Yeah, I saw that, but the bridge's safety warnings had been broken for two days. Why did they not simply shut the lift down until they were fixed? Lame.
My guess is that to shut the lift down would have required that they close the roadway completely and leave the bridge in the "up" position, because ships and boats would have the right of way in such a scenario. Since it is a heavily-traveled roadway, they probably did not think that would be practicable. However, it certainly looks like negligence was involved...