coaster” is actually under power and is in fact barreling down that tracks in excess of 70 MPH. Oh WAIT, there is a train full of (screaming) children in the runaway train’s path! OH WAIT the train is headed for a large city full of fuel depots, and OH WAIT the conductor’s attractive family lives right on the train tracks!

Increasing tension is a surefire way to keep the audience engaged even in a bad movie. As the stakes for the runaway train increase, so do the methods of keeping the audience stressed out and worried. The score is a constant buzzing under the dialogue about how fast the train is going and the action is punctuated with loud pops and cymbal crashes, assuring that no one can nap through this movie. In moments that would be better served by silence there was inevitably a crescendo. The sound effects, too, contribute to the cacophony, especially the animalistic roar of the runaway train’s engine as it zooms by. The entire movie was calibrated to keep the audience in a perpetual state of anxiety, worried that at any moment one of those school children will be vaporized.

Unstoppable is really not good. It’s not worth your $12. It might be worth a rainy afternoon on the couch when it’s on cable. But it is amazing how many people walked out of that theater smiling and fist-pumping, acting like they themselves saved that train full of school children.