(USA) Can a film about a runaway train with a dangerous cargo avoid the triteness trap? Not a chance, if this example is anything to go by. Old timer and locomotive engineer Frank Barnes (Denzel Washington) and young upstart conductor Will Colson (Chris Pine) are on a routine job when they get word that the unmanned, airbrake-less, half-mile-long train 777 is headed their way. After several failed attempts by the railroad company to stop the train, it’s up to Barnes and Colson to save the town of Stanton from annihilation at the hands of 777 and its cargo of molten phenol.It is admirable how “Unstoppable” manages to use almost every train/pursuit/disaster cliché, stopping short of having a hero’s life threatened by a tunnel. A mismatched pair of main characters; check. A veteran close to retirement who places photos of his daughters on the console; check. Children in danger; check. Loved ones on the sidelines watching the events unfold on TV while whispering “Come on”; check. Completely over-the-top news commentary; check.That aside, “Unstoppable” simply has no idea what it is. To be fair, there are some genuinely hair-raising moments in the first part of the film, as tight framing, a shaky camera, irregular zoom-ins and gratuitous train undercarriage shots keep you on edge. Halfway through, though, “Unstoppable” becomes downright comical, with the seriousness of the situation thrown out in favor of typical action movie banter between Barnes and Colson. To finish off, it descends into a reboot of the concluding sequence from Bill & Ted’s Bogus Journey featuring groups of people cheering, fist-pumping and shaking hands. Sadly, without a time-traveling phone booth and “God Gave Rock ‘n’ Roll to You II” by KISS playing in the background, it’s unbearable.The one positive of “Unstoppable” is that there is no arbitrary villain or enemy behind 777. No terrorists or disgruntled employees gone postal here; just the incompetence of a railroad worker played by the obese sidekick from the TV series “My Name is Earl.” With many paper-thin characters, an unsurprising scene with Denzel running on top of a train and a “what happened to them after the film” montage before the end credits, “Unstoppable” is funnier than most intended comedies.