As the video states this was flagged by inspections 14 times over 7 years or so.
There's even inspection reports of one of the cross supports rusted through and disconnected, a cable taking some of the strain. At the very least the bridge should have just been closed, as unsafe.
Warning in this context means something obvious to the unsuspecting user that collapse is imminent. Like a building creaking or buckling minutes or hours before finally giving way.
In engineering terms thats a mode of collapse, thing, not about people actually warning.
When we do design, we're generally designing things so that if it fails it does so in a way that doesn't suddenly all collapse at once, but first deforms for a while so people can get away.
There's even inspection reports of one of the cross supports rusted through and disconnected, a cable taking some of the strain. At the very least the bridge should have just been closed, as unsafe.