If the Physics' postulation is correct and the front end dug in then the momentum would have taken the train forward and spun the cab car around and caused the following cars to follow. It seems that the hoghead must have slowed down before hitting because the force at 80 mph would have sent more cars from the track (in my opinion) due to the lighter weight of the cars.

My question is since the crew saw the truck stuck on the track how long does it take to stop a four car train that weighs approx 300 tons with 130 of that in the trailing loco. Do they have blended braking that should stop them quickly or because they are light does the train actually take longer to stop due to the limited number of brakes per ton.