Logical Move By Depressed Man
Why his life was in danger?
Since the man was firm on his decision of ending his life he started to walk on a railway bridge. By doing that, he made sure no body would save him & even if he falls in river, the death is sure as he didn't know swimming. After crossing the bridge more than half way, he changed his mind. Now by running back wouldn't be feasible option as train was speeding towards him at greater speed. Only way to save life was cross the bridge before train hits him.
Hence he ran 10 feet towards the train & jumped off the track thereby to save his life.