That shouldn't be a problem, even if they were off to the side, because that would be where 18 wheelers of the same weight would pass in line regularly.
"Looking at the videos its just a bit strange how it fell, more like a controlled demolition. I would ask some of those demolition experts if it could be done without using explosives.
One of the truss members, or connection, around the SE pier failed. That caused the roadbed to tilt down, drop, pop at all the bearing points, and drop straight down. The rest of the road bed followed as a rigid sheet (road bed + superstructure, straight down). I can't find the SE king post in the rubble. The SW one tiddly winked out and off it's pile intact. You could ID different truss members, or supports on the SE side which are critical. What's important though was for someone to do that before this happened and recognize that something was wrong in that area. The steel there was already failing and had strained to a point, that the bearings in the expansion joint were taking up unnatural stress. That's why a normal load triggered a catastrophe.
As far as a man made "crack" goes, the investigators that have the broken pieces in hand and can see how it all fell, could spot that right away. They probably already know why the bridge fell. They won't release that until they reconstruct the whole thing on paper, instead of envelopes and go over it a few times.
Once the king post buckled a little, that expansion joint above would tear loose, popping pins across the joint, from SE to SE very fast. That would result in the fall seen in the video and reported as "the center falling, or dropping out". So the fatigue was in the bottom chord, or the elements of the chord attachment at the SE pad.
Here's the before for ref.
