contact with the train could well have been avoided if the chap had been stood behind the yellow, like everybody else in the video, until the train had come to a complete stop.
And that ladies and gentlemen, is why you stay behind the yellow line "until the train has come to a complete stop."
The person in the video stumbled inexplicably, put out his hands to stop the fall, and hit the train. If he had been behind the yellow line, I'd say it was 50-50 whether he would have been able to completely stop himself from falling by taking a step or two forwards, or if he would have just fallen over completely and still hit the train as he fell.
The only way you can completely stop falling people from hitting the train is to move the yellow line to be at least 2 metres away from the platform edge. It's never been entirely clear to me how the position of the yellow line is chosen. Yes the line
lowers the risk of somebody falling and hitting a train, but it clearly won't stop people from hitting the train in every case where they fall over completely, faint, etc. Therefore we must have.decided that some kinds of stumbles and falls are an acceptable risk, but not all.
Why is the yellow line a different distance from the edge of the platform at different stations? At some tube stations it is laughably close to the platform edge. Maybe the person in the video normally travels between two such stations and is therefore standing in a "normal" position for their regular stations?