That timeline implies that there was only four minutes to respond. Is that correct? Where was the ship going? Does it travel under this bridge on its own power rather than a tug boat?

What I am wondering is: why couldn't the bridge have been blocked off preventing casualties? It seems like more than just the boat and operators' failing if there's no time or secondary precautions if such failures occur.

I wonder if it makes sense to protect bridges with pylons like they have in front of buildings to stop cars and trucks.