[S.T.D.]

I distinctly recall watching a docu on this in "seconds from disaster" a while back. IIRC a week or so before, the driver got late by about 17 minutes by the end of his run (note that Japanese railways are supposed to be like clockwork. 1 minute off means the some of the passengers will miss their transfer to the other trains). He got punished with a whole lot of verbal abuse, think drill sergeant-breathing-down-your-neck-24-7. It was kind of hellish o go through and left him with emotional scars.

Fast forward to the day of incident he was trying hard to improve his times and made a small mistake, tripping a speed-limiter. This caused him to be late by around 30 seconds on his next stop. Trying hard to make up for it he speeds up, only to have it backfire by overshooting the next station by something like 10 meters so he has to back up, costing him around 5 minutes. His fear of punishment drives him up the wall, and he decides to floor it going about twice the max speed for the curve resulting in the crash.