Order of business #1: spoiler alert the size of the Chrysler Building.
Order of business #2: complete plot summary of Unstoppable.
Denzel Washington, see, he's been railroadin' for 28 years. He is the best and most railroady railroader the Pennsylvania railroad has ever seen, and now he's just three weeks from retirement, which means that nothing could possibly go wrong. New Captain Kirk, he's a rookie who's down on his luck and currently estranged from his wife's vagina.
"Sorry to break up charm school," but it's time to get some railroadin' done! While Denzel and New Captain Kirk are discussing the finer points of The Real World: Pennsylvania Coal Country ("We're out here in the real world—this ain't training. In training, they just give you an F. Out here, you get killed"), Ethan Suplee and a ghost are busy fucking up the railroad big-time.
Ethan Suplee, one of a pair of numbnuts who are always screwing up ("You two numbnuts are always screwing up!"), is just supposed to be moving a train engine ("Number 777, otherwise known as triple-seven") from one place to another place, but after he puts it on autopilot and hops out, an invisible ghost magically pushes the lever to "THROTTLE." Then the train runs away, and since Ethan Suplee is too fat to run as fast as a train, the train becomes UNSTOPPABLE.
Okay. Next. The train is full of evil chemicals and headed for some urban areas where everyone (including orphans!) will surely die. The pair of numbnuts attempts to drive a truck alongside 777-otherwise-known-as-triple-seven and leap into its engine compartment, but they fuck it up, which means that this method of train stoppage will clearly never work. (NOTE TO EVERYONE EVER: "BECAUSE ETHAN SUPLEE DID IT WRONG THE FIRST TIME" IS NEVER A VALID REASON TO ABANDON A PLAN.)
Instead, everyone just runs around screaming for an hour, except for the railroad fat cats who are too busy playing golf to worry about dead orphans (except "What about the resulting stock devaluation?"). Then a concerned child with a subpar understanding of how train tracks work makes a great point: "It could be coming to our town next, and the high school's right next to the train tracks!" When I said "great," I was being sarcastic.
Then Denzel and New Captain Kirk drive another smaller train up next to the evil train and try pulling on it to make it stop. That doesn't work. New Captain Kirk injures his foot. Then another minor character who you didn't even remember existed (his name is "Ned") drives up alongside 777 in a truck, and New Captain Kirk jumps from the truck into the engine compartment JUST LIKE ETHAN SUPLEE TRIED TO DO TWO FUCKING HOURS EARLIER. Then he stops the train. The state of Pennsylvania is so grateful that they award New Captain Kirk a new foot and access to his wife's vagina. The end. Sorry you wasted your life.